SWALLOWING
Table 7-10 C O M M O N S W A L L O W I N G P R O B L E M S A N D M U S C L E I N V O L V E M E N T
Problem Possible Anatomical Cause
Drooling
Pocketing in the lateral sulci Weakness of orbicularis oris
Decreased ability to break down food mechanically
during the oral preparatory phase Weakness of the buccinator and intrinsic and
Decreased ability to form bolus extrinsic tongue muscles
Decreased ability to maintain bolus in the oral Weakness of the muscles of mastication
cavity during the oral preparatory phase
Nasal regurgitation Weakness of the intrinsic and extrinsic tongue
Posterior pharyngeal wall residual after the swallow muscles
Coughing or choking before the swallow Weakness of the buccinator
Coughing or choking during the swallow Weakness of the palatoglossus or styloglossus, or
both
Coughing or choking after the swallow
Weakness of the palatopharyngeus, levator veli
palatini, or tensor veli palatini, individually or combined
Weakness of the pharyngeal constrictor muscles
Food may spill into an unprotected airway
secondary to:
1. Weakness of the intrinsic or extrinsic tongue
muscles resulting in decreased ability to form
a bolus (lack of bolus formation may result in
spillage of the oral contents without initiation of
a swallow)
2, Weakness of the palatoglossus and styloglossus
resulting in decreased ability to maintain the
bolus in the oral cavity before initiation of a
swallow
Weakness of the muscles responsible for closing the
true vocal folds, false vocal folds, and aryepiglottic
folds
Decreased strength of the genioglossus resulting in
decreased tongue retraction with vallecular
residual, which spills after the swallow into an
unprotected airway
Pharyngeal constrictor weakness with residual
spillage from the pharyngeal walls after the swallow
into an unprotected airway
Decreased cricopharyngeal opening with overflow
from the piriform sinus after the swallow into an
unprotected airway
3 3 8 Chapter 7 / Assessment of Muscles Innervated by Cranial Nerves
PRELIMINARY PROCEDURES TO DETERMINE CLINICALLY
THE SAFETY OF INGESTION OF FOOD OR LIQUIDS
Test Sequence 1 1. If the patient is cognitively clear, offer a glass or cup
containing a tiny amount of water and allow the
Laryngeal Elevation: Examiner lightly grasps the patient to sip. The test is successful if the water can
larynx between the thumb and index finger on the be swallowed with one attempt, the swallow is
anterior surface of the throat. Ask the patient to inaudible, and the water is swallowed without any
swallow. Ascertain if there is laryngeal elevation and choking or coughing. If successful, proceed to Test
its extent (see Figure 7 - 7 7 ) . Sequence 3.
Criteria for Grading 2. If the patient cannot sip from a cup, offer a straw
and ask the patient to suck a small amount. T h e
F: Larynx elevates at least 20 mm. Motion is quick shorter and wider the straw, the easier the task. If
and controlled. the swallowing attempt is successful as described in
step 1, proceed to Test Sequence 3.
WF: Laryngeal excursion may be normal or slight-
ly limited. The motion may be sluggish or appear 3. If the patient cannot sip or suck, trap water in a
irregular. straw and place the straw in the side of the pa-
tient's mouth between the cheek and lower teeth.
NF: Elevation is perceptible but significantly less than Tell the patient you are going to release the water
normal. and request a swallow. If successful, proceed to
Test Sequence 3.
0: No laryngeal elevation occurs.
4. If the patient is not cognitively clear, control the
Implications of Grade: If the patient is graded F amount of water available. This is most readily done
(Functional) or WF (Weak functional), proceed with by trapping water in a straw to give to the patient.
the swallowing assessment. If the patient is graded
NF (Nonfunctional) or 0 and does not have a tra- 5. For the patient who cannot handle fluid, try
cheostomy, discontinue the swallowing assessment. thickening the water with gelatin to a consistency of
For patients with a tracheostomy, add a blue veg- thin gruel or thick pea soup.
etable dye to the bolus to facilitate identification of
any aspirated bolus during suctioning. Outcomes: If any of these trials are successful, pro-
ceed cautiously to a trial of pureed food. If none of
Test Sequence 2 these tests are successful and the patient does not
have a tracheostomy, DO N O T give the patient food
Initial Ingestion of Water by mouth until further testing (e.g., fluoroscopy) can
be conducted.
Prerequisites: T h e patient has a grade of F or WF on
Test Sequence 1. If the procedures with water are not successful
and the patient has a tracheostomy (through which
There also must be at least a grade of WF or aspirated food can be suctioned), proceed cautiously
higher on the tests for posterior elevation of the to the use of pureed food, which usually is easier to
tongue (see pages 332 and 3 3 3 ) and constriction of swallow than water.
the posterior pharyngeal wall (see page 3 3 1 ) .
Test Sequence 3
Procedure: T h e r e are several ways to get water into
the mouth to test swallowing. It does not matter Pureed Food
which is used.
The most palatable commercial pureed foods are the
The first trial of swallowing begins with a small pureed baby food fruits. The pureed meats and veg-
amount (1 to 3 mL) of water. The rationale is that etables are totally unseasoned, which is unfamiliar
should the patient not be able to swallow the water and usually unpalatable to adults. Avoid milk prod-
correctly and it is aspirated, the lungs can absorb this ucts initially because they thicken the saliva. Ask
small quantity without penalty. There also is increas- about patient food preferences and try to use
ing evidence that differences in the pH of water can something enjoyable.
cause damage to the lungs, so the small amount of
water is very important. Each procedure should be A suctioning machine is essential if the patient has
repeated at least three or four times. a tracheostomy. It is recommended that the food be
colored with vegetable dye (blue is readily seen and
is not confused with body secretions or fluids) so
that any aspiration can be readily detected as the
color appears in tracheostomy secretions.
Chapter 7 / Assessment of Muscles Innervated by Cranial Nerves 3 3 9
PRELIMINARY PROCEDURES TO DETERMINE CLINICALLY
THE SAFETY OF INGESTION OF FOOD OR LIQUIDS
Criteria for Initiating Trials with Pureed Foods gurgling indicates that food is in the airway and ask
the patient to swallow again.
1. Laryngeal elevation is Functional (F) or Weak Repeat this procedure a number of times and
functional (WF). check each response.
After four or five trials with pureed food, pause
2. Posterior pharyngeal wall constriction is at least W F . for about 10 minutes to ascertain that the patient
3. Patient has been successful in handling water in Test does not have delayed coughing because of food col-
lecting in the pharynx, larynx, or trachea. A blue aspi-
Sequence 2 or by observation. rate from the tracheostomy tube may occur sometime
4. Patient must have a functional cough (voluntary or after the actual ingestion of food.
reflex) or a tracheostomy. Some patients have a Outcomes: If the patient has no immediate or delayed
depressed gag reflex, but cough is the essential coughing, choking, or positive aspirate after swallow-
component in swallowing. The examiner cannot ing and the airway is clear, the test is successful.
assume that a hyperactive gag reflex is synonymous
with a functional cough. If the patient repeatedly coughs, chokes, or has a
positive aspirate, this is solid evidence that there is
5. The patient must have adequate cognition to attend inadequacy of swallowing, and the test should be
to feeding. terminated and no other food administered.
6. There cannot be any respiratory problem present, For patients who have been on a nasogastric tube
such as aspiration pneumonia, that might be and have demonstrated the ability to swallow water
compromised by additional aspiration. and pureed food without aspiration, proceed with
feeding the pureed food until at least three fourths
Procedures: of the jar has been consumed. For the next meal, or-
1. Place a small amount (1/2 teaspoon) of food on the der a tray of pureed food. Observe the patient during
eating; look for any problems and assess fatigue.
front of the tongue. Ask the patient to swallow, and
observe ability to manipulate food in the mouth to Use of a Mechanical Soft Diet: A mechanical soft
position it for swallowing. Allow the patient to place diet (ground meat, ground vegetables if fibrous or
the food in the mouth if possible because this will hard) should be substituted for regular-consistency
better coordinate feeding with the respiratory cycle. food for patients with any of the following: lack of
teeth or dentures, poor intraoral control for chewing,
2. If the patient cannot move the food in the mouth, fatigue during mastication (e.g., postpolio or Landry-
push it back slightly with a tongue blade, being Cuillain-Barre syndrome), limited jaw range of mo-
careful not to initiate a gag reflex. Ask the patient tion, limited attention span to complete the oral
to swallow, while lightly palpating the larynx to check preparatory phase.
laryngeal elevation.
3. Ask the patient to open the mouth, and check to see
that food has indeed been swallowed and that none
of it has pooled in the pharyngeal isthmus or oral
cavity.
4. To check for a clear airway, ask the patient to repeat
three sequential crisp sounds: "Agh, Agh, Agh." Any
3 4 0 Chapter 7 / Assessment of Muscles Innervated by Cranial Nerves
REFERENCES
Cited References 2 1 . Buthpitiya AG, Stroud D, Russell C O H . Pharyngeal
pump and esophageal transit. Dig Dis Sci
1. Williams PL, Warwick R Dyson M, ct al. Gray's Anatomy, 32:1244-1248, 1987.
38th ed. New York: Churchill Livingstone, 1995.
22. Kilman WJ, Goval RK. Disorders of pharyngeal and upper
2. Walsh FB. Walsh & Hoyt's Clinical Neuro Ophthalmology, esophageal sphincter motor function. Arch Intern Med
5th ed. Baltimore: Williams & Wilkins, 1998. 136:592-601, 1976.
3. Bender MB, Rudolph SH, Stacy CB. The neurology of Other Readings
the visual and oculomotor systems. In Joynt RJ (ed).
Clinical Neurology. Philadelphia: JB Lippincott, 1993. Cunningham DP, Basmajian JV. Electromyography of
genioglossus and geniohyoid muscles during deglutition.
4. Van Allen MW. Pictorial Manual of Neurologic Tests. Anat Rec 165:401-409, 1969.
Chicago: Year Book, 1969.
Gates J, Hartnell GG, Gramigna GD. Videofluoroscopy and
5. Haerer AF. Dejongs 'The Neurologic Examination, 5th ed. swallowing studies for neurologic disease: A primer.
Philadelphia: JB Lippincott, 1992. Radiographics 26:22, 2006.
6. Clemente CD. Gray's Anatomy, 30th ed. Philadelphia: Hrycyshyn AW, Basmajian IV. Electromyography of the
Lea & Febiger, 1991. oral stage of swallowing in man. Am J Anat
133:333-340, 1972.
7. Jenkins DB. Hollingshead's Functional Anatomy of the
limbs and Back, 7th ed. Philadelphia: WB Saunders, Isley CL, Basmajian JV. Electromyography of the human
1998. cheeks and lips. Anat Rec 176:143-147,' 1973.
8. DuBrul EL. Sicher and DuBrul's Oral Anatomy, 8th ed. Miller AJ. The Neuroscientific Principles of Swallowing and
St. Louis: Ishiyaku KuroAmerica, 1988. Dysphagia. (Dysphagia Series) San Diego: Singular
Publishing Group, 1998.
9. Nairn RI. The circumoral musculature: Structure and
function. Br Dent J 138:49-56, 1975. Palmer J B , Drennan JC, Baba M. Evaluation and treatment
of swallowing impairments. Am Fam Physician
10. Lightoller GH. Facial muscles: The modiolus and muscles 61:2453-2462, 2000.
surrounding the rima oris with remarks about the
panniculus adiposus. J Anat 60:1-85, 1925. Palmer JB, Tanaka E, Ensrud E Motion of the posterior
pharyngeal wall in human swallowing: A quantitative
11. Brodal A. Neurological Anatomy in Relation to Clinical videofluorographic study. Arch Phys Med Rehabil 11:1520-
Medicine. London: Oxford University Press, 1981. 1526, 2000.
12. Misuria VK. Functional anatomy of the tensor palatini Sonies BC. Dysphagia and post-polio syndrome: Past, present,
and levator palatini muscles. Ann Otolaryngol and future. Semin Neurol 16:365-370, 1996.
102:265, 1975.
Vitti M, Basmajian JV. Electromyographic investigation of
13. Keller JT, Saunders MC, Van Loveren H, Shipley ML procerus and frontalis muscles. Electromyogr Clin
Neuroanatomical considerations of palatal muscles: Neurophysiol 16:227-236, 1976.
Tensor and levator palatini. J Cleft Palate 2 1 : 7 0 - 7 5 , 1984.
Vitti M, Basmajian IV, Ouelette PL, et al. Electromyographic
14. Guyton AC. Textbook of Medical Physiology, 10th ed. investigation of the tongue and circumoral muscular sling
Philadelphia: WB Saunders, 2000. with fine-wire electrodes. ] Dent Res 54:844-849, 1975.
15. Miller AJ. Neurophysiological basis of swallowing. Wolf C, Meiners T H . Dysphagia in patients with acute cervical
Dysphagia 1:91-100, 1986. spinal cord injury. Spinal Cord 4 1 : 3 4 7 - 3 5 3 , 2003.
16. Doty R. Neural organization of deglutition. In Handbook Zablotny CM. Evaluation and management of swallowing
of Physiology, Section 6, Alimentary Canal. Washington, dysfunction. In Montgomery J. Physical Therapy
DC: American Physiologic Society, 1968. for Traumatic Brain Injury. New York: Churchill
Livingstone, 1995.
17. Statt JA. Manual techniques of chest physical therapy and
airway clearance techniques. In Zadai CC. Pulmonary Zafar H. Integrated jaw and neck function in man. Studies
Management in Physical Therapy. Clinics in Physical of mandibular and head-neck movements during jaw
Therapy. New York: Churchill Livingstone, 1992. opening-closing tasks. Swed Dent J Suppl 143:1-41, 2000.
18. Jacob P, Kahrilas PJ, Logemann JA, et al. Upper
esophageal sphincter opening and modulation during
swallowing. Gastroenterology 9 7 : 1 4 6 9 - 1 4 7 8 , 1989.
19. Logemann JA. Evaluation and Treatment of Swallowing
Disorders. San Diego: College-Hill Press, 1997.
20. Bosnia J. Deglutition: Pharyngeal stage. Physiol Rev
37:275-300, 1957.
Chapter 7 / Assessment of Muscles Innervated by Cranial Nerves 3 4 1
CHAPTER 8
Upright
Motor Control
The Test for Upright Control
Flexion Control Test
Extension Control Test
UPRIGHT MOTOR CONTROL
The manual muscle tests described in Chapters 2 (the pattern is named after the prevailing motion at
through 5 of this book are not germane to the eval- the elbow):
uation of muscle activity when there is dysfunction of
the central nervous system (CNS). In patients with Shoulder abduction or extension
CNS disorders, the muscles have normal innervation, Elbow flexion
but their control is disturbed because of damage to Forearm supination
the CNS, either in the brain or in the spinal cord. Wrist and finger flexion
These patients have upper motor neuron disorders It is also common to see an extensor pattern of
that are characterized by one or any combination of motion in the lower extremity:
the following: Hip extension
Knee extension
Abnormal limb movement patterns Plantar flexion and inversion
Disturbed muscle tone (spasticity, rigidity) These patterns are fairly stereotyped, but studies
Aberrations in the selection, amplitude, or timing of reveal multiple variations in the participating muscles
and their amplitude in a "typical" flexion or extensor
synergistic muscle activity, duration, and rate pattern.3-5
(velocity) of activity in individual muscles The upright motor control test was designed to
incorporate the effects of upright posture and weight
Impaired tactile sensation: paresthesias, anesthesias, bearing.2 It simulates the activity required for walk-
or hypesthesias ing (i.e., flexion, which includes the factor of speed,
and extension, which assesses joint stability). Inter-
Disturbed proprioception and kinesthesia tester reliability has been established at 96 percent
Impaired spatial discrimination agreement for the flexion portion of the test and 90
Impaired body image percent agreement for the extension portion of the test.2
Disturbed central balance mechanisms and abnormal Validity with respect to prediction of gait per-
formance from test data has not been published.
postural reactions
Abnormal reflex activity THE TEST FOR UPRIGHT CONTROL
Analysis of a patient with some combination of One examiner and an assistant are required to con-
these problems is a complex task. Manual muscle duct this evaluation properly. The assistant should be
testing was not designed for such patients and should a physical therapist or a person who has received ex-
not be used to evaluate t h e m . 1 Manual muscle test- tensive instruction in methods of positioning himself
ing was (and is) designed to evaluate patients with a or herself and the patient to provide appropriate
lower motor neuron disorder manifested by flaccid (neither too little nor too much) stabilization and
weakness or paralysis. Its use in patients with C N S support. T h e patient must be able to understand all
dysfunction yields spurious clinical results that have test instructions, as verified by appropriate responses
little or no relevance to function. Indeed, muscle to verbal commands or demonstration. The patient
testing scores in patients with lower motor neuron also must require no more than the assistance of
disorders do not necessarily relate to, or predict, one person for either single-limb or double-limb
function. stance.
An obvious exclusion from this blanket assertion is The test itself has two major sections: the flexion
patients with both CNS and lower motor neuron dis- control test and the extension control test. Each of
orders. Two good examples are the patient with a these sections has three parts, one each for the hip,
spinal cord injury and the patient with amyotrophic knee, and ankle.
lateral sclerosis.
FLEXION CONTROL TEST
Evaluation of muscle performance, however, is an (IN PARTS 1, 2, AND 3)
important tool of the physical therapist in treating
the patient with CNS derangement. One such tool The purpose of this portion of the upright motor
was developed to test lower extremity control during control test is to ascertain flexion control of the
standing.2 It can be used in patients who have selec- non-weight-bearing extremity (i.e., for limb ad-
tive control, patterned motion, or a combination of vancement in the swing phase of gait).
the two.
The test is conducted bilaterally unless there is un-
Selective control is the ability to move a single joint equivocal evidence that one side is without neuro-
without activating movement in an adjacent or
neighboring joint of the same extremity. For exam-
ple, the patient should be able to flex the elbow
without incurring simultaneous motion at the should-
er or wrist.
Patterned motion is the inability to perform a frac-
tionated motion (e.g., wrist extension without move-
ment at the elbow or fingers). For example, following
a stroke or brain injury a flexor pattern of move-
ment is common in the upper extremity, as follows
344 Chapter 8 / Upright Motor Control
UPRIGHT MOTOR CONTROL
logic deficit. The assistant provides manual balance Part 2: Knee Flexion
support by holding the patient's hand, positioning
his or her arm so that the hand is at about the level Instructions to Patient: "Stand as straight as you
of the greater trochanter. The support is given on can. Bring your knee up toward your chest three
the side contralateral to that being tested and should times, as high and as fast as you can."
be sufficient for the patient to maintain standing bal-
ance during this segment of the test. Grading: See Table 8-2.
For the patient who has bilateral lower extremity Table 8-2 K N E E F L E X I O N
involvement, external stabilization for contralateral hip
and knee extension may be required during the Score Criteria
single-limb flexion test. This can be done manually Weak (W)
by preventing knee flexion and holding the patient in No motion, or knee flexes less
hip extension; an external support such as a "knee Moderate (M) than 30°.
immobilizer" may be used. Completes three repetitions
Strong (S) through any range but requires,
The examiner may stand in front of and facing the as a group, more than 10 sec.
patient, or, if the patient has side confusion, he or
she may stand slightly in front but facing in the same Actively completes an arc of
direction. The examiner demonstrates each test part knee flexion from 0° to between
as many times as necessary to ensure patient under- 30° and 60° three times within
standing. The patient then is allowed no more than 10 sec,
two practice trials to avoid fatigue.
Knee flexes more than 60° three
The actual data collection (graded trial) is limited times within 10 sec.
to one trial per limb segment. Just before grading,
the patient's test limb should be positioned in neu-
tral at both hip and knee (0° at the hip and 0° at the
knee). If the patient cannot reach neutral, a position
of maximal extension range should be used.
Part 1: Hip Flexion Part 3: Ankle Flexion (Dorsiflexion)
Instructions to Patient: "Stand as straight as you Instructions to Patient: "Stand as straight as you
can. Bring your knee up toward your chest, as high can. Bring your knee and foot up toward your chest
and as fast as you can." as high and as fast as you can."
Grading: T h e hip flexion motion must occur at the Grading: See Table 8-3.
hip joint. Do not allow substitution or other contam-
ination of the motion such as backward lean or pelvic
tilt (Table 8-1).
Table 8-3 D O R S I F L E X I O N
Table 8-1 H I P F L E X I O N Score Criteria
Weak (W)
Score Criteria No motion, or actively
Weak (W) Moderate (M) dorsiflexes to less than a right
No motion, or patient actively Strong (S) angle. (Examiner is cautioned
Moderate (M) flexes less than 30°. not to confuse forefoot or toe
Three repetitions through any extension with true ankle
Strong (S) range that requires, as a group, motion.) Completes three
more than 10 sec to complete, repetitions through any range
but requires, as a group, more
Actively completes an arc of hip than 10 sec.
flexion from 0° (or maximal
extension angle) to between This grade is not used because
30° and 60° three times within range of dorsiflexion is so limited
10 sec, and very little dorsiflexion is
used in the swing phase of gait.
Actively completes an arc of
hip flexion from 0° (or maximal Actively dorsiflexes to a right
extension angle) to more than angle or greater three times in
60° three times within 10 sec. 10 sec.
Chapter 8 / Upright Motor Control 345
UPRIGHT MOTOR CONTROL
EXTENSION CONTROL TEST (IN PARTS 4, 5, AND 6)
The purpose of this portion of the upright motor The assistant helps to stabilize or provide hand
control test is to ascertain extension control of a sin- support as described under each test part.
gle weight-bearing extremity (i.e., for single-limb
stance in gait). If the patient has a fixed equinus contracture that
is greater than the neutral ankle position, the con-
Instructions and procedures for the test are similar tracture must be accommodated by placing a hard
to those used in the flexion control test. The exam- wedge under the heel. The purpose of the wedge is
iner demonstrates each segment sufficiently to ensure to align the tibia into a vertical position.
patient understanding but allows only two practice
trials per segment to avoid fatigue. Only one graded If a stable plantigrade platform cannot be main-
trial per segment is permitted. tained (with manual support or with an ankle-foot
orthosis), the examiner should give a score of UT
The starting position for this test is a double-limb (Unable to Test) at the hip and knee. The ankle
stance with both limbs in neutral alignment or the score should be noted as E (Excessive). That is to
patient's maximal available extension range. The pa- say, if excessive tone precludes the foot from assum-
tient is required to bring the nontest limb off the ing a position flat on the floor, the extension control
floor; if this is not possible, help in flexing the non- test cannot be conducted.
test limb should be provided by the assistant.
346 Chapter 8 / Upright Motor Control
UPRIGHT MOTOR CONTROL
Part 4: Hip Extension Instructions to Patient: "Stand on both legs as
straight as you can."
Positioning and Stabilization: The examiner is po-
sitioned beside the patient to offer hand support and "Now stand as straight as you can on just your
to ensure that the patient begins from a position of right/left leg." (Note: This is the weaker limb if the
neutral alignment or from the patient's maximal hip test is to be unilateral.)
extension range (Figure 8-1).
"Lift this leg up [point to or touch desired
The assistant provides manual stabilization to leg] . . . keep standing as straight as you can."
maintain neutral knee extension and a stable ankle.
Remember that plantigrade positioning of the foot is Grading: W h e n the patient is balanced on the test
required. limb, the examiner gradually decreases the amount of
hand support to determine the degree of hip control
(Table 8-4).
Table 8-4 H I P F L E X I O N
Score Criteria
Weak (W)
Moderate (M) Uncontrolled trunk flexion on
hip occurs, (Examiner must
Strong (S) prevent continued forward
motion of the trunk by
providing additional hand
support.)
Patient is unable to maintain
trunk completely erect or at
the end of the available hip
extension range. The patient is,
however, able to stop the
forward trunk momentum.
Alternatively, the trunk wobbles
back and forth or the patient
hyperextends the trunk on the
hip.
Patient maintains trunk erect or
at the end of the available hip
extension range.
FIGURE 8-1 Hip extension test. The patient, aligned in
neutral, raises the nontest limb. The examiner (on
patient's right) maintains trunk and limb alignment in
neutral, and if the knee or ankle or both are unstable,
manual support is provided by the assistant, as
illustrated,
Chapter 8 / Upright Motor Control 347
UPRIGHT MOTOR CONTROL
Part 5: Knee Extension I n s t r u c t i o n s to P a t i e n t : "Stand on both feet with
your knees bent. Keep your knees bent and lift your
Positioning and Stabilization: T h e assistant is posi- right/left leg." (Note: T h e raised leg should be the
tioned behind the patient to provide hand support stronger limb.)
for balance and to maintain the trunk erect on the
hip (Figure 8-2). If the patient can support body weight on a flexed
knee during single-limb support without further col-
T h e examiner positions the patient's knees in 30° lapse into flexion, proceed to the test for Strong ( S )
of flexion bilaterally. If the patient is unable to main- (Table 8-5).
tain both feet flat on the floor with approximately
30° of knee flexion, a hard wedge should be placed Grading: See Table 8 - 5 . When a knee flexion con-
under the heel to compensate for the limited dorsi- tracture is present, the grade awarded can never ex-
flexion range of motion. ceed Moderate ( M ) .
Table 8-5 K N E E E X T E N S I O N
Score Criteria
Weak (W)
Patient is unable to maintain
Moderate (M) body weight on a flexed knee;
Strong (S) therefore the knee continues to
collapse into flexion or the heel
Excessive (E) rises.
Unable to
Test (UT) Patient supports body weight
on a flexed knee without either
FIGURE 8-2 Knee extension test, The patient stands further collapse into flexion or
with both feet in plantigrade position. The examiner, heel rise.
kneeling in front, gives manual cues to the patient
to flex both knees to 30°. The assistant stands behind Patient supports body weight
the patient to offer balance support to one of the on a flexed knee and on
patient's hands and uses the other hand to cue the request straightens that knee
patient to maintain erect posture. to the end of available knee
extension range. Hyperextension
is allowed.
It is not possible to position the
knee in flexion because of
severe extensor thrust or
extensor tone.
Absence of plantigrade foot or
other condition renders test
invalid.
348 Chapter 8 / Upright Motor Control
UPRIGHT MOTOR CONTROL
Part 6: Ankle Extension (Plantar Flexion) T h e passive range of ankle motion must be mea-
sured with the knee extended. If necessary, accom-
T h e purpose of this part of the extension test is to modate lack of dorsiflexion range (as occurs with a
identify ankle control relative to maintaining a verti- plantar flexion contracture) by placing a hard wedge
cal tibial position. under the heel. T h i s w i l l place the ankle in more
plantar flexion, thus providing some relative dorsiflex-
If the patient has a knee flexion contracture in the ion range for the purpose of this test.
test limb, the test cannot be conducted in a correct
manner. W i t h the knee flexed, the quadriceps muscle I n s t r u c t i o n s to Patient: "Stand on both legs as
group can maintain single-limb stance despite the straight as you can. L i f t and hold up your right/left
presence or absence of activity at the ankle. leg." (Note: T h e raised leg should be the stronger
limb.)
Positioning and Stabilization: T h e assistant is posi-
tioned behind the patient to maintain the trunk in an If the patient can control the tibia with the knee
erect posture over the hip (Figure 8 - 3 ) . T h e examiner in neutral, proceed to ask for a heel rise while the
is positioned to prevent knee hyperextension (i.e., knee is kept at 0°:
ankle plantar flexion).
"Keep your knee straight and go up on your toes
as high as you can."
Grading: See Table 8-6.
Table 8-6 P L A N T A R F L E X I O N
FIGURE 8-3 Ankle extension test. The patient stands Score Criteria
erect in plantigrade position, and then raises the Weak (W)
nontest limb. The examiner kneels alongside or slightly Patient is unable to maintain
behind to keep the knee from hyperextending. The Moderate (M) knee in neutral position; knee
assistant stands behind the patient to offer balance Strong (S) collapses into flexion and the
support and to cue the patient to maintain erect Excessive (E) ankle into dorsiflexion so that
posture. Unable to the tibia is displaced forward.
Test (UT) Alternatively, the knee or ankle
segment wobbles back and
forth between flexion and
extension or hyperextension. The
presence of an extensor thrust
that cannot be controlled by
examiner also may indicate
lack of adequate ankle control.
Patient can control the knee in
a neutral (0°) position and the
ankle in a neutral (90°) position
so that the tibia is vertical.
Patient maintains knee at
neutral and lifts heel off floor on
command, (Any degree of heel
rise while maintaining the knee
at neutral is acceptable.)
Severity of equinus or varus is
so great that patient cannot
maintain a stable plantigrade
ankle.
Patient has a knee flexion
contracture.
Chapter 8 / Upright Motor Control 349
REFERENCES
1. Lovett RW, Martin EG. Certain aspects of infantile paralysis 4. Sawner K, LaVigne JM. Brunnstrom's Movement Therapy
and a description of a method of muscle testing. JAMA in Hemiplegia. Philadelphia: IB Lippincott, 1992.
66:729-733, 1916.
5. Knutsson E, Richards C. Different types of disturbed motor
2. Montgomery I. Assessment and treatment of locomotor control in gait of hemiparetic patients. Brain 102:405-430,
deficits in stroke. In Duncan P, Radke M (eds). Stroke 1979.
Rehabilitation. St Louis: Mosby, 1987.
3. Perry J, Giovan P, Harris LJ, et al. The determinants of
muscle action in the hemiparetic lower extremity. Clin
Orthop 131:71-89, 1978.
350 Chapter cS / Upright Motor Control
CHAPTER 9
Ready
Reference
Anatomy
Part 1. Alphabetical List of Muscles
USING THIS READY REFERENCE turn may help the reader to recall more detailed
anatomy.
This chapter of the book, is intended as a quick
source of information about muscles, their anatomi- Nomina Anatomica nomenclature for the muscles
cal description, participation in motions, and inner- appears in brackets when a more common usage is
vation. This information is not intended to be compre- listed.
hensive, and for depth of subject matter the reader is
referred to any of the major texts of human anatomy. Muscle Reference (ID) Numbers
We relied on the American1 and British2 versions of
Gray's Anatomy as principal references but also used Each skeletal muscle in the body has been given a
Sobotta's Atlas,3 C l e m e n t e , 4 Netter,5 H o l l i n g s h e a d , 6 number that is used with that muscle throughout
Jenkins,6 Grant,7 and Moore,8 among others. The fi- the book. The order of numbering is derived from
nal arbiter in all cases was the 3 8 t h edition of Gray's the regional sequence of muscles used in part 2 of this
Anatomy (British) by Williams et al. reference. The numbering should, however, permit the
reader to refer quickly to any one of the summaries
The variations in text descriptions of individual or to cross-check information between summaries. In
muscles remain exceedingly diverse so at times we the first part of the ready reference section (and also
have consolidated information to provide abstracted inside the front cover), the muscles are listed in
descriptions. alphabetical order, and this is followed by a list of
muscles by region (also inside the back cover). In each
Origins, insertions, descriptions, and functions muscle test, the participating muscles also are preceded
of individual muscles often are abbreviated but by their assigned identification (reference) number.
should allow the reader to place the muscle correct-
ly and visualize its most common actions; this in
PART 1 ALPHABETICAL LIST OF MUSCLES
Ac
159 Abductor digiti minimi (hand) 34 Chondroglossus
215 Abductor digiti minimi (foot) 116 Coccygeus
224 Abductor hallucis 139 Coracobrachialis
171 Abductor pollicis brevis
166 Abductor pollicis longus 5 Corrugator supercilii
180 Adductor brevis 50 Cricothyroid [Cricothyroideus]
225 Adductor hallucis 117 Cremaster
179 Adductor longus
181 Adductor magnus D
173 Adductor pollicis
144 Anconeus 133 Deltoid [Deltoideus]
23 Depressor anguli oris
27 Auriculares 24 Depressor labii inferioris
201 Articularis genus 14 Depressor septi
B 101 Diaphragm
78 Digastric [Digastricus]
140 Biceps brachii
192 Biceps femoris E
141 Brachialis
143 Brachioradialis 2 Epicranius
149 Extensor carpi radialis brevis
26 Buccinator 148 Extensor carpi radialis longus
120 Bulbospongiosus 150 Extensor carpi ulnaris
158 Extensor digiti minimi
3 5 2 Chapter 9 / Ready Reference Anatomy
154 Extensor digitorum Part 1. Alphabetical List of Muscles
212 Extensor digitorum brevis
211 Extensor digitorum longus 89 Iliocostalis thoracis
221 Extensor hallucis longus 90 Iliocostalis lumborum
155 Extensor indicis 41 Inferior pharyngeal constrictor [Constrictor
168 Extensor pollicis brevis
167 Extensor pollicis longus pharyngis inferior]
38 Inferior longitudinal (tongue) [Longitudinalis
F
inferior]
151 Flexor carpi radialis 84-87 Infrahyoids (see Sternothyroid, Thyrohyoid,
153 Flexor carpi ulnaris
160 Flexor digiti minimi brevis (hand) Sternohyoid, Omohyoid)
216 Flexor digiti minimi brevis (foot) 136 Infraspinatus
214 Flexor digitorum brevis 102 Intercostales externi
213 Flexor digitorum longus 103 Intercostales interni
157 Flexor digitorum profundus 104 Intercostales intimi
156 Flexor digitorum superficialis 164 Interossei, dorsal (hand) [Interossei dorsales]
223 Flexor hallucis brevis 219 Interossei, dorsal (foot) [Interossei dorsales]
222 Flexor hallucis longus 165 Interossei, palmar or volar [Interossei
170 Flexor pollicis brevis
169 Flexor pollicis longus palmares]
220 Interossei, plantar [Interossei plantares]
G
69 Interspinals cervicis
205 Gastrocnemius 97 Interspinales thoracis
190 Gemellus inferior 98 Interspinales lumborum
189 Gemellus superior 70 Intertransversarii cervicis
99 Intertransversarii thoracis
32 Gcnioglossus 99 Intertransversarii lumborum
77 Geniohyoid [Geniohyoideus] 121 Ischiocavernosus
182 Gluteus maximus
183 Gluteus medius L
184 Gluteus minimus
178 Gracilis 52 Lateral cricoarytenoid [Cricoarytenoideus
lateralis]
H
30 Lateral pterygoid [Pterygoideus lateralis]
33 Hyoglossus 130 Latissimus dorsi
115 Levator ani
I
17 Levator anguli oris
176 Iliacus 15 Levator labii superioris
66 Iliocostals cervicis 16 Levator labii superioris alaeque nasi
3 Levator palpebrae superioris
127 Levator scapulae
46 Levator veli palatini
107 Levatores costarum
60 Longissimus capitis
64 Longissimus cervicis
91 Longissimus thoracis
Chapter 9 / Ready Reference Anatomy 3 5 3
Part 1. Alphabetical List of Muscles 177 Pectineus
131 Pectoralis major
74 Longus capitis 129 Pectoralis minor
79 Longus colli 209 Peroneus brevis
163 Lumbricales (hand) [Lumbricals] 208 Peroneus longus
218 Lumbricales (foot) [Lumbricals] 210 Peroneus tertius
186 Piriformis
M 207 Plantaris
28 Masseter 88 Platysma
31 Medial pterygoid [Pterygoideus medialis] 202 Popliteus
21 Mentalis
42 Middle pharyngeal constrictor [Constrictor 51 Posterior cricoarytenoid [Cricoarytenoideus
posterior]
pharyngis medius]
94 Multifidi 12 Procerus
48 Musculus uvulae 147 Pronator quadratus
75 Mylohyoid [Mylohyoideus] 146 Pronator teres
174 Psoas major
N 175 Psoas minor
114 Pvramidalis
13 Nasalis
Q
o
191 Quadratus fenioris
54 Oblique arytenoid [Arytenoideus obliquus] 100 Quadratus lumborum
59 Obliquus capitis inferior 217 Quadratus plantae
58 Obliquus capitis superior
110 Obliquus externus abdominis 196-200 Quadriceps femoris (see Rectus femoris,
11 Obliquus inferior oculi Vastus intermedins, Vastus medialis
111 Obliquus internus abdominis longus, Vastus medialis oblique, Vastus
10 Obliquus superior oculi lateralis)
188 Obturator externus [Obturatorius externus]
187 Obturator internus [Obturatorius internus] R
1 Occipitofrontalis 113 Rectus abdominis
87 Omohyoid [Omohyoideus] 72 Rectus capitis anterior
161 Opponens digiti minimi 73 Rectus capitis lateralis
172 Opponens pollicis 56 Rectus capitis posterior major
57 Rectus capitis posterior minor
4 Orbicularis oculi
25 Orbicularis oris 196 Rectus femoris
7 Rectus inferior
P 9 Rectus lateralis
8 Rectus medialis
36 Palatoglossus 6 Rectus superior
49 Palatopharyngeus
162 Palmaris brevis 125 R h o m b o i d major [Rhomboideus major]
152 Palmaris longus 126 Rhomboid minor [ Rhomboideus minor]
3 5 4 Chapter 9 / Ready Reference Anatomy
20 Risorius Part 1. Alphabetical List of Muscles
71 Rotatores cervicis
96 Rotatores lumborum 145 Supinator
95 Rotatores thoracis 75-78 Suprahyoids (see Mylohyoid, Stylohyoid,
s Geniohyoid, Digastric)
135 Supraspinatus
45 Salpingopharyngeus
195 Sartorius T
80 Scalenus anterior 29 Temporalis
81 Scalenus medius 2 Temporoparietalis
82 Scalenus posterior
194 Semimembranosus 185 Tensor fasciae latae
62 Semispinalis capitis 47 Tensor veli palatini
65 Semispinalis cervicis
93 Semispinalis thoracis 138 Teres major
193 Semitendinosus 137 Teres minor
128 Serratus anterior
109 Serratus posterior inferior 85 Thyrohyoid [Thyrohyoideus]
108 Serratus posterior superior 55 Thyroarytenoid [Thyroarytenoideus]
206 Soleus 203 Tibialis anterior
123 Sphincter ani externus 204 Tibialis posterior
122 Sphincter urethrae 39 Transverse lingual [Transversus linguae]
63 Spinalis capitis 112 Transversus abdominis
68 Spinalis cervicis 53 Transverse arytenoid [Arytenoideus
92 Spinalis thoracis
61 Splenius capitis transversus]
67 Splenius cervicis 22 Transversus menti
83 Sternocleidomastoid [Sternocleidomastoideus] 119 Transversus perinei profundus
86 Sternohyoid [Sternohyoideus] 118 Transversus perinei superficialis
84 Sternothyroid [Sternothyroideus] 106 Transversus thoracis
35 Styloglossus 124 Trapezius
76 Stylohyoid [Stylohyoideus] 142 Triceps brachii
44 Stylopharyngeus
132 Subclavius u
105 Subcostales
134 Subscapularis 48 Uvula (see Musculus uvulae)
43 Superior pharyngeal constrictor [Constrictor
V
pharyngis superior]
37 Superior longitudinal (tongue) [Longitudinalis 198 Vastus intermedius
199 Vastus medialis longus
superior] 200 Vastus medialis oblique
197 Vastus lateralis
40 Vertical lingual [Verticalis linguae]
z
18 Zygomaticus major
19 Zygomaticus minor
Chapter 9 / Ready Reference Anatomy 3 5 5
PART 2. LIST OF MUSCLES BY REGION
HEAD AND FOREHEAD EAR
1 Occipitofrontalis 27 Auriculares
2 Temporoparietalis
JAW (MASTICATION)
EYELIDS
28 Masseter
3 Levator palpebrae superioris 29 Temporalis
4 Orbicularis oculi 30 Lateral pterygoid
5 Corrugator supercilii 31 Medial pterygoid
OCULAR MUSCLES TONGUE
6 Rectus superior 32 Genioglossus
7 Rectus inferior 33 Hyoglossus
8 Rectus medialis 34 Chondroglossus
9 Rectus lateralis 35 Styloglossus
10 Obliquus superior 36 Palatoglossus
11 Obliquus inferior 37 Superior longitudinal
38 Inferior longitudinal
NOSE 39 Transverse lingual
40 Vertical lingual
12 Procerus
13 Nasalis PHARYNX
14 Depressor septi
41 Inferior pharyngeal constrictor
MOUTH 42 Middle pharyngeal constrictor
43 Superior pharyngeal constrictor
15 Levator labii superioris 44 Stylopharyngeus
16 Levator labii superioris alaeque nasi 45 Salpingopharyngeus
17 Levator anguli oris 49 Palatopharyngeus (see under Palate)
18 Zygomaticus major
19 Zygomaticus minor PALATE
20 Risorius
21 Mentalis 46 Levator veli palatini
22 Transversus menti 47 Tensor veli palatini
23 Depressor anguli oris 48 Musculus uvulae
24 Depressor labii inferioris 36 Palatoglossus (see under Tongue)
25 Orbicularis oris 49 Palatopharyngeus
26 Buccinator
3 5 6 Chapter 9 / Ready Reference Anatomy
LARYNX Part 2. List of Muscles by Region
50 Cricothyroid 84 Sternothyroid
51 Posterior cricoarytenoid 85 Thyrohyoid
52 Lateral cricoarytenoid 86 Sternohyoid
53 Transverse arytenoid 87 Omohyoid
54 Oblique arytenoid 88 Platysma
55 Thyroarytenoid
55a Vocalis BACK
55b Thyroepiglotticus
61 Splenius capitis (see under Neck)
NECK 67 Splenius cervicis (see under Neck)
66 Iliocostalis cervicis (see under Neck)
56 Rectus capitis posterior major 89 Iliocostalis thoracis
57 Rectus capitis posterior minor 90 Iliocostalis lumborum
58 Obliquus capitis superior 60 Longissimus capitis (see under Neck)
59 Obliquus capitis inferior 64 Longissimus cervicis (see under Neck)
60 Longissimus capitis 91 Longissimus thoracis
61 Splenius capitis 63 Spinalis capitis
62 Semispinalis capitis 68 Spinalis cervicis
63 Spinalis capitis 92 Spinalis thoracis
64 Longissimus cervicis 62 Semispinalis capitis (see under Neck)
65 Semispinalis cervicis 65 Semispinalis cervicis (see under Neck)
66 Iliocostalis cervicis 93 Semispinalis thoracis
67 Splenius cervicis 94 Multifidi
68 Spinalis cervicis 71 Rotatores cervicis
69 Interspinales cervicis 95 Rotatores thoracis
70 Intertransversarii cervicis 96 Rotatores lumborum
71 Rotatores cervicis 69 Interspinales cervicis
72 Rectus capitis anterior 97 Interspinales thoracis
73 Rectus capitis lateralis 98 Interspinales lumborum
74 Longus capitis 70 Intertransversarii cervicis
75 Mylohyoid 99 Intertransversarii thoracis
76 Stylohyoid 99 Intertransversarii lumborum
77 Geniohyoid 100 Quadratus l u m b o r u m
78 Digastricus
79 Longus colli THORAX (RESPIRATION)
80 Scalenus anterior
81 Scalenus medius 101 Diaphragm
82 Scalenus posterior 102 Intercostales externi
83 Sternocleidomastoid 103 Intercostales interni
104 Intercostales intimi
105 Subcostales
Chapter 9 / Ready Reference Anatomy 3 5 7
Part 2. List of Muscles by Region 133 Deltoid
134 Subscapularis
106 Transversus thoracis 135 Supraspinatus
107 Levatores costarum 136 Infraspinatus
108 Serratus posterior superior 137 Teres minor
109 Serratus posterior inferior 138 Teres major
139 Coracobrachialis
ABDOMEN
Elbow
110 Obliquus externus abdominis
111 Obliquus internus abdominis 140 Biceps brachii
112 Transversus abdominis 141 Brachialis
113 Rectus abdominis 142 Triceps brachii
114 Pyramidalis 143 Brachioradialis
144 Anconeus
PERINEUM
Forearm
115 Levator ani
116 Coccygeus 145 Supinator
117 Cremaster 146 Pronator teres
118 Transversus perinei superficialis 147 Pronator quadratus
119 Transversus perinei profundus 140 Biceps brachii (see under Elbow)
120 Bulbospongiosus
121 Ischiocavernosus Wrist
122 Sphincter urethrae
123 Sphincter ani externus 148 Extensor carpi radialis longus
149 Extensor carpi radialis brevis
UPPER EXTREMITY 150 Extensor carpi ulnaris
Shoulder Girdle 151 Flexor carpi radialis
152 Palmaris longus
124 Trapezius 153 Flexor carpi ulnaris
125 Rhomboid major
126 Rhomboid minor Fingers
127 Levator scapulae
128 Serratus anterior 154 Extensor digitorum
129 Pectoralis minor 155 Extensor indicis
156 Flexor digitorum superficialis
Vertebrohumeral 157 Flexor digitorum profundus
163 Lumbricales
130 Latissimus dorsi 164 Interossei, dorsal
131 Pectoralis major 165 Interossei, palmar
Shoulder Little Finger and Hypothenar Muscles
132 Subclavius 158 Extensor digiti minimi
159 Abductor digiti minimi
3 5 8 Chapter 9 / Ready Reference Anatomy
160 Flexor digiti minimi brevis Part 2. List of Muscles by Region
161 Opponens digiti minimi
162 Palmaris brevis Knee
Thumb and Thenar Muscles 196-200 Quadriceps femoris
196 Rectus femoris
166 Abductor pollicis longus 197 Vastus lateralis
167 Extensor pollicis longus 198 Vastus intermedius
168 Extensor pollicis brevis 199 Vastus medialis longus
169 Flexor pollicis longus 200 Vastus medialis oblique
170 Flexor pollicis brevis
171 Abductor pollicis brevis 201 Articularis genus
172 Opponens pollicis 192 Biceps femoris
173 Adductor pollicis 193 Semitendinosus
194 Semimembranosus
LOWER EXTREMITY 202 Popliteus
Hip and Thigh Ankle
174 Psoas major 203 Tibialis anterior
175 Psoas minor 204 Tibialis posterior
176 Iliacus 205 Gastrocnemius
177 Pectineus 206 Soleus
178 Gracilis 207 Plantaris
179 Adductor longus 208 Peroneus longus
180 Adductor brevis 209 Peroneus brevis
181 Adductor magnus 210 Peroneus tertius
182 Gluteus maximus
183 Gluteus medius Lesser Toes
184 Gluteus minimus
185 Tensor fasciae latae 211 Extensor digitorum longus
186 Piriformis 212 Extensor digitorum brevis
187 Obturator internus 213 Flexor digitorum longus
188 Obturator externus 214 Flexor digitorum brevis
189 Gemellus superior 215 Abductor digiti minimi
190 Gemellus inferior 216 Flexor digiti minimi brevis
191 Quadratus femoris 217 Quadratus plantae
192 Biceps femoris 218 Lumbricales
193 Semitendinosus 219 Interossei, dorsal
194 Semimembranosus 220 Interossei, plantar
195 Sartorius
Great Toe (Hallux)
221 Extensor hallucis longus 359
222 Flexor hallucis longus
223 Flexor hallucis brevis
224 Abductor hallucis
225 Adductor hallucis
Chapter 9 / Ready Reference Anatomy
PART 3. SKELETAL MUSCLES OF THE HUMAN BODY
HEAD 360 Frontal Part (Frontalis)
Scalp (forehead)
Eyelids 360
Ocular 3 6 1 Origin:
Nose 362 Superficial fascia over scalp
Mouth 364 No bony attachments
Jaw (mastication) 365 Median fibers continuous with procerus
Ear 3 6 9 Intermediate fibers join corrugator supercilii and
Tongue 369 orbicularis oculi
Pharynx 371 Lateral fibers also join orbicularis oculi
Palate
Larynx 372
NECK 3 7 4 Insertion:
375 Galea aponeurotica
TRUNK 3 7 6 Skin of eyebrows and root of nose
Back
Respiration 3 8 4 Description:
Abdomen
Perineum 384 Overlies the cranium from the eyebrows to the
UPPER EXTREMITY 388 superior nuchal line on the occiput. The
Scapula 391 epicranius consists of the occipitofrontalis with
Vertebrohumeral 3 9 3 its four thin branches on either side of the
Scapulohumeral head; the broad aponeurosis called the galea
Elbow. 3 9 7 aponeurotica; and the temporoparietalis with
Forearm 3 9 7 its two slim branches. The medial margins of
Wrist 399 the two bellies join above the nose and run to-
Fingers 4 0 0 gether upward and over the forehead.
Thumb 402
403 The galea aponeurotica covers the cranium be-
LOWER EXTREMITY tween the frontal belly and the occipital belly of
Hip and thigh 4 0 4 the epicranius and between the two occipital
Knee 4 0 6 bellies over the occiput. It is adhered closely to
Ankle 4 1 1 the dermal layers (scalp), which allows the scalp
Lesser toes
Great toe 4 1 3 to be moved freely over the cranium.
MUSCLES OF THE FOREHEAD 413
4 1 9 Function:
The Epicranius (Two Muscles) 4 2 1 Contracting together, both bellies draw the scalp
4 2 3 up and back, thus raising the eyebrows (sur-
1 Occipitofrontalis 4 2 6 prise!) and assisting with wrinkling the forehead.
2 Temporoparietalis Working alone, the frontal belly raises the eyebrow
1 OCCIPITOFRONTALIS on the same side.
Muscle has two parts Innervation:
Facial (VII) nerve
Occipital Part (Occipitalis) Temporal branches: to frontalis
Posterior auricular branch: to occipitalis
Origin:
Occiput (superior nuchal line, lateral 2 / 3 ) 2 TEMPOROPARIETALIS
Temporal bone (mastoid process)
Origin:
Insertion: Temporal fascia (superior and anterior to external
Galea aponeurotica ear, then fanning out and up over temporal
fascia)
Insertion: high on
Galea aponeurotica (lateral border)
Into skin and temporal fascia somewhere
lateral side of head
Description:
A thin broad sheet of muscle in two bellies that lie
on either side of head. Highly variable. See also
description of occipitofrontalis.
3 6 0 Chapter 9 / Ready Reference Anatomy
Part 3. Skeletal Muscles of the Human Body
Function: Origin:
Tightens scalp
Draws back skin over temples Orbital part:
Raises auricula of the ear
In concert with occipitofrontalis, raises the eye- Frontal bone (nasal part)
brows, widens the eyes, and wrinkles the skin of
the forehead (in expressions of surprise and Maxilla (frontal process in front of lacrimal
fright)
groove)
Innervation:
Facial (VII) nerve (temporal branches) Medial palpebral ligament
MUSCLES OF THE EYELIDS Palpebral part:
AND EYEBROWS
Medial palpebral ligament
3 Levator palpebrae superioris
Frontal bone just in front of and below the
4 Orbicularis oculi
palpebral ligament
5 Corrugator supercilii
Lacrimal part:
3 LEVATOR PALPEBRAE SUPERIORIS
Lacrimal fascia
Origin:
Sphenoid bone (inferior surface of lesser wing) Lacrimal bone (crest and lateral surface)
Roof of orbital cavity
Insertion:
Insertion:
Into several lamellae: Orbital part: T h e fibers blend with nearby mus-
Aponeurosis of the orbital septum cles (occipitofrontalis and corrugator super
Superior tarsus (a small, thin, smooth fiber mus- cilii). Some fibers also insert into skin of
cle on the inferior surface of the levator eyebrow.
palpebrae and skin of eyelids)
Upper eyelid skin Palpebral part: Lateral palpebral raphe.
Sheath of the rectus superior (and with it, blends Lacrimal part: Superior and inferior tarsi of the
with the superior fornix of the conjunctiva)
eyelids. Fibers form lateral palpebral raphe.
Description:
Thin and flat muscle lying posterior and superior Description:
to the orbit. At its origin it is tendinous, broad- Forms a broad thin layer that fills the eyelids (see
ening out to end in a wide aponeurosis that Figure 7-13) and surrounds the circumference of
splits into three lamellae. Connective tissue of the orbit but also spreads over the temple and
the levator fuses with adjoining connective tis- cheek. Orbital fibers form complete ellipses. On
sue of the rectus superior and this aponeurosis the lateral side there are no bony attachments.
can be traced laterally to a tubercle of the The upper orbital fiber ellipses blend with the
zygomatic bone and medially to the medial occipitofrontalis and corrugator supercilii mus-
palpebral ligament. cles. Fibers also insert into the skin of the eye-
brow, forming a depressor supercilii. Medially
Function: some ellipses reach the procerus.
Raises upper eyelid
The inferior orbital ellipses blend with the levator
Innervation: labii superioris alaeque nasi, the levator labii
Oculomotor (III) nerve (superior division) superioris, and the zygomaticus minor.
4 ORBICULARIS OCULI The fibers of the palpebral part sweep across the
upper and lower eyelids anterior to the orbital
Muscle has three parts: septum to form the lateral palpebral raphe. The
ciliary bundle is composed of a small group of
fibers behind the eyelashes.
The lacrimal part fibers lying behind the lacrimal
sac (in the medial corner of the eye) divide into
upper and lower slips that insert into the superior
and inferior tarsi of the eyelids and the lateral
palpebral raphe.
Function:
The orbicularis oculi is the sphincter of the eye.
Orbital part: While closing the eye is mostly lowering
of the upper lid, the lower lid also rises; both lids
are under voluntary control and can work with
greater force, as in winking.
Palpebral part: Closes lids in blinking (protective
reflex) and for sleep (voluntary).
Lacrimal part: Draws the eyelids and lacrimal canals
medially, compressing them against the globe of
the eye to receive tears. Also compresses lacrimal
sac during blinking.
Chapter 9 / Ready Reference Anatomy 3 6 1
Part 3. Skeletal Muscles of the Human Body
Entire muscle contraction draws skin of forehead, the upper eyelid. In addition, there are superior and
temple, and cheek toward the medial angle of inferior tarsal muscles in the upper and lower eyelids;
the eye, tightly closing the eye and displacing the superior is related to the levator palpebrae supe-
the lids medially. T h e folds formed by this ac- rior, while the inferior works with the rectus inferior
tion in later life form "crow's feet." T h e mus- and inferior oblique. The orbicularis oculi also is an
cles around the eye are important because they extraocular muscle, but it is described with the facial
cause blinking, which keeps the eye lubricated muscles.
and prevents dehydration of the conjunctiva.
The muscle also bunches up to protect the eye 6-9 THE FOUR RECTI (Figure 9-1)
from excessive light.
Rectus superior, inferior, medialis, and lateralis
Innervation:
Facial (VII) nerve (temporal and zygomatic Origin:
branches) At the back of the eye, the tendons of the four
recti are attached to a common annular tendon.
5 CORRUGATOR SUPERCILII This tendon rings the superior, medial, and in-
ferior margins of the optic foramen and at-
Origin: taches to the sphenoid bone (greater wing). It
also adheres to the sheath of the optic nerve.
Frontal bone (superciliary arch, medial end) The attachments of the four recti circle the
tendon on its medial, superior, and inferior
Insertion: margins. The ring around the optic nerve is
Skin (deep surface) of eyebrow over middle of completed by a lower fibrous extension (tendon
orbital arch of Zinn), which is the origin of the rectus inferior,
part of the rectus medialis, and the lower head of
Description: origin of the rectus lateralis. An upper fibrous
Fibers of this small muscle lie at the medial end of expansion yields the rectus superior, part of the
each eyebrow, deep to the occipitofrontalis and rectus medialis, and the upper head of the rectus
orbicularis oculi muscles with which it often lateralis.
blends.
Insertion:
Function: Each of the recti passes anteriorly in the position
Draws eyebrows down and medially, producing indicated by its name and inserts via a tendinous
vertical wrinkles of the forehead between the expansion into the sclera a short distance behind
eyes (frowning). This action also shields the eyes the cornea.
from bright sun.
Description:
Innervation: From their common origin around the margins of
Facial (VII) nerve (temporal branch) the optic canal, these straplike muscles become
wider as they pass anteriorly to insert on differ-
OCULAR MUSCLES ent points on the sclera (see Figure 9-1) The
rectus superior is the smallest and thinnest and
6 Rectus superior inserts on the superoanterior sclera under the
orbital roof. The inferior muscle inserts on the
7 Rectus inferior inferoanterior sclera just above the orbital floor.
The rectus medialis is the broadest of the recti
8 Rectus medialis and inserts on the medial scleral wall well in
front of the equator. The rectus lateralis, the
9 Rectus lateralis longest of the recti, courses around the lateral
side of the eyeball to insert well forward of the
10 Obliquus superior equator.
11 Obliquus inferior Function:
The ocular muscles rotate the eyeball in directions
The Extraocular Muscles that depend on the geometry of their relation-
ships and that can be altered by the eye move-
There are seven extraocular muscles of the eye: the ments themselves. Eye movements also are
four recti, the two obliquii, and the levator palpe- accompanied by head motions, which assist with
brae. The recti with the obliquii can move the eye- the incredibly complex varieties of stereoscopic
ball in infinite directions, while the levator can raise vision.
3 6 2 Chapter 9 / Ready Reference Anatomy
Part 3. Skeletal Muscles of the Human Body
FIGURE 9-1 The four recti, lateral view.
The ocular muscles are not subject to direct study Inferior oblique paralysis: Eyeball is deviated
or routine assessment. It is essential to know that downward and slightly medially; it cannot be
a change in the tension of one of the muscles moved upward when in abduction.
alters the length-tension relationships of all six
ocular muscles. It is likely that all six muscles are Superior oblique paralysis: H e r e there may be little
continuously involved, and consideration of each deviation of the eyeball but downward motion is
in isolation is not a functional exercise. The limited when the eye is adducted. There is no
functional relationship between the four recti and movement toward the midline of the face when
the two obliquui may be considered as two looking downward in abduction (intorsion).
differing synergies.
Innervation:
The rectus superior, inferior, and medialis act
together as adductors or convergence muscles. Oculomotor (III) nerve: Rectus superior (superior
division of I I I ) , inferior, and medialis, and obliquus
The lateral rectus together with the two obliquui act inferior (inferior division of III)
as muscles of abduction or divergence.
Abducent (VI) nerve: Rectus lateralis
Convergence generally is associated with elevation of Trochlear (IV) nerve: Obliquus superior
the visual axis, and divergence with lowering of
the visual axis. 10 OBLIQUUS SUPERIOR OCULI
Neurologists regularly test the ocular muscles when Origin:
there is an isolated paralysis, which gives greater
insight into their functions.9 Sphenoid bone (superior and medial to optic
canal)
Superior rectus paralysis: Eye turns down and slightly
outward. Upward motion is limited. Rectus superior (tendon)
Medial rectus paralysis: Eyeball turns laterally and Insertion:
cannot deviate medially.
Frontal bone (via a round tendon that inserts through
Inferior rectus paralysis: Eyeball deviates upward and a pulley [a cartilaginous ring called the trochlea]
somewhat laterally. It cannot be moved downward that inserts in the trochlear fovea)
and the eye is abducted.
Sclera (behind the equator on the superolateral
Lateral rectus paralysis: T h e eyeball is turned medially surface)
and cannot be abducted.
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Part 3. Skeletal Muscles of the Human Body
on the sclera beneath that muscle (see Figures
9-1 and 9 - 2 ) .
Function:
See under Obliquus superior oculi (No. 10)
Innervation:
Oculomotor (III) nerve (inferior division)
MUSCLES OF THE NOSE
FIGURE 9-2 The oblique extraocular muscles. 12 Procerus
13 Nasalis
14 Depressor septi
Description: 12 PROCERUS
The superior oblique lies superomedially in the or-
bit (Figure 9 - 2 ) . It passes forward, ending in the Origin:
round tendon that loops through the trochlear Nasal bone (dorsum of nose, lower part)
pulley, which is attached to the trochlear fovea. Nasal cartilage (lateral, upper part)
It then turns abruptly posterolaterally and
passes to the sclera to end between the Insertion:
rectus superior and the rectus lateralis. Skin over lower part of forehead between eyebrows
Joins occipitofrontalis
Function:
The superior oblique acts on the eye from above, Description:
whereas the inferior oblique acts on the eye From its origin over bridge of nose it courses straight
directly below; the superior oblique elevates the upward to blend with frontalis.
posterior aspect of the eyeball, and the inferior
oblique depresses it. The superior oblique, Function:
therefore, rotates the visual axis downward, Produces transverse wrinkles over bridge of nose
whereas the inferior oblique rotates it upward, Draws eyebrows downward
both motions occurring around the transverse
axis. Innervation:
Facial (VII) nerve (buccal branch)
Innervation:
Trochlear (IV) nerve 13 NASALIS
11 OBLIQUUS INFERIOR OCULI Transverse Part (Compressor Nares)
Origin: Origin:
Maxilla (orbital surface, lateral to the lacrimal
groove) Maxilla (above and lateral to incisive fossa)
Insertion: Insertion
Sclera (lateral part) behind the equator of the eye- Aponeurosis over bridge of nose, joining with muscle
ball between the insertions of the rectus in- on opposite side
ferior and rectus lateralis and near, but behind,
the insertion of the superior oblique Alar Part (Dilator Nares)
Description: Origin:
Located near the anterior margin of the floor of Maxilla (above lateral incisor tooth)
the orbit, it passes laterally under the eyeball Alar cartilage
between the rectus inferior and the bony orbit.
It then bends upward on the lateral side of the Insertion:
eyeball, passing under the rectus lateralis to insert Ala nasi
Skin at tip of nose
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Description: 19 Zygomaticus minor
Muscle has two parts that cover the distal and me-
dial surfaces of the nose. Fibers from each side 20 Risorius
rise upward and medially, meeting in a narrow
aponeurosis near the bridge of the nose. 21 Mentalis
Function: 22 Transversus menti
Transverse part: Depresses cartilaginous portion of
nose and draws alae toward septum 23 Depressor anguli oris
Alar part: Dilates nostrils (during breathing it resists
tendency of nares to close from atmospheric 24 Depressor labii inferioris
pressure)
25 Orbicularis oris
Noticeable in anger or labored breathing
26 Buccinator
Innervation:
Facial (VII) nerve (buccal and zygomatic 15 LEVATOR LABII SUPERIORIS
branches)
(Also called quadratus labii superioris)
14 DEPRESSOR SEPTI
Origin:
Origin: Orbit of eye (inferior margin)
Maxilla (above and lateral to incisive fossa, i.e., central Maxilla
incisor) Zygomatic bone
Insertion: Insertion:
Upper lip
Nasal septum (mobile part) and alar cartilage
Description:
Description: Converging from a rather broad place of origin on
Fibers ascend vertically from central maxillary ori- the inferior orbit, the fibers converge and de-
gin. Muscle lies deep to the superior labial mu- scend into the upper lip between the other lev-
cous membrane. It often is considered part of ator muscles and the zygomaticus minor.
the dilator nares (of the nasalis).
Function:
Function: Elevates and protracts upper lip
Draws alae of nose downward (constricting nares) Innervation:
Facial (VII) nerve (buccal branch)
Innervation:
Facial (VII) nerve (buccal and zygomatic 16 LEVATOR LABII SUPERIORIS
branches) ALAEQUE NASI
MUSCLES OF THE MOUTH Origin:
Maxilla (frontal process)
There are four independent quadrants, each of which
has a pars peripheralis that lies along the junction Insertion:
of the red margin of the lip and skin and a pars mar- Ala of nose
ginalis that is found in the red margin of the lip Upper lip
(see Figure 9-3). These two parts are supported by
fibers from the buccinator and depressor anguli oris Description:
(upper lip) and from the buccinator and levator an- Muscle fibers descend obliquely lateral and divide
guli oris (lower lip). These muscles are uniquely de- into two slips: one to the greater alar cartilage
veloped for speech. of the nose and one to blend with the levator labii
superioris and orbicularis oris (then to the
15 Levator labii superioris modiolus).
16 Levator labii superioris alaeque nasi Function:
Dilates nostrils
17 Levator anguli oris Elevates upper lip
18 Zygomaticus major Innervation:
Facial (VII) nerve (buccal branch)
Chapter 9 / Ready Reference Anatomy 3 6 5
Commentary on Facial Muscles
The muscles of the face are different from most skeletal denervated or in the presence of the atrophic processes
muscles in the body because they are cutaneous muscles associated with aging. There are wide differences in these
located in the deep layers of the skin and frequently have muscles among individuals and among racial groups, and
no bony attachments. All of them (scalp, eyelids, nose, lips, to deal with such variations craniofacial and plastic
cheeks, mouth, and auricle) give rise to "expressions" and surgeons often classify the facial muscles differently
convey "thought," the most visible of the body language (e.g., in single vs. multiple heads) from the system presented
systems (Figure 9 - 3 ) . here.
The orbital muscles of the mouth are important for Continuous skin tension also results in the gaping wounds
speech, drinking, and ingestion of solid f o o d s . 1 0 , 1 2 Although that occur with facial lacerations, and surgeons take great
the buccinator is described in this section, it is not a muscle care to understand the planes of the muscles to minimize
of expression but does serve an important role in regulating scarring in the repair of such wounds.
the position of, and action on, food in the mouth.
T h e facial muscles all arise from the mesoderm of the
These muscles are continuously tonic to provide the second branchial (hyoid) arch. T h e muscles lie in all parts
facial skin with tension; the skin becomes baggy or flabby of the face and head but retain their innervation by the facial
(resulting in, e.g., "crow's feet" or "wattles") when it is (VII) nerve.
FIGURE 9-3 Muscles of the head and neck (superficial lateral view), including cicumorbital, buccolabial,
nasal, epicranial, masticatory, and cervical groups. The articular muscles are omitted. Risorius, a variable
muscle, here has two fasciculi, of which the lower one is unlabeled. The nature of the modiolus and the
modiolar muscles and their cooperation in facial movement is described in the text. The laminae of the direct
labial tractors to both upper and lower lips have been transected to reveal the orbicularis oris underneath.
(From Williams PL et al (eds). Gray's Anatomy, 38th ed. London: Churchill Livingstone, 1 9 9 9 . )
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Part 3. Skeletal Muscles of the Human Body
1 7 LEVATOR ANGULI ORIS Function:
Muscle of facial expression (as in sneering, expressions
Origin: of contempt, and smiling)
Maxilla (canine fossa) Elevates and curls upper lip, exposing the maxil-
lary teeth
Insertion: Deepens nasolabial furrow
Modiolus
Innervation:
Dermal attachment at angle of mouth Facial (VII) nerve (buccal branch)
Description: 20 RISORIUS
Muscle descends from maxilla, inferolateral to orbit,
down to modiolus. It lies partially under the Origin:
zygomaticus minor. Masseteric fascia
Function: Insertion:
Raises angle of mouth and by so doing displays teeth Modiolus10,12
in smiling
Contributes to nasolabial furrow (from side of nose Description:
to corner of upper lip); deepens in sadness and This muscle is so highly variable that even when pres-
aging ent it is possibly wrong to classify it as a sepa-
rate muscle. When present, it passes forward almost
Innervation: horizontally. It may vary from a few fibers to a
Facial (VII) nerve (buccal branch) wide, thin, superficial, fan-shaped sheet. It is often
considered the muscle of laughing, but this is
18 ZYGOMATICUS MAJOR equally true of other modiolar muscles.
Origin: Function:
Zygomatic bone (lateral) When present, retracts angle of mouth
Insertion: Innervation:
Modiolus10-12 Facial (VII) nerve (buccal branch)
Description: 21 MENTALIS
Descends obliquely lateral to blend with other
modiolar muscles. A small and variable group Origin:
of superficial fascicles called the malaris are Mandible (incisive fossa)
considered part of this muscle.
Insertion:
Function: Skin over chin
Draws angle of mouth lateral and upward (as in
laughing) Description:
Descends medially from its origin just lateral to
Innervation: labial frenulum to center of skin of chin
Facial (VII) nerve (buccal branch)
Function:
19 ZYGOMATICUS MINOR Wrinkles skin over chin
Protrudes and raises lower lip (as in sulking or
Origin: drinking)
Zygomatic bone (malar surface) medial to origin
of zygomaticus major Innervation:
Facial (VII) nerve (marginal mandibular branch)
Insertion:
Upper lip; blends with levator labii superioris 22 TRANSVERSUS MENTI
Modiolus10-12
Origin:
Description: Skin of the chin (laterally)
Descends initially with zygomaticus major, and then
moves medially on top of levator labii superioris, Insertion:
with which it blends. Skin of the chin
Blends with its contralateral muscle
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Part 3. Skeletal Muscles of the Human Body
Description: 25 ORBICULARIS ORIS
As frequently absent as it is present. Very small muscle
traverses chin interiorly and therefore is called the Origin:
mental sling. Often continuous with depressor No fascial attachments except the modiolus. This
anguli oris. is a composite muscle with contributions from
other muscles of the mouth, which form a
Function: complex sphincterlike structure, but it is not a
Depresses angle of mouth; supports skin of chin true sphincter. Via its incisive components, the
muscle attaches to the maxilla (incisivus labii
Innervation: superioris) and mandible (incisivus labii inferi-
Facial (VII) nerve (marginal mandibular branch) oris).
23 DEPRESSOR ANGULI ORIS Insertion:
Modiolus
Origin:
Mandible (mental tubercle and oblique line) Labial connective tissue
Insertion: Description2:
Modiolus
This muscle is not a complete ellipse of muscle
Description: surrounding the mouth. The fibers actually
Ascends in a curve from its broad origin below form four separate functional quadrants on each
tubercle of mandible to a narrow fasciculus side that provide great diversity of oral move-
into modiolus. Often continuous below with ments. There is overlapping function among
platysma. the quadrants (upper, lower, left, and right).
The muscle is connected with the maxillae and
Function: angle of septum of the nose by lateral and medial accessory
Depresses lower lip and pulls down muscles.
mouth
Facial expression muscle (as in sadness) The incisivus labii superioris is a lateral accessory
muscle of the upper lip within the orbicularis
Innervation: oris, and there is a similar accessory muscle, the
Facial (VII) nerve (marginal mandibular branch) incisivus labii inferioris, for the lower lip. These
muscles have bony attachments to the floor of
24 DEPRESSOR LABII INFERIORS the maxillary incisive (superior) fossa and the
mandibular incisive (inferior) fossa. They arch
(Also called quadratus labii inferioris) laterally between the orbicularis fibers on the
respective lip and, after passing the buccal an-
Origin: gle, insert into the modiolus. The modiolus
Mandible (oblique line between symphysis and acts as a force-transmission system to the lips
mental foramen) from muscles attached to it.
Insertion: The orbicularis oris has another accessory muscle,
Skin and mucosa of lower lip the nasolabialis, that lies medially and connects
Modiolus the upper lip to the nasal septum. (The interval
between the contralateral nasolabialis
Description: corresponds to the philtrum, the depression on
Passes upward and medially from a broad origin; the upper lip beneath the nasal septum.)
then narrows and blends with orbicularis oris
and depressor labii inferioris of opposite side. Function: sucking, drink-
Closes lips
Function: Protrudes lips
Draws lower lip down and laterally Holds lips tight against teeth
Facial expression muscle (sorrow, sadness) Shapes lips for whistling, kissing,
ing, etc.
Innervation:
Facial (VII) nerve (marginal mandibular branch) Alters shape of lips for speech and musical sounds
Innervation:
Facial (VII) nerve (buccal and marginal mandibular
branches)
This innervation is of interest because when one
facial nerve is injured distal to the stylomastoid
foramen, only half of the orbicularis oris mus-
cle is paralyzed. When this occurs, as in Bell's
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Part 3. Skeletal Muscles of the Human Body
palsy, the mouth droops and may be drawn to the Auricularis posterior
opposite side.
Origin:
26 BUCCINATOR Temporal bone (mastoid process) via a short
aponeurosis
Origin:
Maxilla and mandible (external surfaces of alveolar Insertion:
processes opposite molars) Auricle (cranial surface, concha)
Pterygomandibular raphe
Function (all):
Insertion: Limited function in humans except at parties! The
Modiolus anterior muscle elevates the auricle and moves
it forward; the superior muscle elevates the auricle
Submucosa of cheek and lips slightly, and the posterior draws it back. Auditory
stimuli may evoke minor responses from these
Description: muscles.
The principal muscle of the cheek is classified as a
facial muscle (because of its innervation) despite Innervation:
its role in mastication. T h e buccinator forms Facial (VII) nerve (temporal branch to anterior and
the lateral wall of the oral cavity, lying deep to superior auriculares; posterior auricular branch to
the other facial muscles and filling the gap be- posterior auricular muscle)
tween the maxilla and the mandible.
MUSCLES OF JAW AND MASTICATION
Function:
Compresses cheek against the teeth 28 Masseter
Expels air when cheeks are distended (in blowing) 29 Temporalis
Acts in mastication to control passage of food 30 Lateral pterygoid
31 Medial pterygoid
Innervation:
Facial (VII) nerve (buccal branch)
EXTRINSIC MUSCLES OF THE EAR 28 MASSETER
Intrinsic muscles of the ear (6 in number) connect one Has three parts
part of the auricle to another and are not accessible or
useful for manual testing. The three extrinsic muscles Superficial part:
connect the auricle with the skull and scalp.
Origin:
27 THE AURICULARES (Three Muscles) Maxilla (zygomatic process via an aponeurosis)
Zygomatic bone (maxillary process and inferior
Auricularis anterior border of arch)
Origin: Insertion:
Anterior fascia in temporal area (lateral edge of Mandible (ramus: angle and lower half of lateral
epicranial aponeurosis) surface)
Insertion: Intermediate part:
Spine of cartilaginous helix of ear Origin:
Zygomatic arch (inner surface of anterior 2/3)
Auricularis Superior
Insertion:
Origin: Mandible (ramus, central part)
Temporal fascia
Deep part:
Insertion:
Auricle (cranial surface) Origin:
Zygomatic arch (posterior 1/3 continuous with
intermediate part)
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Part 3. Skeletal Muscles of the Human Body
Insertion: Origin:
Mandible (ramus [superior half] and lateral coronoid Superior head: S p h e n o i d b o n e (greater wing,
process)
infratemporal crest and surface)
Description: Inferior head: Sphenoid b o n e (lateral pterygoid plate,
A thick muscle connecting the upper and lower
jaws and consisting of three layers that blend lateral surface)
anteriorly. The superficial layer descends back-
ward to the angle of the mandible and the Insertion: capsule
lower mandibular ramus. (The middle and deep Mandible (condylar neck, pterygoid fossa)
layers compose the deep part cited in Nomina Temporomandibular joint ( T M J ) (articular
Anatomical) T h e muscle is easily palpable and and disk)
lies under the parotid gland posteriorly; the
anterior margin overlies the buccinator. Description:
Function: of the teeth in A short, thick muscle with two heads that runs
Elevates the mandible (occlusion posterolaterally to the mandibular condyle,
mastication) neck, and disk of the T M J . The fibers of the
Up-and-down biting motion upper head are directed downward and laterally,
while those of the lower head course horizon-
tally. The muscle lies under the mandibular
ramus.
Innervation: Function:
Trigeminal (V) nerve (mandibular division, masseteric Protracts mandibular condyle and disk of T M J
branches) forward while the mandibular head rotates on disk
(participates in opening of mouth).
29 TEMPORALIS
The lateral pterygoid, acting with the elevators of
Origin: the mandible, protrudes the jaw, causing maloc-
Temporal bone (all of temporal fossa) clusion of the teeth (i.e., the lower teeth project
Temporal fascia (deep surface) in front of the upper teeth).
Insertion: When the lateral and medial pterygoids on the
Mandible (coronoid process, medial surface, apex, same side act jointly, the mandible and the
and anterior border; anterior border of ramus jaw (chin) rotate to the opposite side (chewing
almost to third molar) motion).
Description: Assists mouth closure: condyle retracts as muscle
A broad muscle that radiates like a fan on the side lengthens to assist masseter and temporalis.
of the head from most of the temporal fossa,
converging downward to the coronoid process of Innervation:
the mandible. The descending fibers converge into Trigeminal (V) nerve (mandibular division, nerve to
a tendon that passes between the zygomatic arch lateral pterygoid)
and the cranial wall. The more anterior fibers
descend vertically, but the more posterior the fibers 31 MEDIAL PTERYGOID
the more oblicjue their course until the most
posterior fibers are almost horizontal. Difficult to Origin: pyramidal
palpate unless muscle is contracting as in clenching Sphenoid bone (lateral pterygoid plate)
of teeth. Palatine bone (grooved surface of
process)
Maxilla (tuberosity)
Palatine bone (tubercle)
Function: Insertion:
Elevates mandible to close mouth and approximate Mandible medial surface of ramus via a strong
teeth (biting motion) tendon, reaching as high as mandibular
Retracts mandible (posterior fibers) foramen
Participates in lateral grinding motions
Innervation: (mandibular division, deep Description:
Trigeminal (V) nerve
temporal branch) This short, thick muscle occupies the position on the
inner side of the mandibular ramus, whereas the
30 LATERAL PTERYGOID masseter occupies the outer position. The medial
pterygoid is separated by the lateral pterygoid from
Has t w o heads the mandibular ramus. The deep fibers arise from
the palatine bone; the more superficial fibers arise
from the maxilla and lie superficial to the lateral
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Part 3. Skeletal Muscles of the Human Body
pterygoid. The fibers descend posterolaterally to fibers run posteriorly and join the middle
the mandibular ramus. constrictor of the pharynx; the superior fibers run
upward to insert on the whole length
Function: of the underside of the tongue. The muscles of
Elevates mandible to close jaws (biting). the two sides are blended anteriorly and sepa-
Protrudes mandible (with lateral pterygoid). rated posteriorly by the medial lingual septum.
Unilaterally, the medial and lateral pterygoids to-
gether rotate the mandible forward and to Function:
the opposite side. This alternating motion is Protraction of tongue (tip protrudes beyond mouth)
chewing. Depression of central part of tongue
The medial pterygoid and masseter are situated to
form a sling that suspends the mandible. This Innervation:
sling is a functional articulation in which the Hypoglossal (XII) nerve, muscular branch
T M J acts as a guide. As the mouth opens and
closes, the mandible moves on a center of rota- 33 HYOGLOSSUS
tion established by the sling and the spheno-
mandibular ligament. Origin:
Hyoid bone (side of body and whole length of greater
Innervation: horn)
Trigeminal (V) nerve (mandibular division, nerve
to medial pterygoid) Insertion:
Side of tongue
MUSCLES OF THE TONGUE
Description:
Extrinsic Tongue Muscles Thin, quadrilateral muscle whose fibers run almost
vertically
32 Genioglossus
Function:
33 Hyoglossus Depression and retraction of tongue
34 Chondroglossus Innervation:
Hypoglossal (XII) nerve, muscular branch
35 Styloglossus
34 CHONDROGLOSSUS
36 Palatoglossus
Origin:
32 GENIOGLOSSUS Hyoid bone (lesser horn, medial side)
Origin: Insertion:
Mandible (symphysis menti on inner surface of
superior mental spine) Blends with intrinsic muscles on side of tongue
Insertion: Description: is
Hyoid bone via a thin aponeurosis
Middle pharyngeal constrictor muscle A very small muscle (about 2 cm long) that
Undersurface of tongue, whole length mingling sometimes considered part of the hyoglossus
with the intrinsic musculature of tongue
Function:
Description: Assists in tongue depression
The tongue is separated into lateral halves by the
lingual septum, which extends along its full length Innervation:
and inserts inferiorly into the hyoid bone. The Hypoglossal (XII) nerve, muscular branch
extrinsics extend outside the tongue.
The genioglossus is a thin, flat muscle that fans out 35 STYLOGLOSSUS
backward from its mandibular origin, running
parallel with and close to the midline. The lower Origin:
fibers run downward to the hyoid; the median Temporal bone (styloid process, apex)
Stylomandibular ligament (styloid end)
Insertion
Muscle divides into two portions before entering side
of tongue
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Courses along side of tongue near dorsal surface to Arises from submucous fibrous layer near epiglottis
blend with intrinsics (longitudinal portion) and from the median lingual septum. Fibers run
anteriorly to the edges of the tongue.
Overlaps hyoglossus and blends with it (oblique
portion) For function and innervation of intrinsics, see Vertical
lingual (No. 4 0 ) .
Description: 38 INFERIOR LONGITUDINAL
Shortest and smallest of extrinsic tongue muscles. Attachments and Description:
The muscle curves down anteriorly and divides Narrow band of fibers close to the inferior lingual
into longitudinal and oblique portions. It lies surface. Extends from the root to the apex of the
between the internal and external carotid arteries. tongue. Some fibers connect to hyoid body. Blends
with styloglossus anteriorly.
Function:
Draws tongue up and backward
Innervation: 39 TRANSVERSE LINGUAL
Hypoglossal (XII) nerve, muscular branch
Attachments and Description:
36 PALATOGLOSSUS Passes laterally across tongue from the median lingual
septum to the edges of the tongue. Blends with
Origin: palatopharyngeus.
Soft palate (anterior surface)
Insertion: 40 VERTICAL LINGUAL
Side of tongue, intermingling with intrinsic muscles
Attachments and Description:
Description: Located only at the anterolateral regions and extends
from the dorsal to the ventral surfaces of the
Technically an extrinsic muscle of the tongue, this tongue.
muscle is functionally closer to the palate mus-
cles. It is a small fasciculus, narrower in the Function of Intrinsics:
middle than at its ends. It passes anteroinferi- These muscles change the shape and contour of
orly and laterally in front of the tonsil to reach the tongue. The longitudinal muscles tend to
the side of the tongue. Along with the mucous shorten it. The superior longitudinal also turns
membrane covering it, the palatoglossus forms the apex and sides upward, making the dorsum
the palatoglossal arch or fold. concave. The inferior longitudinal pulls the
apex and sides downward to make the dorsum
Function: with its opposite convex. The transverse muscle narrows and
Elevates root of tongue cavity from the elongates the tongue. T h e vertical muscle flat
Closes palatoglossal arch (along tens and widens it.
member) to close the oral
oropharynx These almost limitless alterations give the tongue
the incredible versatility and precision necessary
Innervation: for speech and swallowing functions.
Vagus (X) nerve (pharyngeal plexus)
Innervation of Intrinsics:
Intrinsic Tongue Muscles Hypoglossal (XII) nerve
37 Superior longitudinal MUSCLES OF THE PHARYNX
38 Inferior longitudinal
39 Transverse lingual 41 Inferior pharyngeal constrictor
40 Vertical lingual 42 Middle pharyngeal constrictor
43 Superior pharyngeal constrictor
37 SUPERIOR LONGITUDINAL 44 Stylopharyngeus
45 Salpingopharyngeus
Attachments and Description: 49 Palatopharyngeus (see Muscles of the Palate)
Oblique and longitudinal fibers run immediately
under the mucous membrane on dorsum of
tongue.
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Part 3. Skeletal Muscles of the Human Body
41 INFERIOR PHARYNGEAL Innervation:
CONSTRICTOR Pharyngeal plexus formed by components of vagus
(X), accessory (XI), and glossopharyngeal (IX)
Origin: nerves
Cricoid cartilage (sides)
Thyroid cartilage (oblique line on the side as well as 43 SUPERIOR PHARYNGEAL
from inferior cornu) CONSTRICTOR
Insertion: Origin (in four parts):
Pharynx (posterior median fibrous raphe, along with Sphenoid bone (medial pterygoid plate and its
its contralateral partner) hamulus [pterygopharyngeal part])
Pterygomandibular raphe (buccopharyngeal part)
Description: Mandible (mylohyoid line [mylopharyngeal part])
The thickest and largest of the pharyngeal con- Side of tongue (glossopharyngeal part)
strictors, the muscle has two parts: the
cricopharyngeus and the thyropharyngeus. Insertion:
Both parts spread to join the muscle of the op- Median pharyngeal fibrous raphe
posite side at the fibrous median raphe. The lowest Occipital bone (pharyngeal tubercle on basilar
fibers run horizontally and circle the narrowest part)
part of the pharynx. The other fibers course
obliquely upward to overlap the middle Description:
constrictor. The smallest of the constrictors, the fibers of this
During swallowing the cricopharyngeus acts like a muscle curve posteriorly and are elongated by
sphincter; the thyropharyngeus uses peristaltic an aponeurosis to reach the occiput. The attach-
action to propel food downward. ments of this muscle are differentiated as
pterygopharyngeal, buccopharyngeal, mylo-
Function: pharyngeal, and glossopharyngeal.
During swallowing all constrictors act as general The interval between the superior border of this
sphincters and assist in peristaltic action. muscle and the base of the skull is closed by the
pharyngobasilar fascia known as the sinus of
Innervation: Morgagni.
Pharyngeal plexus formed by components of vagus A small band of muscle blends with the superior
(X), accessory (XI), glossopharyngeal (IX), and constrictor from the upper surface of the palatine
external laryngeal nerves aponeurosis and is called the palatopharyngeal
sphincter. This band is visible when the soft palate
42 MIDDLE PHARYNGEAL is elevated; often it is hypertrophied in individuals
CONSTRICTOR with cleft palate.
Origin (in two parts): Function:
Hyoid bone (whole length of superior border of lesser Acts as a sphincter and has peristaltic functions in
cornu and stylohyoid ligament [chon- swallowing
dropharyngeal part])
Hyoid bone (whole border of greater cornu Innervation:
[ceratopharyngeal part]) Pharyngeal plexus (from Vagus and Accessory)
Stylohyoid ligament
Insertion: 44 STYLOPHARYNGEUS
Pharynx (posterior median fibrous raphe) Origin:
Temporal bone (styloid process, medial side of
Description: base)
From their origin the fibers fan out in three direc-
tions: the lower fibers descend to lie under the Insertion:
inferior constrictor, the medial fibers pass trans- Blends with pharyngeal constrictors and palato-
versely, and the superior fibers ascend to over- pharyngeus
lap the superior constrictor. At its insertion it Thyroid cartilage (posterior border)
joins with the muscle from the opposite side.
Description:
Function: A long, thin muscle that passes downward along
Serves as a sphincter and acts during peristaltic the side of the pharynx and between the superior
functions in deglutition
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Part 3. Skeletal Muscles of the Human Body
and middle constrictors to spread out beneath the pharyngeus. They form a sling for the palatine
mucous membrane aponeurosis.
Function: Function:
Elevation of upper lateral pharyngeal wall in Elevates soft palate
swallowing Retracts soft palate
Innervation: Innervation
Glossopharyngeal (IX) nerve Pharyngeal plexus
45 SALPINGOPHARYNGEUS 47 TENSOR VELI PALATINI
Origin: (Tensor Palati)
Auditory (pharyngotympanic) tube (inferior aspect of
cartilage near orifice) Origin:
Sphenoid bone (pterygoid process, scaphoid fossa)
Insertion: Auditory (pharyngotympanic) tube cartilage
Blends with palatopharyngeus Sphenoid spine (medial part)
Description: Insertion:
Small muscle whose fibers pass downward, lateral to Palatine aponeurosis
the uvula, to blend with fibers of the Palatine bone (horizontal plate)
palatopharyngeus
Description1 :
Function: This small thin muscle lies lateral to the levator
Elevates pharynx to move a bolus of food veli palatini and the auditory tube. It descends
vertically between the medial pterygoid plate
Innervation: and the medial pterygoid muscle, converging into
Pharyngeal plexus a delicate tendon, which turns medially around
the pterygoid hamulus.
MUSCLES OF THE PALATE
Function:
46 Levator veli palatini Draws soft palate to one side (unilateral)
47 Tensor veli palatini Tightens soft palate, depressing it and flattening its
48 Musculus uvulae arch (with its contralateral counterpart)
49 Palatopharyngeus Opens auditory tube in yawning and swallowing and
36 Palatoglossus (see Muscles of the Tongue) eases any buildup of air pressure between the
nasopharynx and middle ear
46 LEVATOR VELI PALATINI
Innervation:
(Levator Palati) Trigeminal (V) nerve (to medial pterygoid)13
Origin: 48 MUSCULUS UVULAE
Temporal bone (inferior surface of petrous bone)
Tympanic fascia (Azygos Uvulae)
Auditory (pharyngotympanic) tube cartilage Origin:
Palatine bones (posterior nasal spine)
Insertion: Palatine aponeurosis
Palatine aponeurosis (upper surface, where it blends
with opposite muscle at the midline) Insertion:
Uvula (connective tissue and mucous membrane)
Description:
Fibers of this small muscle run downward and me- Description:
dially from the petrous temporal bone to pass A bilateral muscle, its fibers descend into the
above the margin of the superior pharyngeal uvular mucosa.
constrictor and anterior to the salpingo-
Function: palato-
Elevates and retracts uvula to assist with
pharyngeal closure
Seals nasopharynx (along with levators)
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Part 3. Skeletal Muscles of the Human Body
Innervation: 55 Thyroarytenoid
Pharyngeal plexus (X and XI) Vocalis
Thyroepiglotticus
49 PALATOPHARYNGEUS
50 CRICOTHYROID
(Pharyngopalatinus)
Origin:
Origin (by two fasciculi): Cricoid cartilage (front and lateral)
Anterior Fasciculus: Insertion:
Soft palate (palatine aponeurosis) Thyroid cartilage (inferior cornu)
Hard palate (posterior border) Thyroid lamina
Posterior Fasciculus: Description:
Pharyngeal aspect of soft palate (palatine aponeu- The fibers of this paired muscle are arranged in
rosis) two groups: a lower oblique group (pars obliqua),
which slants posterolaterally to the inferior cornu,
Insertion: and a superior group (pars recta or vertical fibers),
Thyroid cartilage (posterior border) which ascends backward to the lamina.
Side of pharynx on an aponeurosis
Function:
Description: Regulates tension of vocal folds
Along with its overlying mucosa, it forms the Stretches vocal ligaments by raising the cricoid
palatopharyngeal arch. It arises by two fasciculi arch, thus increasing tension in the vocal folds
separated by the levator veli palatini, all of
which join in the midline with their opposite Innervation:
muscles. The two muscles unite and are joined Vagus (X) nerve (external laryngeal branch)
by the salpingopharyngeus to descend behind
the tonsils. The muscle forms an incomplete 51 POSTERIOR CRICOARYTENOID
longitudinal wall on the internal surface of the
pharynx. Origin: on
Cricoid cartilage lamina (broad depression
Function: corresponding half of posterior surface)
Elevates pharynx and pulls it forward, thus short-
ening it during swallowing. The muscles also Insertion:
narrow the palatopharyngeal arches (fauces). Arytenoid cartilage on same side (back of muscular
Depresses soft palate. process)
Innervation: Description:
Pharyngeal plexus (X and XI) The fibers of this paired muscle pass cranially and
laterally to converge on the back of the arytenoid
36 PALATOGLOSSUS cartilage on the same side. The lowest fibers are
nearly vertical and become oblique and finally
See Muscles of the Tongue. almost transverse at the superior border.
MUSCLES OF THE LARYNX Function:
Regulates tension of vocal folds
(Intrinsics) Opens glottis by rotating arytenoid cartilages laterally
and separating (abducting) the vocal folds
These muscles are confined to the larynx: Retracts arytenoid cartilages, thereby helping to tense
50 Cricothyroid the vocal folds
51 Posterior cricoarytenoid
52 Lateral cricoarytenoid Innervation:
53 Transverse arytenoid Vagus (X) nerve (recurrent laryngeal nerve)
54 Oblique arytenoid
52 LATERAL CRICOARYTENOID
Origin:
Cricoid cartilage (cranial border of arch)
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Insertion: 55 THYROARYTENOID
Arytenoid cartilage on same side (front of muscular
process) Origin:
Thyroid cartilage (caudal half of angle)
Description: Middle cricothyroid ligament
Fibers run obliquely upward and backward. The
muscle is paired. Insertion:
Arytenoid cartilage (base and anterior surface)
Function cartilages Vocal process (lateral surface)
Closes glottis by rotating arytenoid the vocal
medially, approximating (adducting) Description:
folds for speech T h e paired muscles lie lateral to the vocal fold,
ascending posterolaterally. Many fibers are carried
Innervation to the aryepiglottic fold.
Vagus (X) nerve (recurrent laryngeal branch) The lower and deeper fibers, which lie medially,
appear to be differentiated as a band inserted into
53 TRANSVERSE ARYTENOID the vocal process of the arytenoid cartilage. This
band frequently is called the vocalis muscle. It is
Attachments and Description: adherent to the vocal ligament, to which it is lateral
A single muscle (i.e., unpaired) that crosses trans- and parallel.
versely between the two arytenoid cartilages. Often Other fibers of this muscle continue as the
considered a branch of an arytenoid muscle. It thyroepiglotticus muscle and insert into the
attaches to the back of the muscular process and epiglottic margin; other fibers that swing along
the adjacent lateral borders of both arytenoid the wall of the sinus to the side of the epiglottis
cartilages. are termed the superior thyroarytenoid and relax
the vocal folds.
Function:
Approximates (adducts) the arytenoid cartilages, Function:
closing the glottis Regulates tension of vocal folds.
Draws arytenoid cartilages toward thyroid cartilage,
Innervation: thus shortening and relaxing vocal ligaments.
Vagus (X) nerve (recurrent laryngeal nerve) Rotates the arytenoid cartilages medially to
approximate vocal folds.
54 OBLIQUE ARYTENOID The vocalis relaxes the posterior vocal folds while the
anterior folds remain tense, thus raising the pitch
Origin: of the voice.
T h e thyroepiglotticus widens the laryngeal inlet via
Arytenoid cartilage (back of muscular process) action on the aryepiglottic folds.
The superior thyroarytenoids relax the vocal cords
Insertion: and aid in closure of the glottis.
Arytenoid cartilage on opposite side (apex) Innervation:
Vagus (X) nerve (recurrent laryngeal nerve)
Description:
A pair of muscles lying superficial to the MUSCLES OF THE NECK AND
transverse arytenoid. Arrayed as two fasciculi SUBOCCIPITAL TRIANGLE
that cross on the posterior midline. Often
considered part of an arytenoid muscle. Fibers that Capital Extensor Muscles
continue laterally around the apex of the
arytenoid are sometimes termed the aryepiglottic This group of eight muscles consists of suboccipital
muscle. muscles extending between the atlas, axis, and skull and
large overlapping muscles from the 6th thoracic verte-
Function: bra to the 3rd cervical vertebra and rising to the skull.
Acts as a sphincter for the laryngeal inlet (by ad-
ducting the aryepiglottic folds and approximating 56 Rectus capitis posterior major
the arytenoid cartilages)
57 Rectus capitis posterior minor
Innervation:
Vagus (X) nerve (recurrent laryngeal nerve)
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58 Obliquus capitis superior Innervation:
C1 spinal nerve (suboccipital nerve, dorsal rami)
59 Obliquus capitis inferior
58 OBLIQUUS CAPITIS SUPERIOR
60 Longissimus capitis
Origin:
61 Splenius capitis Atlas (transverse process, superior surface), where it
joins insertion of obliquus capitis inferior
62 Semispinalis capitis
Insertion:
63 Spinalis capitis Occiput (between superior and inferior nuchal lines;
lies lateral to semispinalis capitis)
The capital extensor muscles control the head as a
separate entity from the cervical spine.14 The muscles Description:
are paired. Starts as a narrow muscle and then widens as it rises
upward and medially. It is more a postural muscle
83 Sternocleidomastoid (posterior) (see Cervical than a muscle for major motion.
Spine Flexors)
Function:
124 Trapezius (upper) (see page 3 9 7 ) Capital extension of head on atlas (muscle on both
sides)
56 RECTUS CAPITIS POSTERIOR Lateral bending to same side (muscle on that side)
MAJOR
Innervation:
Origin: C1 spinal nerve (suboccipital nerve, dorsal rami)
Axis (spinous process)
59 OBLIQUUS CAPITIS INFERIOR
Insertion:
Occiput (lateral part of inferior nuchal line; surface Origin:
just inferior to nuchal line) Axis (apex of spinous process)
Description: Insertion:
Starts as a small tendon and broadens as it rises Atlas (transverse process, inferior and dorsal
upward and laterally (review suboccipital triangle surface)
in any anatomy text)
Description:
Function: Passes laterally and slightly upward. This is the larger
Capital extension of the two obliquui.
Rotation of head to same side
Lateral bending of head to same side Function:
Rotation of head to same side
Innervation: Lateral bending (muscle on that side)
CI spinal nerve (suboccipital nerve, dorsal rami)
Innervation:
57 RECTUS CAPITIS POSTERIOR C1 spinal nerve (suboccipital nerve, dorsal rami)
MINOR
60 LONGISSIMUS CAPITIS
Origin:
Origin:
Atlas (tubercle on posterior arch) T 1 - T 5 vertebrae (transverse processes)
C4-C7 vertebrae (articular processes)
Insertion:
Occiput (medial portion of inferior nuchal line; Insertion:
surface between inferior nuchal line and foramen
magnum) Temporal bone (mastoid process [posteriormargin])
Description: Description:
Begins as a narrow tendon that broadens into a wide A muscle with several tendons lying under the
band of muscle as it ascends splenius cervicis. Sweeps upward and laterally
Function:
Capital extension
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Part 3. Skeletal Muscles of the Human Body
and is considered a continuation of the Innervation:
sacrospinal. C 2 - T 1 spinal nerves (dorsal rami); greater occipital
nerve (variable)
Function: 63 SPINALIS CAPITIS
Capital extension
Lateral bending and rotation of head to same Origin:
side C 5 - C 7 and T 1 - T 3
processes)
vertebrae (variable) (spinous
Innervation: nerves with variations (dorsal
C3-C8 cervical
rami) Insertion:
Occiput (between superior and inferior nuchal
61 SPLENIUS CAPITIS lines)
Origin: with Description:
Ligamentum nuchae at C3-C7 vertebrae The smallest and thinnest of the erector spinae,
C7-T4 vertebrae (spinous processes) these muscles lie closest to the vertebral column.
variations The spinales are inconstant and are difficult to
separate.
Insertion: Function:
Temporal bone (mastoid process) Capital extension
Occiput (surface below lateral 1/3 of superior nuchal
line)
Description: Innervation:
Fibers directed upward and laterally as a broad band C 3 - T 1 spinal nerves (dorsal rami) (variable)
deep to the rhomboids and trapezius distally and
the sternocleidomastoid proximally. It forms the Cervical Extensor Muscles
floor of the apex of the posterior triangle of the
neck. This group of eight overlapping cervical muscles arise
from the thoracic vertebrae or ribs and insert into
Function: the cervical vertebrae. They are responsible for cervi-
Capital extension cal spine extension in contrast to capital (head) ex-
Rotation of head to same side (debated) tension.
Lateral bending of head to same side
64 Longissimus cervicis
Innervation:
C 3 - C 6 cervical nerves with variations (dorsal 65 Semispinalis cervicis
rami)
66 Iliocostalis cervicis
CT-C2 (suboccipital and greater occipital nerves off
first two dorsal rami) 67 Splenius cervicis
62 SEMISPINALIS CAPITIS 68 Spinalis cervicis
Origin: of 69 Interspinales cervicis
C7 and T L T 6 vertebrae (variable) as series
tendons from tips of transverse processes 70 Intertransversarii cervicis
C4-C6 vertebrae (articular processes)
71 Rotatores cervicis
Insertion:
Occiput (between superior and inferior nuchal lines) 94 Multifidi (see Erector spinae)
Description: 124 Trapezius (see page 3 9 7 )
Tendons unite to form a broad muscle in the up- 127 Levator scapulae (see page 3 9 7 )
per posterior neck, which passes vertically
upward. 64 LONGISSIMUS CERVICIS
Function: Origin:
Capital extension (muscles on both sides) T 1 - T 5 vertebrae (variable) (tips of transverse
Rotation of head to opposite side (debated) processes)
Lateral bending of head to same side
Insertion:
C 2 - C 6 vertebrae (posterior tubercles of transverse
processes)
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Description: 67 SPLENIUS CERVICIS
A continuation of the sacrospinal group, the
tendons are long and thin, and the muscle courses Origin:
upward and slightly medially. The muscles are
bilateral. T 3 - T 6 vertebrae (spinous processes)
Function: Insertion:
Extension of the cervical spine (both muscles)
Lateral bending of cervical spine to same side (one C 1 - C 3 vertebrae (variable) (transverse processes,
muscle) posterior tubercles)
Innervation: Description:
C 3 - T 3 spinal nerves (variable) (dorsal rami) Narrow tendinous band arises from bone and intra-
spinous ligaments and forms a broad sheet
65 SEMISPINALIS CERVICIS along with the splenius capitis. This muscle
ascends upward and laterally under the trapezius
Origin: and rhomboids and medially to the levator
scapulae. The splenii are often absent and are quite
T 1 - T 5 vertebrae (variable) (transverse processes) variable.
Insertion: Function:
Extension of the cervical spine (both muscles)
Axis (C2) to C5 vertebrae (spinous processes) Rotation of cervical spine to same side (one muscle)
Lateral bending to same side (one muscle)
Description: Synergistic with opposite sternocleidomastoid
A narrow, thick muscle arising from a series of
tendons and ascending vertically Innervation:
C 4 - C 8 spinal nerves (variable) (dorsal rami)
Function:
Extension of the cervical spine (both muscles) 68 SPINALIS CERVICIS
Rotation of cervical spine to opposite side (one
muscle) Origin: (spinous
Lateral bending to same side C 6 - C 7 and sometimes T 1 - T 2 vertebrae
processes)
Innervation: Ligamentum nuchae (lower part)
C 2 - T 5 spinal nerves (dorsal rami) (variable)
Insertion:
66 ILIOCOSTALIS CERVICIS Axis (spine)
Origin: C2-C3 vertebrae (spinous processes)
Ribs 3 to 6 (angles); sometimes ribs 1 and 2
also Description:
Insertion: (transverse processes, posterior The smallest and thinnest of the erector spinae, it
C4-C6 vertebrae lies closest to the vertebral column. The erector
tubercles) spinae are inconstant and difficult to separate. This
muscle is often absent.
Function:
Extension of the cervical spine
Description: Innervation:
C 3 - C 8 spinal nerves (dorsal rami) (variable)
Flattened tendons arise from ribs on dorsum of
back and become muscular as they ascend and 69 INTERSPINALES CERVICIS
turn medially to insert on cervical vertebrae. The
muscle lies lateral to the longissimus cervicis. T h e Origin and Insertion:
iliocostales form the lateral column of the Spinous processes of contiguous cervical vertebrae
sacrospinalis group. Six pairs occur: The first pair runs between the axis
and C 3 ; the last pair between C7 and Tl
Function:
Extension of the cervical spine (both muscles) Description:
Lateral bending to same side (one muscle) One of the smallest and least significant muscles but
Depression of ribs (accessory) consists of short, narrow bundles more evident in
cervical spine than at lower levels
Innervation:
C 4 - T 3 spinal nerves (variable) (dorsal rami)
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Function: Muscles of Capital Flexion
Extension of the cervical spine (weak)
The primary capital flexors are the short recti that lie
Innervation: between the atlas and the skull and the longus capitis.
C 3 - C 8 spinal nerves (dorsal rami) (variable) Reinforcing these muscles are the suprahyoid muscles
from the mandibular area.
70 INTERTRANSVERSARII CERVICIS
72 Rectus capitis anterior
Origin and Insertion:
Both anterior and posterior pairs occur at each 73 Rectus capitis lateralis
segment. The anterior muscles interconnect the 74 Longus capitis
anterior tubercles of contiguous transverse
processes and are innervated by the ventral pri- Suprahyoids:
mary rami. The posterior muscles interconnect
the posterior tubercles of contiguous transverse 75 Mylohyoid
processes and are innervated by the dorsal pri-
mary rami. 76 Stylohyoid
Description: 77 Geniohyoid
These muscles are small paired fasciculi that lie
between the transverse processes of contiguous 78 Digastric
vertebrae. The cervicis is the most developed of
this group, which includes the following: the 72 RECTUS CAPITIS ANTERIOR
anterior intertransversarii cervicis; the posterior
intertransversarii cervicis; a thoracic group; and a Origin:
medial and lateral lumbar group. Atlas (C1) (transverse process and anterior surface of
lateral mass)
Function:
Extension of spine (muscles on both sides) Insertion:
Lateral bending to same side (muscles on one side)
Occiput (inferior surface of basilar part)
Innervation: C3-C8 spinal nerves (ventral
Anterior cervicis: C3-C8 spinal nerves (dorsal Description:
rami) Short, flat muscle found immediately behind longus
capitis. Upward trajectory is vertical and slightly
Posterior cervicis: medial.
rami)
Function:
71 ROTATORES CERVICIS Capital flexion
Stabilization of atlanto-occipital joint
(See comments under Rotatores thoracis [No. 95])
Innervation:
Origin: C 1 - C 2 spinal nerves (ventral rami)
Transverse process of one cervical vertebra
73 RECTUS CAPITIS LATERALIS
Insertion:
Base of spine of next highest vertebra Origin:
Atlas (C1) (transverse process, upper surface)
Description:
Insertion:
The rotatores cervicis lies deep to the multifidus Occiput (jugular process)
and cannot be readily separated from it. Both
muscles are irregular and not functionally Description:
significant at the cervical level. Short, flat muscle; courses upward and laterally
Function: Function:
Extension of the cervical spine (assist) Lateral bending of head to same side (obliquity of
Rotation of spine to opposite side muscle)
Assists head rotation
Innervation: Stabilizes atlanto-occipital joint (assists)
C 3 - C 8 spinal nerves (dorsal rami) Capital flexion
Innervation:
C 1 - C 2 spinal nerves (ventral rami)
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74 LONGUS CAPITIS Function: (in
Hyoid bone drawn upward and backward
Origin: (transverse processes, anterior swallowing) of
C3-C6 vertebrae Capital flexion (weak accessory) not
tubercles) Assists in opening mouth (depression
Insertion: mandible)
Occiput (inferior basilar part) Participation in mastication and speech (roles
clear)
Description: Innervation: nerve (posterior trunk, stylohyoid
Starting as four tendinous slips, muscle merges Facial (VII)
and becomes broader and thicker as it rises, branch)
converging medially toward its contralateral
counterpart. 77 GENIOHYOID
Function: Origin: (symphysis menti, inferior mental
Capital flexion Mandible
Rotation of head to same side (muscle of one side) spine)
Innervation: Insertion:
C 1 - C 3 spinal nerves (ventral rami) Hyoid bone (body, anterior surface)
75 MYLOHYOID Description:
Narrow muscle lying superficial to the mylohyoid, it
Origin: from runs backward and somewhat downward. It is in
Mandible (whole length of mylohyoid line contact (or may fuse) with its contralateral
symphysis in front to last molar behind) counterpart at the midline.
Insertion: Function:
Hyoid bone (body, superior surface) Elevation and protraction of hyoid bone
Mylohyoid raphe (from symphysis menti of mandible Capital flexion (weak accessory)
to hyoid bone) Assists in depressing mandible
Description: Innervation:
Flat triangular muscle; the muscles from the two sides CI spinal nerve via hypoglossal ( X I I ) nerve
form a floor for the cavity of the mouth.
Function: 78 DIGASTRIC
Raises hyoid bone and tongue for swallowing
Depresses the mandible when hyoid bone fixed Origin:
Capital flexion (weak accessory) Posterior belly: temporal bone (mastoid notch)
Anterior belly: mandible (digastric fossa)
Innervation: Insertion:
Trigeminal (V) nerve (mylohyoid branch of inferior Intermediate tendon and from there to hyoid bone
alveolar nerve off mandibular division) via a fibrous sling
76 STYLOHYOID Description:
Consists of two bellies united by a rounded
Origin: styloid process (posterolateral intermediate tendon. Lies below the mandible and
Temporal bone, extends as a sling from the mastoid to the
surface) symphysis menti, perforating the stylohyoid, where
the two bellies are joined by the intermediate
Insertion: tendon.
Hyoid bone (body at junction with greater horn)
E M G data show that the two bilateral muscles always
work together.15
Description: Function:
Mandibular depression (muscles on both sides)
Slim muscle passes downward and forward and is Elevation of hyoid bone (in swallowing)
perforated by digastric near its distal attachment. Anterior belly: draws hyoid forward
Muscle occasionally is absent. Posterior belly: draws hyoid backward
Capital flexion (weak synergist)
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Innervation: Description:
Anterior belly: trigeminal (V) nerve (mylohyoid Situated on the anterior surface of the vertebral
branch of inferior alveolar nerve) column from the thoracic spine, rising to the
Posterior belly: facial (VII) nerve, digastric branch cervical vertebrae. It is cylindrical and tapers at
each end.
Cervical Spine Flexors
Function:
The primary cervical spine flexors are the longus Cervical flexion (weak)
colli (a prevertebral mass), the three scalene muscles, Cervical rotation to opposite side (inferior oblique
and the sternocleidomastoid. Superficial accessory head)
muscles are the infrahyoid muscles and the platysma. Lateral bending (superior and inferior oblique heads)
(debatable)
79 Longus colli
Innervation:
80 Scalenus anterior C 2 - C 6 spinal nerves (ventral rami)
81 Scalenus medius The Scalenes
82 Scalenus posterior These muscles are highly variable in their specific
anatomy, and this possibly leads to disputes about
83 Sternocleidomastoid minor functions. Though not described here, a
fourth scalene muscle, the scalenus minimus (of no
88 Platysma functional significance), runs from C7 to the 1st rib
when present.
Infrahyoids:
84 Sternothyroid 80 SCALENUS ANTERIOR
85 Thyrohyoid
86 Sternohyoid Origin: (anterior tubercles of transverse
87 Omohyoid C3-C6 vertebrae
processes)
79 LONGUS COLLI
Insertion:
Has three heads First rib (scalene tubercle on inner border and ridge
on upper surface)
Superior oblique:
Origin: (anterior tubercles of transverse Description:
C3-C5 vertebrae Lying deep at the side of the neck under the
processes) sternocleidomastoid, it descends vertically.
Attachments are highly variable.
Insertion: A fourth scalene (scalenus minimus) is occasionally
Atlas (tubercle on anterior arch) associated with the cervical pleura and runs from
C7 to the 1st rib.
Inferior oblique:
Origin: Function:
Flexion of cervical spine (both muscles)
T 1 - T 3 vertebrae (variable) (anterior bodies) Elevation of 1st rib in inspiration
Rotation of cervical spine to same side
Insertion: Lateral bending of neck to same side
C5-C6 vertebrae (anterior tubercles of transverse Innervation:
processes) C 4 - C 6 cervical nerves (ventral rami)
Vertical portion:
Origin: 81 SCALENUS MEDIUS
T 1 - T 3 and C 5 - C 7 vertebrae (anterolateral bodies)
(variable) Origin:
C2-C7 (posterior
processes) tubercles of transverse
Atlas (sometimes)
Insertion:
C2-C4 vertebrae (anterior bodies)
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Insertion: Function:
1st rib (widely over superior surface)
Flexion of cervical spine (both muscles)
Description: Descends Lateral bending of cervical spine to same side
Longest and largest of the scalenes. Rotation of head to opposite side
vertically along side of vertebrae. Capital extension (posterior fibers)
Raises sternum in forced inspiration
Function: Innervation: nerves (ventral
Cervical flexion (weak) Accessory (XI) nerve (spinal part)
Lateral bending of cervical spine to same side C 2 - C 3 (sometimes C 4 ) cervical
Elevation of 1st rib in inspiration rami)
Cervical rotation to same side
Innervation: 84 STERNOTHYROID
C3-C8 cervical nerves (ventral rami)
Origin:
82 SCALENUS POSTERIOR Sternum (manubrium, posterior surface)
1st rib (cartilage)
Origin: posterior tubercles of Insertion:
C4-C6 vertebrae (variable; Thyroid cartilage (oblique line)
transverse processes)
Insertion: Description:
2nd rib (outer surface) A deep-lying, somewhat broad muscle rising verti-
cally and slightly laterally just lateral to the thyroid
gland
Description: Function:
Smallest and deepest lying of the scalene muscles. Cervical flexion (weak)
Attachments are highly variable. Often not Draws larynx down after swallowing or vocalization
separable from scalenus medius. Depression of hyoid, mandible, and tongue (after
elevation)
Function:
Cervical flexion (weak) Innervation:
Elevation of 2nd rib in inspiration C 1 - C 3 cervical nerves (branch of ansa cervicalis)
Lateral bending of cervical spine to same side 85 THYROHYOID
(accessory)
Origin:
Cervical spine rotation to same side Thyroid cartilage (oblique line)
Innervation:
C6-C8 cervical nerves (ventral rami)
83 STERNOCLEIDOMASTOID Insertion:
Origin: Hyoid bone (inferior border of greater horn)
Sternal (medial) head: sternum (manubrium, ventral
surface) Description:
Clavicular (lateral) head: clavicle (superior and
anterior surface of medial 1/3) Appears as an upward extension of sternothyroid. It
is a small rectangular muscle lateral to the thyroid
Insertion: cartilage.
Temporal bone (mastoid process, lateral surface)
Occiput (lateral half of superior nuchal line) Function:
Cervical flexion (This small muscle is attached to
Description: mobile structures and its role in cervical flexion
seems unlikely as a functional entity.)
The two heads of origin gradually merge in the neck Draws hyoid bone downward
as the muscle rises upward laterally and posteriorly. Elevates larynx and thyroid cartilage
Their oblique (lateral to medial) course across the
sides of the neck is a very prominent feature of Innervation:
surface anatomy. Hypoglossal (XII) and branches of C1 spinal nerve
(which run in hypoglossal nerve)
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86 STERNOHYOID Innervation:
Hypoglossal ( X I I ) (ansa cervicalis) via C1
Origin: (branches from ansa cervicalis) and C 2 - C 3 cervical
Clavicle (medial end, posterior surface) nerves
Sternum (manubrium, posterior)
Sternoclavicular ligament 88 PLATYSMA
Insertion: Origin:
Hyoid bone (body, lower border) Fascia covering upper pectoralis major and deltoid
Description: Insertion:
Thin strap muscle that ascends slightly medially from Mandible (below the oblique line)
clavicle to hyoid bone Modiolus10-12
Skin and subcutaneous tissue of lower lip and face
Function: Contralateral muscles join at midline
Cervical flexion (weak)
Depresses hyoid bone after swallowing Description:
A broad sheet of muscle, it rises from the shoulder,
Innervation: (branches of ansa crosses the clavicle, and rises obliquely upward and
Hypoglossal (XII) nerve medially to the side of the neck.
C1-C3 cervical nerves The muscle is very variable.
cervicalis)
Function:
87 OMOHYOID Draws lower lip downward and backward (expres-
sion of surprise or horror) and assists with jaw
Has two bellies opening.
Is a weak cervical flexor, Electromyogram shows
Inferior belly: great activity in extreme effort and in sudden
deep inspiration.16
Origin: extent; Can pull skin up from clavicular region, increasing
under diameter of neck. Wrinkles skin of nuchal area
Scapula (superior margin to variable obliquely, thereby decreasing concavity of neck.
subscapular notch) Assists in forced inspiration.
Platysma is not a very functional muscle.
Superior transverse ligament
Innervation:
Insertion: omohyoid Facial (VII) nerve (cervical branch)
Intermediate tendon of
sternocleidomastoid MUSCLES OF THE TRUNK
Clavicle by fibrous expansion
Back
Superior belly: Thorax (respiration)
Abdomen
Origin: Perineum and anus
Intermediate tendon of omohyoid
Deep Muscles of the Back
Insertion:
Hyoid bone (lower border of body) These muscles consist of groups of serially arranged
muscles ranging from the occiput to the sacrum. There-
Description: are four subgroups plus the quadratus lumborum.
Muscle consists of two fleshy bellies united at an
angle by a central tendon. The inferior belly is a In this section readers will note that the cervical
narrow band that courses forward and slightly portions of each muscle group are not included.
upward across the lower front of the neck. The These muscles are described as part of the neck mus-
superior belly rises vertically and lateral to the cles because their functions involve capital and cervi-
sternohyoid. cal motions. They are, however, mentioned in the
identification of each group for a complete overview.
Function:
Depression of hyoid after elevation
Cervical flexion
No E M G data to support function
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Part 3. Skeletal Muscles of the Human Body
Splenius (in neck only) Iliocostalis column (lateral)
Erector spinae 66 Iliocostalis cervicis (see Muscles of the Neck)
Transversospinalis group
Interspinal-intertransverse group 89 ILIOCOSTALIS THORACIS
Quadratus lumborum
Origin:
Erector Spinae Ribs 12 to 7 (upper borders at angles)
The muscles of this group cover a large area of the Insertion:
back, extending laterally from the vertebral column Ribs 1 to 6 (at angles)
to the angle of the ribs and vertically from the C7 (transverse process, dorsum)
sacrum to the occiput. This large musculotendinous
mass is covered by the serratus posterior inferior and Innervation:
thoracodorsal fascia below the rhomboid and sple- T 1 - T 1 2 spinal nerves
nius muscles above. The erector spinae vary in size
and composition at different levels. 90 ILIOCOSTALIS LUMBORUM
Sacral region: Strong, dense, tendinous sheet; narrow Origin: spinae (anterior
at base (common tendon) Common tendon of erector
Lumbar region: Expands into thick muscular mass surface)
(palpable); visible surface contour on lateral Thoracolumbar fascia
side Iliac crest (external lip)
Sacrum (posterior surface)
Thoracic region: Muscle mass much thinner than that
found in lumbar region; surface groove along Insertion:
lateral border follows costal angles until covered Lumbar vertebrae (all) (transverse processes)
by scapula Ribs 5 or 6 to 12 (angles on inferior border)
Common Tendon of Erector Spinae: Description (All Iliocostals):
This is the origin of the broad thick tendon as This is the most lateral column of the erector spinae.
described in Grant7: The lumbar portion of this muscle is the largest,
Sacrum (median and lateral crests, anterior surface and it subdivides as it ascends.
of the tendon of erector spinae); L1-L5 and T 1 2
vertebrae (spinous processes); supraspinous, Function:
sacrotuberous, and sacroiliac ligaments; iliac crests Extension of spine
(inner aspect of dorsal part). Lateral bending of spine (muscles on one side)
Depression of ribs (lumborum)
From the common tendon the muscles rise to form Elevation of pelvis
a large mass that is divided in the upper lumbar
region into three longitudinal columns based on
their areas of attachment in the thoracic and
cervical regions.
Lateral column of muscle Innervation:
66 Iliocostalis cervicis (see Muscles of the Neck) L 1 - L 5 spinal nerves, dorsal rami (variable)
89 Iliocostalis thoracis
90 Iliocostalis lumborum 91 LONGISSIMUS THORACIS
Intermediate column of muscle Origin: and accessory
60 Longissimus capitis (see Muscles of the Neck) Thoracolumbar fascia
64 Longissimus cervicis (see Muscles of the L1-L5 vertebrae (transverse
Neck) processes)
91 Longissimus thoracis
Insertion:
Medial column of muscle T 1 - T 1 2 vertebrae (transverse processes)
63 Spinalis capitis (see Muscles of the Neck) Ribs 2 to 12 (between tubercles and angles)
68 Spinalis cervicis (see Muscles of the Neck)
92 Spinalis thoracis Description (All Longissimi):
These are the intermediate erector spinae. They lie
between the iliocostales (laterally) and the spinales
(medially). The fibers of the longissimus are
inseparable from those of the iliocostales until the
upper lumbar region.
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Part 3. Skeletal Muscles of the Human Body
Function (Longissimus Thoracis): Description:
Extension of the spine This group is found only in the thoracic and cervical
Lateral bending of spine to same side (muscles on regions, extending to the head. They lie deep to
one side) the spinalis and longissimus columns of the erector
Depression of ribs spinae.
Innervation: Function:
T l - L l spinal nerves (dorsal rami) Extension of thoracic spine
92 SPINALIS THORACIS Innervation:
T 1 - T 1 2 spinal nerves (dorsal rami), variable
Origin: and L1-L2 vertebrae (spinous
T11-T12 94 MULTIFIDI
processes)
Origin:
Insertion: Sacrum (posterior, as low as the S4 foramen)
T 1 - T 4 or through T8 vertebrae (spinous Aponeurosis of erector spinae
processes) Ilium (posterior superior iliac spine) and adjacent
crest
Description: Sacroiliac ligaments (posterior)
The smallest and thinnest of the erector spinae, L1-L5 vertebrae (mamillary processes)
they lie closest to the vertebral column. T h e T 1 - T 1 2 vertebrae (transverse processes)
spinales are inconstant, and are difficult to C4-C7 vertebrae (articular processes)
separate.
Insertion:
Function: A higher vertebra (spinous process): Most superficial
Extension of spine fibers run to the third or fourth vertebra above;
middle fibers run to the second or third vertebra
Innervation: above; deep fibers run between contiguous
T 1 - T 1 2 (variable) dorsal rami vertebrae.
Transversospinales Group Description:
These muscles fill the grooves on both sides of the
Muscles of this group lie deep to the erector spinae, spinous processes of the vertebrae from the sacrum
filling the concave region between the spinous and to the middle cervical vertebrae (or may rise as
transverse processes of the vertebrae. They ascend high as C I ) . They lie deep to the erector spinae
obliquely and medially from the vertebral transverse in the lumbar region and deep to the semispinalis
processes to adjacent and sometimes more remote above. Each fasciculus ascends obliquely, traversing
vertebrae. A span over four to six vertebrae is not over two to four vertebrae as it moves toward the
uncommon. midline to insert in the spinous process of a higher
vertebra.
62 Semispinalis capitis (see Muscles of the Neck)
Function:
65 Semispinalis cervicis (see Muscles of the Extension of spine
Neck) Lateral bending of spine (muscle on one side)
Rotation to opposite side
93 Semispinalis thoracis
Innervation:
94 Multifidi Spinal nerves (whole length of spine), segmentally
(dorsal rami)
71 Rotatores cervicis (see Muscles of the Neck)
The Rotatores
95 Rotatores thoracis
The rotatores are the deepest muscles of the
96 Rotatores lumborum transversospinales group, lying as 11 pairs of very
short muscles beneath the multifidi. The fibers run
93 SEMISPINALIS THORACIS obliquely upward and and medially or almost hori-
zontal. They may cross more than one vertebra on
Origin: their ascending course, but most commonly they
T 6 - T 1 0 vertebrae (transverse processes) proceed to the next higher one. Found along the en-
Insertion:
C6-T4 vertebrae (spinous processes)
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Part 3. Skeletal Muscles of the Human Body
tire length of the vertebral column, they are distin- sions as seen in the other spine areas and are not
guishable as developed muscles only in the thoracic constant.
area.
69 Interspinales cervicis (see Muscles of the
Neck)
95 ROTATORES THORACIS 70 Intertransversarii cervicis, anterior and posterior
(see Muscles of the Neck)
Origin:
Tl to T 1 2 vertebrae (transverse processes) 97 Interspinales thoracis
Insertion: 98 Interspinales lumborum
Vertebra above (lamina)
99 Intertransversarii thoracis
Description: 99 Intertransversarii lumborum, medial and
There are 11 pairs of these small muscles. lateral
Adjacent muscles start from the posterior
transverse process of one vertebra and rise to attach 97 INTERSPINALES THORACIS
to the lower body and lamina of the next higher
vertebra. Origin and Insertion:
Between spinous processes of contiguous vertebrae
Function: Three pairs are reasonably constant: (1) between
Extension of thoracic spine the 1st and 2nd thoracic vertebrae; (2) between
Rotation to opposite side the 2nd and 3rd thoracic vertebrae (variable);
(3) between the 11th and 12th thoracic
Innervation vertebrae
T 1 - T 1 2 spinal nerves (dorsal rami)
96 ROTATORES LUMBORUM Function:
Extension of spine
The rotatores are highly variable and irregular in
these regions. Innervation: (irregular) spinal nerves (dorsal
T1-T3; T11-T12
rami)
Description 98 INTERSPINALES LUMBORUM
This muscle lies deep to the multifidi and cannot be
readily separated from the deepest fibers of the Origin:
multifidi. Pattern is similar to the thoracis. There are four pairs lying between the five lumbar
vertebrae. Fasciculi run from the spinous processes
Function: (superior) of L2-L5.
Extension of spine
Rotation of spine to opposite side Insertion:
To inferior surface of spinous process of the vertebra
Innervation: nerves (dorsal rami) (highly above the vertebra of origin
L 1 - L 5 spinal
variable) Function:
Extension of spine
Interspinal-Intertransverse Group
Innervation:
The short, paired muscles in the interspinales group L 1 - L 4 spinal nerves (dorsal rami), variable
pass segmentally from the spinous processes (superior
surface) of one vertebra to the inferior surface of the 99 INTERTRANSVERSARII THORACIS
next on either side of the interspinous ligament. AND LUMBORUM
They are most highly developed in the cervical re-
gion, and quite irregular in distribution in the tho- Intertransversarii thoracis
racic and lumbar spines.
Origin:
The intertransversarii are small fasciculi lying be- T11-L1 (transverse processes, superior surfaces)
tween the transverse processes of contiguous verte-
brae. They are most developed in the cervical spine.
The cervical muscles have both anterior and posterior
parts; the lumbar muscles have medial and lateral
fibers. The thoracic muscles are single without divi-
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Part 3. Skeletal Muscles of the Human Body
Insertion: L1-L4 vertebrae (apices of transverse processes)
T 1 0 - T 1 2 (transverse processes, inferior surfaces) T 1 2 vertebral body (occasionally)
Function: one Description:
An irregular quadrilateral muscle located against the
Extension of spine (muscles on both sides) posterior (dorsal) abdominal wall, this muscle is
Lateral bending to same side (muscles on encased by layers of the thoracolumbar fascia. It
fills the space between the 12th rib and the iliac
side) crest. Its fibers run obliquely upward and medially
Rotation to opposite side from the iliac crest to the inferior border of the
Innervation: 12th rib and transverse processes of the lumbar
vertebrae. The muscle is variable in size and
T 1 - T 1 2 , L1-L5 spinal nerves (dorsal rami) occurrence.
Intertransversarii lumborum—medial Function:
Elevation of pelvis (weak in contrast to lateral
Origin: abdominals)
Extension of lumbar spine (muscles on both sides)
L2-S1 vertebrae (accessory processes) Inspiration (via stabilization of lower attachments of
diaphragm)
Insertion: Fixation of lower portions of diaphragm for
prolonged vocalization that needs sustained
Vertebra above the vertebra of origin (mamillary expiration
processes) Lateral bending of lumbar spine to same side (pelvis
fixed)
Function: Fixation and depression of 12th rib
Lateral bending of lumbar spine
Most likely function is postural Innervation:
T 1 2 - L 3 spinal nerves (ventral rami)
Innervation:
Lumbar and sacral spinal nerves (dorsal rami) Muscles of the Thorax for Respiration
Intertransversarii lumborum—lateral 101 Diaphragm
(two portions)
102 Intercostales externi
Origin:
Ventral portion: L2-S1 vertebrae (costal processes, 103 Intercostales interni
ventral part)
Dorsal portion: L2-S1 vertebrae (accessory processes, 104 Intercostales intimi
superior part)
105 Subcostales
Insertion:
Ventral portion: vertebra above the vertebra of origin 106 Transversus thoracis
(costal processes, inferior surfaces)
Dorsal portion: vertebra above the vertebra 107 Levatores costarum
of origin (transverse processes, inferior 108 Serratus posterior superior
surfaces)
109 Serratus posterior inferior
Function: stabilization of adjacent
Postural function and 101 DIAPHRAGM
vertebrae
Extension of the spine Origin:
Muscle fibers originate from the circumference of the
Innervation: thoracic outlet in three groups:
Lateral muscles: lumbar and sacral spinal nerves Sternal: Xiphoid (posterior surface)
(ventral rami) Costal: Ribs 7 to 12 (bilaterally; inner surfaces
of the cartilage and the deep surfaces on each
100 QUADRATUS LUMBORUM side)
Lumbar: L 1 - L 3 vertebrae from the medial and
Origin: lateral arcuate ligaments (also called lumbocostal
Ilium (crest, inner lip) arches) and from bodies of the vertebrae by two
Iliolumbar ligament muscular crura
Insertion:
12th rib (lower border)
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