Depressor labii Masseter
inferioris A muscle of mastication
(chewing); it also raises the jaw
Pulls the lower lip and brings the teeth together
downward
Risorius
Mentalis Pulls on the corners of the mouth
Raises the lower lip, to produce an unpleasant grin
producing a thoughtful or
doubtful expression Orbicularis oris
Muscle fibers encircle the
Sternal head of mouth and bring lips together;
sternocleidomastoid when they contract more
strongly, they form a pout
Clavicular head of
sternocleidomastoid Depressor anguli oris
Turns the head to the side Pulls down the corners of the
mouth to form a sad expression
Trapezius
Attaches from the skull and Superior belly of omohyoid
spine to the scapula and Levator scapulae
clavicle; it can perform Attaches from cervical spine
to top of scapula; it can raise
several actions, including the scapula or flex the neck
flexing the neck to the side to the side
and drawing the head Anterior scalene
backward Attaches from cervical
spine to first rib; flexes the
neck forward or to the side
Sternohyoid
Pulls the hyoid bone down after
it has been raised in swallowing
Inferior belly of omohyoid
100 Frontal belly of
occipitofrontalis
ANATOMY Orbicularis oculi
Latin for circular
HEAD muscle of the eye
AND NECK Levator labii
MUSCULAR superioris
alaeque nasi
The muscles of mastication (chewing) attach from In Latin, lifter of
the skull to the mandible ( jawbone), operating to the upper lip
open and shut the mouth, and to grind the teeth and the wing
together to crush the food we eat. In this side view, (nostril) of the nose
we can see the two largest muscles of mastication, Levator labii
the temporalis and masseter muscles. Two smaller superioris
muscles attach to the inner surface of the mandible. Literally, lifter of
Human jaws don’t just open and close, they also the upper lip
move from side to side, and these four muscles Nasalis
act in concert to produce complex chewing Means of the nose
movements. In this view, we can also see how in Latin
the frontal bellies (fleshy central parts) of the
occipitofrontalis muscle are connected to occipitalZygomaticus major
bellies at the back of the head by a thin, flat Attaches from the
tendon, or aponeurosis. This makes the entire zygomatic arch
scalp movable on the skull. (cheek bone)
Epicranial SIDE
aponeurosis
Temporalis
Attaches from the temporal bone
of the skull to the coronoid process
of the mandible ( jawbone)
Occipital belly of
occipitofrontalis
Splenius capitis Masseter Orbicularis oris
Named after the Latin for From the Greek for chewer Latin for circular
bandage of the head, this muscle of the mouth
Anterior belly of digastric
muscle draws the head Digastric means two-bellied Risorius
backward From the Latin
Posterior belly of digastric for laughter
Sternocleidomastoid The digastric pulls the mandible
Turns the head to the side (upper jaw bone) down to open Depressor labii
the mouth, and pulls the hyoid inferioris
Inferior constrictor bone up in swallowing The depressor
of pharynx of the lower lip
Trapezius Mentalis
This means of the
Levator scapulae chin in Latin
This is Latin for lifter of
Depressor
the shoulder blade anguli oris
Literally, the
Middle scalene depressor
of the corner of
Anterior scalene the mouth
The scalene muscles are
shaped like scalene
triangles (where each
side is a different length)
Posterior scalene
Thyrohyoid
Attaches from the hyoid
bone to the thyroid
cartilage of the larynx
Superior belly of omohyoid
Omo comes from the Greek for
shoulder; this muscle is named
after its attachments—from the
hyoid bone to the shoulder blade
Sternohyoid
Attaches from the sternum
to the hyoid bone
Sternothyroid
Attaches from the sternum
to the thyroid cartilage
Inferior belly of omohyoid
101
HEAD AND NECK • MUSCULAR
102 SAGITTAL SECTION
ANATOMY Palatoglossal fold
Pharyngotympanic tube Palatine tonsil
Also known as the auditory Palatopharyngeal fold
or eustachian tube; a
slender muscle called
salpingopharyngeus
descends from its cartilage
to contribute to the side
wall of the pharynx
Soft palate
A pair of muscles sweep
down from the base of the
skull on either side, into
the soft palate; two others
leave the palate and run
down into the tongue and
the pharynx
Genioglossus
Attaches from
the inside of the
mandible and
sweeps up into
the tongue
Hard palate
Geniohyoid
One of a pair of slender
muscles lying side-by-side in
the floor of the mouth that
stretch from the mandible
to the hyoid bone
Mylohyoid Hyoid bone Cricoid cartilage Epiglottis
One of a pair of Thyroid gland The lowest cartilage One of the cartilages
muscles forming a in the larynx of the larynx; it helps
sheet that forms the protect the laryngeal
floor of the mouth inlet during
swallowing
Thyroid cartilage
The largest cartilage Pharynx
A fibromuscular tube
of the larynx that extends from the
base of the skull to
Trachea the esophagus, and
The posterior wall of opens forward into
the trachea is formed the nasal cavity, oral
cavity, and larynx
by the trachealis
muscle Vocal cord
Several small muscles
within the larynx act on
the vocal cords to move
them closer together or
farther apart, or to
tense them
Esophagus
A muscular tube that
stretches from the pharynx
to the stomach
103
HEAD AND NECK • MUSCULAR
Stylohyoid Pharyngobasilar fascia HEAD AND NECK
ligament Stretches between the top MUSCULAR
of the superior constrictor
Superior constrictor and the base of the skull In the section through the head (opposite), we see the soft palate, tongue, pharynx, and
of the pharynx larynx, all of which contain muscles. The soft palate comprises five pairs of muscles.
Stylopharyngeus When relaxed, it hangs down at the back of the mouth but, during swallowing, it
Takes its attachments Descends from the styloid thickens and is drawn upward to block off the airway. The tongue is a great mass of
from the base of process into the pharynx muscle, covered in mucosa. Some of its muscles arise from the hyoid bone and the
mandible, and anchor it to these bones and move it around. Other muscle fibers are
the skull and from Middle constrictor of entirely within the tongue and change its shape. The pharyngeal muscles are important
the mandible the pharynx in swallowing, and the laryngeal muscles control the vocal cords. The muscles that
Attaches from the hyoid move the eye can be seen on p.116.
Pharyngeal raphe bone on either side
The fibers of the Thyroid cartilage
Cricopharyngeus The largest cartilage
constrictor muscles The lowest part of the of the larynx
sweep back from their inferior constrictor; forms
anterior attachments to a sphincter just before the Vocal cord
start of the esophagus that Thyrohyoid
insert into this raphe stops you from
(seam in Greek) continually swallowing air Omohyoid
as you breathe
Inferior constrictor Glottis
of the pharynx The gap between the
Attaches from the vocal cords; muscles
larynx of the larynx act to
change the position
Longitudinal muscle Circular muscle of and tension of the
of the esophagus the esophagus vocal cords
PHARYNX POSTERIOR (BACK) Inferior constrictor
Platysma Longus colli
This very thin sheet of
Body of cervical
muscle lies in the vertebra
superficial fascia over
the front of the neck, Subarachnoid
space
and produces
a grimace Spinal cord
Sternohyoid Epidural space
Sternothyroid Spinous process of
cervical vertebra
Sternocleidomastoid
Connecting the Subcutaneous fat
mastoid process of
the skull above to the
clavicle and sternum
below, this muscle turns
the head to the side
Anterior scalene
Middle scalene
The scalene muscles
attach from the cervical
spine down to the
upper ribs; they flex
the neck forward or
to the side
Levator scapulae
Attaches from the
cervical spine to
the scapula
Splenius capitis
Acts to draw the head
backward
Multifidus
Semispinalis capitis
Extends or tips back the
head on the neck
Semispinalis cervicis
Extends or arches the
neck backward
Trapezius
TRANSVERSE SECTION OF THE NECK AT THE VOCAL CORDS
104
ANATOMY
HEAD AND NECK Superior frontal gyrus
NERVOUS The word gyrus comes from the
Latin for ring or convolution, and
Compared to other animals, humans have massive brains for the size is a term used for the scroll-like
of our bodies. The human brain has grown larger and larger over the
course of evolution, and it is now so overblown that the frontal lobes folds of the cerebral cortex
of the brain lie right over the top of the orbits that contain the eyes.
Think about any other mammal, perhaps a dog or a cat for easy Middle frontal gyrus
reference, and you will quickly realize what an odd shape the human
head is—and most of that is a result of our huge brains. Looking at Inferior frontal gyrus
a side view of the brain, you can see all the lobes that make up each Includes Broca’s area, part of the
cerebral hemisphere: the frontal, parietal, temporal, and occipital cerebral cortex that is involved with
lobes (individually colored, below). Tucked under the cerebral
hemispheres at the back of the brain is the cerebellum (Latin for generating speech
little brain). The brain stem leads down, through the foramen
magnum of the skull, to the spinal cord.
Olfactory bulb
Optic nerve
The second cranial nerve. It
carries nerve fibres from the
retina to the optic chiasma
Central Parietal
sulcus lobe
Frontal Parieto-occipital
lobe sulcus
Frontal Lateral
pole sulcus
Lateral Occipital
cerebral pole
fossa Occipital
lobe
Temporal
pole LOBES AND POLES
Temporal
lobe
Inferior temporal 105
sulcus
HEAD AND NECK • NERVOUS
Pons
Derived from Latin for Precentral gyrus
bridge, this is the part The location of the primary
motor cortex—where nerve
of the brain stem impulses that lead to muscle
between the midbrain movement originate
and the medulla Precentral sulcus
Divides off the precentral
SIDE VIEW OF BRAIN gyrus from the rest of the
frontal lobe
Central sulcus
The division between the
frontal and parietal lobes
Postcentral gyrus
Lies just behind the central
sulcus. The primary
somatosensory cortex, which
receives sensory information
from all over the body
Postcentral sulcus
Separates the postcentral
gyrus from the rest of the
parietal lobe
Lateral sulcus
A deep cleft dividing the frontal
and parietal lobes from the
temporal lobe below
Superior temporal gyrus
Includes the primary auditory
cortex, where sensory
information related to
hearing is received
Superior temporal sulcus
Sulcus is a Latin word
meaning groove or furrow
Middle temporal gyrus
Inferior temporal gyrus
Preoccipital notch
Cerebellum
Sits under the occipital lobes
at the back of the brain;
responsible for coordinating
movement and managing
balance and posture
Medulla oblongata
The lowest part of the brain
stem; it continues down to
form the spinal cord.
Contains important centers
involved in controlling
breathing, heart rate, and
blood pressure
Spinal cord
106
ANATOMY
HEAD AND NECK From an anatomist’s point of view, the brain is emerge from the brain itself. To the naked eye,
NERVOUS quite an ugly and unprepossessing organ. It looks there is little to suggest that the brain is the most
rather like a large, pinkish gray, wrinkled walnut— complicated organ in the human body. Its true
especially when viewed from above. The outer complexity is only visible through a microscope,
layer of gray matter, called the cortex, is highly revealing billions of neurons that connect with
folded. Underneath the brain we see some more each other to form the pathways that carry our
detail, including some of the cranial nerves that senses, govern our actions, and create our minds.
Longitudinal Frontal pole
(cerebral) fissure Superior frontal sulcus
A deep cleft dividing Inferior frontal sulcus
the two cerebral
hemispheres
Middle frontal gyrus
Inferior frontal gyrus Superior frontal gyrus
Precentral sulcus Cingulate sulcus
Precentral gyrus Superior parietal lobule
Postcentral gyrus
Intraparietal sulcus
Central sulcus Divides the superior from the
inferior parietal lobule
Supramarginal gyrus
Many parts of the cortex Superior temporal sulcus
are “association areas,” Angular gyrus
involved with processing Turns a corner around the end
sensory information and of the superior temporal sulcus.
Studies of brain function suggest
perception. This gyrus, this area may be important in
on the left, has been mathematical problem-solving
and understanding metaphors
shown to be important
in understanding spoken Inferior parietal lobule
language, learning new Parieto-occipital sulcus
vocabulary, and reading Divides the parietal and
occipital lobes
Postcentral sulcus
Occipital pole
TOP VIEW OF BRAIN
Frontal pole 107
Longitudinal HEAD AND NECK • NERVOUS
(cerebral) fissure
Olfactory bulb
Straight gyrus Receives olfactory nerves,
which have emerged from
Orbital gyri the top of the nasal cavity
Lie around the edges of through the cribiform
plate of the ethmoid
the H-shaped orbital bone, to enter the inside
sulcus, and seem to play of the skull
some role in empathy Olfactory tract
Carries olfactory (smell)
Temporal pole information back to
Pituitary gland the uncus
Parahippocampal gyrus
This part of the cortex, Orbital sulcus
close to the hippocampus,
plays an important role in Optic chiasma
memory and recognition Where the two optic
nerves meet and swap
Tuber cinereum fibres with each other,
Small bump of to form the optic tracts;
chiasma means a cross
gray matter under the
brain; part of the Lateral cerebral fossa
hypothalamus (see p.110) Olfactory trigone
The olfactory tract splays
Uncus out into this triangular
Hooked-under end of the shape, just in front of
the anterior perforated
parahippocampal gyrus; substance
contains the primary
Inferior temporal
olfactory cortex, receiving sulcus
olfactory (smell)
information Anterior perforated
substance
Interpeduncular fossa Area of gray matter
Area enclosed by the between the olfactory
cerebral peduncles on trigone, the optic
each side, by the chiasma, and the uncus;
pierced by small arteries
optic chiasma in front, from the anterior and
and the pons of the middle cerebral arteries
brain stem behind
Mammillary bodies
Medial and lateral Two breast-like bumps
occipitotemporal gyri that are part of the limbic
system, which is involved
Inferior temporal in memory, emotions,
gyrus and behaviour
Parahippocampal Cerebral peduncle
gyrus “Stalk” of the brain,
containing motor nerve
Spinal cord fibres that descend from
the cerebral cortex to the
Occipital pole brain stem and spinal cord
Pons
Cerebellum
Pyramid
A prominence on
the front of medulla
containing motor nerve
fibres that run from the
cortex of the brain
to the spinal cord
UNDERSIDE OF BRAIN
108 Corpus callosum
Forms a bridge
ANATOMY between the
two cerebral
Longitudinal hemispheres
(cerebral)
fissure Olfactory bulb
Olfactory tract
Frontal lobe
Temporal pole
Frontal pole
Pituitary gland
Lateral sulcus Horizontal
fissure of
Temporal lobe cerebellum
Optic nerve Spinal cord
Optic chiasma FRONT VIEW OF BRAIN
Where the optic
nerves partially
cross each other
Pons
Cerebellar
hemisphere
Medulla
oblongata
HEAD AND
NECK NERVOUS
The largest part of the brain, the cerebrum, is almost completely
divided into two cerebral hemispheres. This division is clearly seen
when viewing the brain from the front, back, or top. The fissure
between the hemispheres runs deep, but at the bottom of it lies the
corpus callosum, which forms a bridge between the two sides. Areas
of the brain that receive and process certain types of information,
or govern movements, can be very widely separated. The visual
pathways from the eyes end in the cortex of the occipital lobe at the
back of the brain, and visual information is also processed in this
lobe. But the nerve impulses that eventually reach the muscles to
move the eyes begin in the cortex of the brain’s frontal lobe.
Longitudinal 109
(cerebral)
fissure HEAD AND NECK • NERVOUS
Occipital pole Parietal lobe
Cerebellar vermis
The median part of Corpus callosum
the cerebellum Occipital lobe
between the two
Fissures
hemispheres The grooves in
Medulla the cerebellum
Folia
oblongata The bulges in
The lowest the cerebellum
part of the Cerebellar
brain stem hemisphere
Like the cerebrum,
the cerebellum has
two hemispheres
Horizontal
fissure of
cerebellum
The deepest
fissure in the
cerebellum
Spinal cord
BACK VIEW OF BRAIN
110
ANATOMY
Body of corpus callosum
The largest commissure (or bundle of connecting
nerve fibers) between the two hemispheres, this
forms the roofs of the lateral ventricles
Septum pellucidum
This “translucent partition” is a
thin dividing wall between the
two lateral ventricles
Superior frontal gyrus
Cingulate gyrus
“Cingulum” is the Latin for girdle and this gyrus
wraps closely around the corpus callosum; it is
part of the limbic system, which is involved with
emotional responses and behaviors
Genu of corpus callosum
The anterior (front) end of the corpus callosum
is bent over—“genu” means knee in Latin
Anterior commissure
A bundle of nerve fibers connecting
parts of the two cerebral hemispheres
Optic chiasma
The crossover point where the two optic nerves
meet and swap fibers, then part company as
the optic tracts, which continue on each side of
the brain toward the thalamus
Hypothalamus
Plays an important role in regulating the
internal environment of the body, by keeping
a check on body temperature, blood pressure,
and blood sugar level, for instance
Pituitary gland
Produces many hormones and
forms a link between the brain
and endocrine system
Mammillary body
Part of the limbic system of the brain
SAGITTAL SECTION
THROUGH BRAIN
111
HEAD AND NECK • NERVOUS
Interthalamic adhesion
Connection between the thalami
on each side of the brain
Cerebrum
The largest part of the brain, consisting of the two
cerebral hemispheres
Thalamus
Processes and relays sensory and motor
information to higher brain centers
Splenium of corpus callosum
The posterior end of the corpus callosum
Choroid plexus of the third ventricle
A choroid plexus is formed where the inner and outer
membranes of the brain come together; it is full of
capillaries and produces cerebrospinal fluid, which
flows into the ventricle
Pineal gland
Produces the hormone melatonin and is involved
in the regulation of sleep–wake cycles
Superior colliculus
Involved in visual reflex pathways, including the
pupillary light reflex, which makes the pupils constrict
when bright light hits the retina
Tectum of the midbrain
The roof of the midbrain
Cerebral aqueduct
A narrow channel connecting
the third and fourth ventricles
Inferior colliculus
Involved with auditory pathways, including
reflex responses to loud noises
Tegmentum of midbrain
Fourth ventricle
Pons
Median aperture of the fourth ventricle
Cerebrospinal fluid escapes from the fourth ventricle
via this opening in the midline, as well as through an
opening on each side, into the subarachnoid space
around the brain and spinal cord
Cerebellum
Medulla oblongata
Spinal cord
HEAD AND NECK
NERVOUS
This median sagittal section—a vertical slice right through the middle of the brain—
shows clearly the corpus callosum, which links the two hemispheres. We also see that
the brain is not solid: there are cavities within it. Two spaces (or ventricles) lie inside
each hemisphere, while the third and fourth ventricles are located on the midline.
These spaces are full of cerebrospinal fluid. Beneath and behind the cerebrum sits
the cerebellum. The gray cortex of the cerebellum is more finely folded than that of
the cerebrum, with fissures separating its leaves (or folia). Sliced through this way, the
inside of the cerebellum reveals a beautiful, treelike pattern. In this section, we can
also see clearly all the parts of the brainstem—the midbrain, pons, and medulla.
112 Genu of corpus
callosum
ANATOMY
Internal capsule
Anterior horn Area that contains
of lateral many motor
ventricle nerve fibers,
descending from
Septum the motor cortex
pellucidum and heading for
the brain stem
Caudate and spinal cord
nucleus
Part of the basal Lentiform
ganglia, this nucleus
“tailed” nucleus Another part of
helps control the basal ganglia;
and smooth out lentiform means
movement lentil shaped
Fornix Thalamus
A fibrous arch Egg-shaped
connecting the structure flanking
the third ventricle;
mammillary this is a major
bodies to the relay station
hippocampus; for both motor
and sensory
the fornix is fibers leaving and
part of the entering the brain
limbic system
Optic radiation
Splenium of Part of the visual
corpus pathway where
nerve fibers fan
callosum out to reach the
visual cortex in
Inferior horn the occipital lobe
of lateral
ventricle
TRANSVERSE SECTION OF BRAIN
HEAD CORONAL SECTION Body of corpus
AND NECK OF BRAIN callosum
NERVOUS
Anterior horn of
The brain is protected by three membranes lateral ventricle
called the meninges (which become inflamed
in meningitis). The tough dura mater layer is Fornix
the outermost covering, which surrounds the
brain and the spinal cord. Under the dura mater Third ventricle
is the cobweblike arachnoid mater layer. The
delicate pia mater is a thin membrane on Mammillary body
the surface of the brain. Between the pia mater
and the arachnoid mater there is a slim gap
—the subarachnoid space—which contains
cerebrospinal fluid (CSF). Mainly produced
by the choroid plexus in the brain’s lateral
ventricles, CSF flows through the third ventricle
into the fourth, where it can escape via small
apertures into the subarachnoid space.
VENTRICLES Anterior horn of lateral ventricle
OF THE BRAIN Part of the lateral ventricle located in
the frontal lobe
113
Inferior horn of lateral ventricle
Front part of the lateral ventricle, which HEAD AND NECK • NERVOUS
projects down into the temporal lobe
Caudate
Interventricular foramen nucleus
Connects the two lateral ventricles Septum
pellucidum
Body of lateral ventricle Thalamus
Roofed by the corpus Lentiform
callosum nucleus
Hypothalamus
Third ventricle
Cavity surrounded by the thalamusMENINGES SECTION
Cerebral aqueduct
Connects the third and fourth
ventricles, via the midbrain
Fourth ventricle
Cavity that lies between the pons and
the cerebellum
Median aperture of the fourth ventricle
Midline opening in the roof of the fourth
ventricle where cerebrospinal fluid can drain
Posterior horn of lateral ventricle
Part of the lateral ventricle that extends
into the occipital lobe
Falx cerebri
Pia mater
A thin membrane that is the innermost
of the meninges, lining the brain itself
Arachnoid mater
Middle layer of the meninges
Arachnoid granulation
Pocket of the subarachnoid space, where
cerebrospinal fluid flows back into the blood
Dura mater
Outer layer of the meninges; dura
mater is Latin for hard mother
Superior sagittal sinus
Skull
114
ANATOMY
HEAD AND NECK The 12 pairs of cranial nerves (the standard of cranial nerves emerge from the brain stem.
NERVOUS abbreviation for which is CN) emerge from the All the cranial nerves supply parts of the head
brain and brain stem, leaving through holes, or and neck, except the vagus nerve. This has
“foramina,” in the base of the skull. Some nerves branches in the neck, but then continues on to
are purely sensory, some just have motor supply organs in the thorax and right down in
functions, but most contain a mixture of motor the abdomen. Careful testing of cranial nerves,
and sensory fibers. A few also contain autonomic including tests of sight, eye and head movement,
nerve fibers. The olfactory nerve and the optic taste, and so on, can help doctors pinpoint
nerve attach to the brain itself. The other 10 pairs neurological problems in the head and neck.
Olfactory tracts Olfactory bulbs
Receive the olfactory
Optic nerve (CN II) nerves (CN1)
Oculomotor nerve (CN III) Pons
Emerges just above the pons of
Pyramid
the brain stem
Motor root of trigeminal
Trochlear nerve (CN IV) nerve (CN V)
Emerges from the back of the Small root containing the
midbrain, then runs forward to nerve fibers destined for
appear at the side of the pons the muscles of mastication
(chewing)
Abducent nerve (CN VI)
Emerges above the Sensory root of
trigeminal nerve (CN V)
pyramids of the medulla Contains sensory nerve
(see p.109) fibers that will be distributed
to the face, mouth, and
Facial nerve (CN VII) nose in the three branches
Emerges at the junction of the trigeminal nerve
of the pons and medulla,
Glossopharyngeal
at the side nerve (CN IX)
Emerges from the side
Vestibulocochlear of the medulla
nerve (CN VIII)
Vagus nerve (CN X)
Emerges at the junction of Exits the cranium via the
the pons and medulla jugular foramen, along
with the glossopharyngeal
Hypoglossal nerve (CN XII) and accessory nerves
Formed from a series of rootlets
Accessory nerve
emerging from the groove (CN XI)
between the olive and pyramid Formed by rootlets
emerging from the
of the medulla medulla and the upper
spinal cord
Olive
ORIGIN OF CRANIAL NERVES (UNDERSIDE OF BRAIN)
Auriculotemporal Ophthalmic nerve Greater auricular nerve 115
nerve A branch of the trigeminal nerve, supplying A branch of the second cervical
HEAD AND NECK • NERVOUS
Branch of the sensation to the upper part of the face nerve, supplying sensation to
mandibular division the skin of the back of the head CRANIAL NERVES IN
HEAD AND NECK (SIDE)
of the trigeminal
nerve, supplying Posterior
sensation to part of auricular nerve
the ear and temple A branch of the
facial nerve,
Temporal branch supplying the
of facial nerve occipital belly of
Supplies the occipitofrontalis
frontal belly of muscle
occipitofrontalis
and orbicularis
oculi muscles
Optic nerve
(CN II)
Carries sensory
information from
the retina of the eye
Zygomatic
branch of
facial nerve
Supplies orbicularis
oculi muscle
Infraorbital nerve
Branch of the
maxillary division of
the trigeminal
nerve, supplying
sensation over
the cheek
Buccal branch of Lingual nerve Trigeminal
facial nerve Branch of the mandibular nerve (CN V)
Supplies the division of the trigeminal Colored deep
muscles of nerve, supplying sensation orange on this
the upper lip illustration; splits
to the tongue into ophthalmic,
Mental nerve maxillary, and
Continuation of the Glossopharyngeal mandibular
nerve (CN IX) divisions
inferior alveolar
nerve, supplying Hypoglossal nerve Facial nerve
(CN XII) (CN VII)
sensation over Colored bright
the chin Vagus nerve (CN X) yellow on this
illustration
Inferior alveolar
nerve Cervical branch
of facial nerve
Branches of this Supplies platysma
nerve innervate the muscle in the neck
lower teeth, the Accessory nerve
gums, the lower lip, (CN XI)
and the chin
Marginal
mandibular branch
of facial nerve
Supplies muscles of the
lower lip and chin
116
ANATOMY
Sclera Iris Upper eyelid
HEAD AND NECK EXTERNAL EYE
NERVOUS
Plica semilunaris
EYE Eyelashes Pupil Lacrimal caruncle
Lacrimal papilla
The eyes are precious organs. They are well protected inside the eye sockets, or Frontal nerve Conjunctiva
bony orbits, of the skull. They are also protected by the eyelids, and bathed in Large branch of the
tears produced by the lacrimal glands. Each eyeball is only 1 in (2.5 cm) in Lower eyelid
diameter. The orbit provides an anchor for the muscles that move the eye, and ophthalmic nerve;
the rest of the space inside the orbit is largely filled up with fat. Holes and fissures splits into supraorbital
at the back of this bony cavern transmit nerves and blood vessels, including the
optic nerve, which carries sensory information from the retina to the brain. Other and supratrochlear
nerves supply the eye muscles and the lacrimal glands, and even continue on to branches
the face to supply sensation to the skin of the eyelids and forehead.
Superior oblique muscle Lateral rectus Lateral wall Supratrochlear nerve Supraorbital nerve
Rotates the eyeball downward Runs over the eyeball and Runs forward, out
muscle of orbit of the orbit, and turns
and outward, as well as Rotates the eyeball Formed here by the up, out of the orbit, to upward on the frontal
medially; the inferior oblique outward (abduction) zygomatic bone supply sensation to the bone to supply the
middle of the forehead upper eyelid
muscle under the eyeball
rotates it upward and inward Lacrimal nerve
Supplies skin over
Trochlea of Ciliary ganglion the upper eyelid
superior oblique Receives and lateral forehead
muscle parasympathetic Lacrimal
Trochlea is Greek for nerve fibers from the gland
pulley; the superior
oblique muscle runs oculomotor nerve
through this fibrous and sends them into
loop attached to the
frontal bone, which the eyeball via the
changes the muscle’s short ciliary nerves, to
supply the muscles of
trajectory
the iris and lens
Medial rectus
muscle Abducent nerve
Supplies the lateral
Rotates the eyeball
inward (adduction) rectus muscle
Superior rectus Nasociliary nerve
muscle Part of the
Rotates the eyeball ophthalmic nerve;
upward (elevation); the its branches supply
inferior rectus under sensation to the
the eyeball rotates it ethmoidal sinuses,
downward the nasal cavity,
(depression) and the eyeball
Medial wall of Ophthalmic nerve
orbit Branch of the
Formed here by trigeminal nerve;
the ethmoid bone supplies sensation to
Common annular the eyeball, the
tendon conjunctiva, and part
A ringlike tendon of the lining of the
anchored to the nose, as well as the
edges of the optic eyelids and forehead
canal and superior
orbital fissure, to Optic nerve
Carries sensory nerve
which the four fibers from the retina
rectus (straight)
muscles of the Superior orbital fissure MUSCLES OF THE EYE Oculomotor nerve Trochlear nerve NERVES OF THE ORBIT
Hole in the sphenoid bone (FROM ABOVE) Supplies all muscles Supplies the superior (FROM ABOVE)
eye attach that move the eye,
at the back of the orbit oblique muscle
except for the
superior oblique and
lateral rectus muscles
Conjunctiva Vitreous humor 117
Thin mucous membrane Means glassy fluid in Latin.
covering the front of the HEAD AND NECK • NERVOUS
eyeball, as well as the inner The main filling of the
eyeball, it is liquid in Lateral rectus
surfaces of the eyelids, the center but more muscle
but not the cornea gel-like at the edges
Choroid
Iris Sclera This layer is packed
From the Greek From the Greek for with blood vessels
hard; the tough, outer
for rainbow; coat of the eyeball Optic disc
contains smooth Retinal nerve fibers
muscle: circular create a doughnutlike
bulge where they
fibers constrict gather to form the
the pupil, while optic nerve
radial muscle
fibers dilate it
Cornea
Transparent
outer layer of
the front of the
eye; continuous
with the sclera
Pupil
Aqueous Optic nerve
humor Carries visual
information
Watery fluid from the retina
occupies the back to the brain
anterior and
Blind spot
posterior Where retinal nerve fibers
chambers of leave the back of the retina
the eye, either the eye has no sensory
side of the iris cells; the brain fills in the
missing information, so
Lens that we are not aware of the
Made up of tiny blind spot in each eye
long, transparent
cells called lens
fibers; tends to
become less
clear in old age
Suspensory
ligament
Attaches the lens
to the ciliary body
Ciliary body Medial rectus Retina
Contains smooth muscle muscle Inner, sensory lining of
the eyeball; forms as an
fibers that pull to alter outgrowth of the brain
the shape of the lens in itself during embryological
development
order to focus
HORIZONTAL SECTION THROUGH THE EYEBALL
118 Incus Posterior semicircular canal
The middle ossicle in the
ANATOMY The semicircular canals are each
chain, the incus is also less than 3/4 in (2 cm) in length,
Temporal bone named for its shape, and
Forms part of with a diameter of less than 1/32 in
means anvil in Latin (1 mm); this canal is positioned
the side wall and vertically
base of the skull; Malleus
This mallet-shaped ossicle
houses the attaches to the back of the
workings of tympanic membrane and
the ear connects to the incus
Auricle
Made of elastic
fibrocartilage
covered with skin
External acoustic meatus
The outer third of this canal is
made of cartilage, while the inner
two-thirds is a channel within the
temporal bone; the meatus is lined
with thin skin, which continues on
to the eardrum
EXTERNAL EAR Oval window
Where the stapes
attaches to the base of
the cochlea, transmitting
its vibrations to the fluid
inside the cochlea
HEAD Tympanic membrane
AND NECK The eardrum vibrates as
NERVOUS sound waves buffet it; the
ossicles (the malleus, incus,
and stapes) carry those
vibrations through the
middle ear to the inner ear
EAR Stapes
The last link in the
The ear can be divided up into external, middle, and internal parts.
The external ear includes the auricle on the outside of the head, and chain of ossicles;
the external acoustic meatus—the canal that leads to the eardrum, stapes means
or tympanic membrane. The middle ear is an air space inside the stirrup in Latin
temporal bone. It contains the ossicles (ear bones) and is linked to
the pharynx by the pharyngotympanic, or eustachian, tube. Minute MIDDLE AND INNER EAR
hair cells inside the inner ear convert vibrations in the fluid within
the cochlea into an electrical nerve impulse. Similar hair cells in the
vestibular apparatus (the semicircular canals, utricle, and saccule)
convert mechanical stimuli, produced by motions of the head, into
nerve impulses (see pp.316–317). The sensory nerves leaving the inner
ear join to form the vestibulocochlear nerve.
Lateral semicircular canal Anterior semicircular canal Helix 119
This is positioned horizontally Positioned vertically, but at right The outer rim
angles to the plane of the posterior of the auricle HEAD AND NECK • NERVOUS
semicircular canal
Antihelix
Vestibular nerve A curved
Carries sensory information prominence,
from the vestibular apparatus— parallel to the helix
including the semicircular canals
External acoustic
Cochlear nerve meatus
Conveys sensory
information about Tragus
sound from the This little flap
cochlea overlaps the external
acoustic meatus
Concha Intertragic notch
This hollow is
named after the Lobule
Greek for shell
Antitragus AURICLE
A small tubercle
opposite the tragus
Section cut from cochlea
From top to bottom shows
vestibular canal, cochlear
duct, and tympanic canal
Vestibulocochlear nerve
The vestibular nerve and the
cochlear nerve join to form
the vestibulocochlear nerve
Cochlea Tympanic membrane
Not surprisingly, As seen with an otoscope,
cochlea means a healthy eardrum has a
snail in Latin pearly, almost translucent
appearance
Vestibule
Contains the utricle Lateral process
and sacule, organs of malleus
of balance
Handle of
Round window malleus
Vibrations can travel in the
fluid inside the cochlea, all the Cone of light
way up to its apex and back Light is reflected
down to the round window in the front, lower
quadrant of the
Pharyngotympanic tube eardrum
Passage connecting the middle ear
to the back of the throat, and EARDRUM
allowing air pressure either side of
the eardrum to be equalized
120
ANATOMY
Trigeminal nerve Facial nerve First cervical
(CN V) (CN VII) nerve (C1)
The very first spinal
Glossopharyngeal nerve; its branches
nerve (CN IX) supply some muscles
in the upper neck
Supplies sensation
to the back of the Second cervical
nerve (C2)
tongue and to Along with C3 and C4, this
the pharynx nerve supplies sensation
to the skin of the neck as
Hypoglossal well as supplying a range
nerve (CN XII) of muscles in the neck
Supplies the Third cervical nerve (C3)
muscles of
the tongue Accessory nerve
(CN XI)
Vagus nerve Originates outside the
(CN X) skull but enters it and then
comes back out; part of
Supplies muscles it joins the vagus, the
of the pharynx remaining fibers continue
and larynx, and into the neck to supply
trapezius and sterno-
continues down to cleidomastoid muscles
supply organs in
the thorax and Fourth cervical
abdomen nerve (C4)
Fifth cervical nerve (C5)
Together with C6, C7, C8
and T1, part of this nerve
will form the brachial plexus
—the network of nerves
supplying the arm
Sixth cervical
nerve (C6)
Seventh cervical
nerve (C7)
Eighth cervical
nerve (C8)
First thoracic
nerve (T1)
NERVES OF THE NECK (SIDE)
121
HEAD AND NECK • NERVOUS
HEAD AND NECK The last four cranial nerves all appear in the neck. The glossopharyngeal nerve supplies
NERVOUS the parotid gland and the back of the tongue, then runs down to the pharynx. The vagus
nerve is sandwiched between the common carotid artery and the internal jugular vein,
and it gives branches to the pharynx and larynx before continuing down into the thorax.
The accessory nerve supplies the sternocleidomastoid and trapezius muscles in the neck,
while the last cranial nerve, the hypoglossal, dips down below the mandible, then curves
back up to supply the muscles of the tongue. We can also see spinal nerves in the neck.
The upper four cervical nerves supply neck muscles and skin, while the lower four
contribute to the brachial plexus and are destined for the arm.
Sympathetic Larynx
trunk
Left common
Right common carotid artery
carotid artery The pulsation of
this artery is easy
Right internal to feel in the neck
jugular vein
Sternocleidomastoid
muscle
Left internal
jugular vein
Right vagus Cervical nerves
nerve
Body of cervical
Right phrenic vertebra
nerve
LEFT
Spinal cord SIDE OF
BODY
RIGHT
SIDE OF Trapezius
muscle
BODY
Spinal process
of cervical
vertebra
TRANSVERSE SECTION OF THE NECK
122 Olfactory SAGITTAL SECTION
nerves
ANATOMY
Superior meatus
Cribriform plate of The posterior ethmoid
ethmoid bone air sinuses open into
this space under the
Forms the long, narrow roof of superior concha (named
the nasal cavity; the olfactory after the Latin for shell)
nerves carrying the sense of
smell pass up through tiny Cut edge of
holes in this thin plate of superior concha
bone, into the cranial cavity
Middle meatus
Frontal sinus The frontal sinus, maxillary
One of the paranasal air sinus, and the rest of the
sinuses—spaces in the bones ethmoid air cells open into
of the skull that drain into the the nasal cavity here,
nasal cavity; they become beneath the middle concha
inflamed in sinusitis Cut edge of
middle concha
Atrium
Vestibule Sphenoidal sinus
Inside the sphenoid bone;
one of the paranasal air sinuses
Inferior meatus
The nasolacrimal duct—
draining tears from the inner
corner of the eye—opens into
the nasal cavity here;
that is why your nose tends
to run when you cry
Cut edge of
inferior concha
Nostril Nasopharynx
Uppermost part of the
Hard palate pharynx, behind the
Forms the nasal cavity—which
floor of ends level with the back
the nasal of the hard palate—and
cavity above the oropharynx
Oropharynx
The part of the pharynx
behind the cavity of the
mouth or oral cavity
Epiglottis
Uppermost cartilage
of the larynx
Laryngopharynx
Lower part of the
pharynx, behind
the larynx
False vocal cord Cricoid
Also known as the cartilage
vestibular cord Trachea
Thyroid
cartilage
Vocal cord
123
HEAD AND NECK • RESPIRATORY
Ethmoid Frontal
sinus sinus
HEAD AND NECK
RESPIRATORY
When we take a breath, air is pulled in through our nostrils, into the
nasal cavities. Here the air is cleaned, warmed, and moistened before
its onward journey. The nasal cavities are divided by the thin partition
of the nasal septum, which is composed of plates of cartilage and
bone. The lateral walls of the nasal cavity are more elaborate, with
bony curls (conchae) that increase the surface area over which the air
flows. The nasal cavity is lined with mucosa, which produces mucus.
This often undervalued substance does an important job of trapping
particles and moistening the air. The nasal sinuses, also lined with
mucosa, open via tiny orifices into the nasal cavity. Below and in front
of the pharynx is the larynx—the organ of speech. The way that air
passes through this can be modulated to produce sound.
Hyoid bone Epiglottis
Elastic piece of cartilage named after
the Greek for upon the tongue; it sits
behind the tongue, and helps protect
the airway during swallowing
Crycothyroid Thyroid X-RAY OF HEAD Nasal Nasal Maxillary sinus
membrane prominence SHOWING SINUSES cavity septum
Forms the “Adam’s
LARYNX apple” at the front of
the neck, and is more
prominent in men
than in women; the
vocal cords attach to
its inner surface
Arytenoid cartilage
“Funnel-shaped” in
Greek; there is a
mobile joint between
this small pyramidal
cartilage and the
cricoid cartilage;
small muscles attach
to the arytenoid,
which works as a lever
to open and close
the vocal cords
False vocal cord
Vocal ligament
or cord
Thyroid cartilage
The word thyroid
means shield shaped
in Greek
Cricoid cartilage
Shaped like a signet
ring; the word cricoid
comes from the Greek
for ring shaped
First tracheal
cartilage
124
ANATOMY
Superficial Posterior auricular
temporal artery artery
Supplies the scalp Supplies an area
over the side of the around the ear
head Occipital artery
Supplies the scalp
Maxillary artery on the back of the
Supplies the maxilla, head
mandible, palate, External carotid
nose, and teeth artery
Branches of this
Angular artery artery supply the
The continuation of larynx, thyroid gland,
the facial artery, lying mouth, tongue,
near the inner angle nasal cavity, face,
mandible, maxillae,
of the eye teeth, and scalp
Infraorbital artery Internal carotid
Emerges through the artery
infraorbital foramen
Vertebral artery
just under the orbit
Common
Buccal artery carotid artery
Lies to the side of
Superior labial the trachea in the
artery neck, where its
pulse may be felt
Branches from the
facial artery to supply EXTERNAL ARTERIES OF THE HEAD
the upper lip
Inferior labial
artery
Branches from the
facial artery to supply
the lower lip
Mental artery
Submental artery
A branch of the
facial artery that runs
on the underside
of the chin
Facial artery
Wraps under the
lower border of the
mandible—where its
pulse can be felt—and
runs up to supply
the face
Superior thyroid
artery
Supplies the thyroid
gland and muscles in
the front of the neck
125
HEAD AND NECK • CARDIOVASCULAR
Angular vein Superficial
temporal vein
Infraorbital vein Drains a network
of veins in the
Pterygoid venous scalp and ends
network by joining the
maxillary vein
A network of veins to form the
lying under the ramus retromandibular
vein
of the mandible
Posterior
Maxillary vein auricular vein
Drains the pterygoid Drains the scalp
behind the
venous network ear; joins the
retromandibular
Superior labial vein vein to form
Drains from the upper the external
lip, into the facial vein jugular vein
Inferior labial vein Occipital vein
Drains the lower lip Drains the back
of the scalp and
Mental vein runs deep to join
Submental vein other veins
Facial vein Retromandibular
vein
Superior thyroid Travels down
vein behind the
mandible, through
the parotid gland
alongside the
external carotid
artery
External jugular
vein
Drains the face
and scalp
Internal jugular
vein
The largest vein in
the neck, lies close
to the common
carotid artery
EXTERNAL VEINS OF THE HEAD
HEAD AND NECK The main vessels supplying oxygenated blood to the head and neck are the common
CARDIOVASCULAR carotid and vertebral arteries. The vertebral artery runs up through holes in the cervical
vertebrae and eventually enters the skull through the foramen magnum. The common
carotid artery runs up the neck and divides into two—the internal carotid artery supplies
the brain, and the external carotid artery gives rise to a profusion of branches, some of
which supply the thyroid gland, the mouth, tongue, and nasal cavity. Veins of the head
and neck come together like river tributaries, draining into the large internal jugular vein,
behind the sternocleidomastoid muscle, and into the subclavian vein, low in the neck.
126 Anterior Middle cerebral
cerebral artery artery
ANATOMY Supplies anterior Provides branches
to the cortex of
(front) parts of the frontal,
the brain parietal, and
temporal lobes
Ophthalmic artery of the brain
Runs through the optic
Cavernous part
canal with the optic of the internal
nerve to supply eye, carotid artery
Passes into the
eyelids, nose, and carotid canal and
forehead emerges inside
the skull, traveling
The brain has a rich blood supply, through the
which arrives via the internal carotid cavernous sinus
and vertebral arteries. The vertebral
arteries join together to form the Posterior
basilar artery. The internal carotid communicating
arteries and basilar artery join on artery
the undersurface of the brain to
form the Circle of Willis. From there, Posterior
three pairs of cerebral arteries make cerebral artery
their way into the brain. The veins
of the brain and the skull drain into Basilar artery
venous sinuses, which are enclosed
within the dura mater (the Internal carotid
outermost layer of the meninges) artery
and form grooves on the inner
surface of the skull. The sinuses External carotid
join up and eventually drain out artery
of the base of the skull, into the
internal jugular vein. Vertebral
arteries
ARTERIES AROUND THE BRAIN Travel up through
the foramina
HEAD AND NECK in the cervical
CARDIOVASCULAR vertebrae, and
enter the skull
Circle of Willis Middle cerebral through the
artery foramen magnum
Posterior Common
communicating carotid artery
artery Anterior cerebral artery
Posterior Anterior communicating
cerebral artery artery
Pontine arteries Internal carotid artery
Branch from the basilar
artery to supply the pons Superior cerebellar
artery
Anterior spinal artery Highest of three pairs
Supplies the medulla of arteries supplying the
and spinal cord cerebellum of the brain
LOCATION CIRCLE OF WILLIS Basilar artery
OF CIRCLE Carries blood from
OF WILLIS vertebral arteries to the
Circle of Willis and
supplies the midbrain
Vertebral artery
Joins the other vertebral
artery to form the
basilar artery
Posterior inferior
cerebellar artery
Supplies the cerebellum and
the choroid plexus of the
fourth ventricle in the brain
Cavernous sinus 127
A network of veins lying
on the base of the skull HEAD AND NECK • CARDIOVASCULAR
Superior Superior sagittal sinus
ophthalmic vein Runs in the upper edge
of the falx cerebri
Drains into the
cavernous sinus Inferior sagittal sinus
Lies in the lower edge
Inferior of the falx cerebri, a fold of
ophthalmic vein dura mater that lies betwen the
Connects with the cerebral hemispheres
pterygoid venous plexus
through the inferior Great cerebral vein
Drains out of the brain
orbital fissure into the straight sinus
Pterygoid venous Straight sinus
plexus Drains the inferior sagittal sinus
and the great cerebral vein
Confluence of the sinuses
Lies to one side of the internal
occipital protuberance
Sigmoid sinus
Gets its name from the Greek
for S-shaped
Internal
jugular vein
VEINS AROUND THE BRAIN
Sphenoparietal sinus Cavernous sinus
Marginal sinus Inferior petrosal sinus
Confluence of sinuses Connects the cavernous sinus
Superior sagittal sinus to the internal jugular vein
Superior petrosal sinus
Connects the cavernous
to the transverse sinus
Sigmoid sinus
Forms the continuation of the
transverse sinus and passes
through the jugular foramen to
become the internal jugular vein
Transverse sinus
Lies in the margin of the
cerebellar tentorium, separating
the cerebral hemispheres from
the cerebellum
DURAL VENOUS SINUSES
128 Occipital nodes
Drain the scalp of
ANATOMY the back of the head
LYMPH NODES OF HEAD Mastoid nodes
Also called the
Parotid nodes retroauricular nodes;
Also called the drain the scalp above
preauricular nodes; and behind the ear
drain the forehead and Jugulodigastric node
temporal region around One of the upper deep
and above the ear cervical nodes, lying just
behind the angle of the
Buccal node jaw; receives lymph
from the tonsil
Submandibular nodes
Around and often within Superficial cervical
nodes
the submandibular Lie along the external
salivary gland; they drain jugular vein
the nose, cheeks, and Internal jugular vein
upper lip
Paratracheal nodes
Mandibular node Receive lymph from
Submental nodes the larynx, trachea,
Drain the lower lip, and esophagus, and
floor of the mouth, and drain to deep nodes
tip of the tongue;
lymph then passes to
the submandibular and
jugulodigastric nodes
Prelaryngeal nodes
Infrahyoid nodes
Jugulo-omohyoid node
One of the lower deep cervical
lymph nodes; this receives
lymph from the tongue
Pretracheal nodes
Drain the trachea and
thyroid gland
HEAD AND NECK
LYMPHATIC AND IMMUNE
129
HEAD AND NECK • LYMPHATIC AND IMMUNE
LOCATION OF TONSILS
Nasal cavity Pharyngeal tonsil
This lymphoid tissue is
Palatine tonsil prominent in children
Lies under the and referred to as
the adenoid
mucous membrane
or mucosa of the Opening of
pharyngotympanic
oropharynx; the two (Eustachian) tube
are often just called
Soft palate
the tonsils
Pharynx
Tongue Runs from the area
behind the nasal cavity
Lingual tonsil to behind the larynx
Lymphoid tissue and consists of three
under the mucosa areas, named, from
top to bottom:
of the back of nasopharynx,
the tongue oropharynx, and
laryngopharynx
Epiglottis
Larynx
A ring of lymph nodes lies close to the skin where sternocleidomastoid muscle. Lymph from all other
the head meets the neck, from the occipital nodes nodes passes to these deep ones, then into the
(against the skull at the back) to the submandibular jugular lymphatic trunk before draining back into
and submental nodes (which are tucked under veins in the base of the neck. Lymphoid tissue, in
the jaw). Superficial nodes lie along the sides and the form of the palatine, pharyngeal, and lingual
front of the neck, and deep nodes are clustered tonsils, forms a protective ring around the upper
around the internal jugular vein, under cover of parts of the respiratory and digestive tracts.
130
ANATOMY
Tongue SAGITTAL SECTION
Manipulates
Hard palate
food in the The mucosa here is firmly
mouth, bears bound to the periosteum
taste buds, and (membrane covering the
forms sounds bone), ensuring that this
lining is not moved and
Upper lip damaged during chewing
Upper incisor Oral cavity
Lower incisor Parotid gland
Lower lip Nasopharynx
Sublingual Submandibular Oropharynx
gland gland
Epiglottis
Geniohyoid Hyoid bone Helps close the
This muscle Larynx opening to the larynx
raises the during swallowing
hyoid during
swallowing Laryngopharynx
Lowest part of the
Submandibular pharynx; lies behind
duct the larynx, and
continues below into
Mylohyoid the esophagus
Sheet of muscle that forms Esophagus
The pharynx becomes
the floor of the mouth; the esophagus at the
contracts to raise the hyoid level of the sixth
bone and push the tongue cervical vertebra
up against the roof of the
mouth during swallowing
Foramen cecum Pharyngeal part 131
This small, blind of tongue
Lymphoid tissue HEAD AND NECK • DIGESTIVE
hole at the back of underlies the
the tongue is a mucosa here, HEAD
forming the AND NECK
remnant of where lingual tonsil DIGESTIVE
the thyroid gland
started to develop in Sulcus terminalis The mouth is the first part of the digestive tract, and it is here that the
the embryo, before Border between the processes of mechanical and chemical digestion get underway. Your
it dropped down pharyngeal and oral teeth grind each mouthful, and you have three pairs of major salivary
parts of the tongue, glands—parotid, submandibular, and sublingual—that secrete saliva
into the neck lying in the oropharynx through ducts into the mouth. Saliva contains digestive enzymes that
and oral cavity begin to chemically break down the food in your mouth. The tongue
Vallate papillae respectively manipulates the food, and also has taste buds that allow you to
There are around a quickly make the important distinction between delicious food and
dozen of these large Foliate papillae potentially harmful toxins. As you swallow, the tongue pushes up
papillae at the back Leaf-shaped against the hard palate, the soft palate seals off the airway, and the
of the tongue; each papillae that form muscular tube of the pharynx contracts in a wave to push the ball of
one is surrounded a series of ridges food down into the esophagus, ready for the next stage of its journey.
by a circular furrow on each side of the
back of the tongue
that contains
taste buds Oral part of
the tongue
Fungiform papilla
Literally means Filiform papilla
Tiny, hair-shaped
mushroom-shaped; papillae that give
these are scattered the tongue a
over the tongue like velvety texture
mushrooms across
the lawn of filiform
papillae; fungiform
papillae also bear
taste buds
TONGUE
Lateral incisor Central incisor Eruption of teeth
Around 8 years Around 7 years The ages given here are the
approximate times of eruption
Canine First premolar of the permanent teeth.
Around 11 years Around 9 years
First molar Second premolar
Around 6 years Around 10 years
Second molar Crown Enamel
Around 12 years Neck The hardest tissue
in the human body
Third molar Root
From 17 to 21 years Dentine
(although these “wisdom Hard tissue forming
the bulk of the tooth
teeth” may stay,
unerupted, in the jaw, or Pulp cavity
Connective tissue
may even be absent) containing nerves
and blood vessels
Gingivae
The gums—connective Cementum
tissue containing blood This bonelike tissue covers
the roots of the tooth
vessels, covered
with mucosa Periodontal ligament
Collagen fibers bind the
TEETH tooth roots to the bone
of the socket
132 Hypothalamus
Pituitary gland
ANATOMY The name of this gland
commemorates a historical
ENDOCRINE misapprehension: it comes
SYSTEM from the Latin for mucus
or phlegm, as it used to be
The insides of our bodies are regulated by the thought—wrongly—that the
autonomic nervous and endocrine systems. There pituitary gland secreted
is overlap between these two systems, and their nasal mucus
functions are integrated and controlled within the
hypothalamus of the brain. The pituitary gland has Pineal gland SIDE
two lobes; its posterior lobe develops as a direct This tiny gland is about 5/16 in
extension of the hypothalamus (see pp.386–87).
Both lobes of the pituitary gland secrete hormones (8 mm) long, and shaped a
into the bloodstream, in response to nerve signals bit like a pine nut; it has links
or blood-borne releasing factors from the to the visual pathway, and is
hypothalamus. Many of the pituitary hormones
act on other endocrine glands, including the involved in regulating
thyroid gland in the neck, the suprarenal glands circadian rhythms—the daily
on top of the kidneys, and the ovaries or testes.
sleep–wake cycle
Pituitary gland tissue
Some hormone-secreting cells in the
anterior pituitary appear stained red in
this image, including those that produce
growth hormone, others are stained blue.
Thyroid blood supply
This resin cast of the thyroid gland
shows capillaries wrapped around
secretory cells (rounded), which release
hormones into the bloodstream.
Thyroid gland Left lobe of thyroid gland
The name of this gland Isthmus of thyroid gland
comes from the term for
shield shaped in Greek (as
does the name of the thyroid
cartilage of the larynx, which
is—coincidentally—a similar
shape); a more apt description
might be butterfly shaped
Right superior
parathyroid gland
Four pea-sized glands sit
at the back of the thyroid
Right lobe of
thyroid gland
Right inferior
parathyroid gland
134
ANATOMY
Cerebral Cingulate
cortex gyrus
Eye Frontal
sinus
Nasal
septum Meninges
Maxillary
sinus Nasal
cavity
Tongue Teeth
Soft
1
palate
HEAD AND LEVELS OF SCANS
NECK MRI Tongue
1
The discovery of X-rays at the end of the 19th century Epiglottis
suddenly created the possibility of looking inside 3 Larynx
the human body—without having to physically cut 4
it open. Medical imaging is now an important
diagnostic tool, as well as being used for the study 5
of normal anatomy and physiology. In computed
tomography (CT), X-rays are used to produce virtual 2
sections or slices through the body. Another form
of sectional imaging, using magnetic fields rather 2
than X-rays to create images, is magnetic resonance
imaging (MRI), as shown here. MRI is very useful for
looking in detail at soft tissue, for instance, muscle,
tendons, and the brain. Also seen clearly in these
sections are the eyes (1 and 3), the tongue (1 and 2),
the larynx, vertebrae, and spinal cord (2 and 5).
135
HEAD AND NECK • MRI
Skull Cerebral Skull
Corpus cortex Third
callosum Lateral ventricle
Optic
Thalamus ventricle nerve
Hypothalamus Nose
Eye
Pons Outer ear
Cerebellum 3
Teeth
Medulla Meninges
oblongata Cerebellum
Spinal cord 4
Vertebra
Intervertebral
disc
Spinous process Trapezius
Spinal cord Thyroid
cartilage
Vertebra
Pharynx
5
136 T1 (first thoracic) vertebra
Clavicle
ANATOMY
First rib
Smaller and more curved than
all the other ribs; the thoracic
inlet is formed by the first rib
on each side, together with
the manubrium sterni and the
body of the T1 vertebra
Scapula
Second costal cartilage
The upper seven ribs are true
ribs, and all attach directly
to the sternum via
costal cartilages
Third rib
Fourth rib
Fifth rib
Sixth rib
Seventh rib
Eighth to tenth ribs
The costal cartilages
of these ribs each
attach to the costal
cartilage above
Eleventh and twelfth ribs
These are also called floating
ribs because they do not
attach to any others
Transverse process of T1 137
Each rib articulates with
the transverse processes of the THORAX • SKELETAL
corresponding thoracic vertebra
Head of first rib
The heads of the ribs articulate
with the bodies of vertebrae
Manubrium sterni
The sternum is shaped
like a dagger or short
sword; manubrium
means handle or hilt
in Latin
Manubriosternal joint
Body of sternum
Sternum comes
from the Greek for
breastbone
Xiphisternal joint
ANTERIOR Xiphoid process
(FRONT) The tip of the sternum
takes its name from the
Greek word for sword
THORAX
SKELETAL
The skeleton of the thorax plays several extremely important roles.
It not only acts as an anchor for muscle attachment, but during
breathing the ribs also move up and out to increase the volume
inside the thoracic cavity and draw air into the lungs. It also forms
a protective cage around the precious organs inside: the heart and
lungs. The bony thorax includes the 12 thoracic vertebrae, 12 pairs
of ribs and costal cartilages, and the breastbone, or sternum. The
upper seven ribs all articulate with the sternum via their costal cartilages.
The eighth to the tenth costal cartilages each join to the cartilage above,
creating the sweeping curve of the ribcage below the sternum on
each side. The eleventh and twelfth ribs are short and do not join any
other ribs—they are sometimes referred to as free or floating ribs.
138
ANATOMY
First rib
Third rib
Fifth rib
Seventh rib
Ninth rib
Tenth rib
Eleventh rib
With your fingers tracing
down the edge of the
ribcage, you may be able
to feel the end of the
eleventh rib in your side
Twelfth rib
The twelfth rib is even
shorter than the eleventh,
and tucked underneath
muscles, so it cannot
be felt. Unlike most ribs,
the twelfth has no
costal groove
C7 (seventh cervical 139
vertebra)
THORAX • SKELETAL
Transverse process of T1
Costal groove THORAX
SKELETAL
POSTERIOR (BACK)
There are cartilaginous joints between the
vertebrae at the back of the thorax, and between
the parts of the sternum at the front. The joints
between the ribs and the vertebrae at the back are
synovial, allowing the ribs to move during breathing.
When taking a breath, the anterior (front) ends of
the upper ribs, along with the sternum, lift up and
forward to increase the chest’s front-to-back
diameter, while the lower ribs move up and out,
increasing the side-to-side diameter. Most ribs
have a costal groove marking the lower border,
on the inner surface, where nerves and vessels of
the thoracic wall lie.
Cervical spine C1 Intervertebral 140
(Seven vertebrae make up the spine in the neck) (atlas) foramen
These are the ANATOMY
C2 holes between
(axis) adjacent THORAX
vertebrae through SKELETAL
C3 which spinal
C4 nerves emerge SPINE
C5
C6 Superior articular The spine, or vertebral column, occupies a central position in the
C7 process skeleton, and plays several extremely important roles: it supports
T1 the trunk, encloses and protects the spinal cord, provides sites for
T2 Cervical muscle attachment, and contains blood-forming bone marrow.
T3 curvature The entire vertebral column is about 28 in (70 cm) long in men,
A dorsally and 24 in (60 cm) long in women. About a quarter of this length
T4 is made up by the cartilaginous intervertebral disks between the
concave vertebrae. The number of vertebrae varies from 32 to 35, mostly
T5 curvature, or due to variation in the number of small vertebrae that make up
lordosis (from a the coccyx. Although there is a general pattern for a vertebra—
T6 Greek word most possess a body, a neural arch, and spinous and transverse
meaning bent processes—there are recognizable features that mark out the
T7 vertebrae of each section of the spine.
backward)
T8 Demifacet Superior Anterior arch
Intervertebral disk for rib joint The atlas has no body,
T9 Weight-bearing articular facet but it has an anterior
cartilaginous joint Articulates with arch that forms a joint
T10 composed of an outer the condyle of the with the dens of
annulus fibrosus occipital bone, on the axis
(fibrous ring) and an the base of the skull
inner nucleus pulposus Transverse foramen
(pulpy nucleus) Lateral mass ATLAS (C1)
Vertebral foramen Posterior arch
Thoracic spine Thoracic curvature
(Twelve vertebrae, providing attachment for twelve pairs of ribs) This dorsally convex type Superior Dens (odontoid peg)
of curvature is technically articular This projection sticks
known as a kyphosis, from up to articulate with
facet the atlas
the Greek for crooked
Body Transverse process
Vertebral Transverse foramen
foramen
Spinous process
AXIS (C2)
Body
Transverse Lamina Made of cancellous bone
foramen containing blood-making
CERVICAL bone marrow
The vertebral Transverse process
artery passes For neck muscle attachment
through here
Superior articular facet
Vertebral
foramen Spinous process
Large compared Tends to be small and
with the size forked; for the attachment
of the body; of back muscles
contains the
spinal cord
T11 Transverse process Body
T12 Forms a joint with the Thoracic vertebrae have
heart-shaped bodies
L1 ribs on each side
L2 Vertebral foramen
L3 Lumbar Zygapophyseal THORACIC Superior articular
L4 curvature (facet) joint facet
L5 Synovial joints between
Appears the adjacent articular Lamina
ANTERIOR about a year processes allow variable Spinous process
(FRONT) degrees of movement Long and sloping in
after birth, in different sections of the thoracic spine
when an the spine; in disk
degeneration, these joints Body
infant starts end up bearing more Vertebral bodies are
to walk weight and may be a larger at lower spinal
source of back pain levels—they have
S1 progressively more
S2 Vertebral weight to bear; bodies
foramen of lumbar vertebrae
S3 are kidney-shaped,
Lumbar spine S4 Pedicle and large compared
(Five vertebrae) S5 with the size of the
co1 Superior vertebral foramen
co2 Inferior articular
co3 articular Spinous process
process facet Large and square in
the lumbar spine
Lateral part Transverse Lamina
Formed from Facet for
fused lateral process LUMBAR coccyx
Long and thin
parts of the
sacral segments;
articulates with
the pelvis at the
sacroiliac joint
Sacrum Sacral Body
(Five fused vertebrae) curvature Five vertebrae
fuse during SACRUM
development
141
to form the
sacrum THORAX • SKELETAL
Anterior sacral
foramen
Anterior branches of
sacral spinal nerves
pass through these
holes; posterior
branches emerge
through the
posterior foramina
Coccyx Coccygeal cornu Facet for apex
(Three to five vertebrae) Articulates with of sacrum
sacral cornu
COCCYX
SIDE
142
ANATOMY
Sternocleidomastoid
Clavicle
Pectoralis major
This great pectoral
muscle attaches
to the clavicle, the
sternum, and
the ribs; it inserts
into the upper
part of the
humerus. It can
pull the ribs up
and out during
deep breathing
Serratus anterior Rectus abdominis
The digitations This pair of straight
muscles, crossed by
(fingerlike parts) of this fibrous bands, attaches
muscle attach to the to the lower margin of
the sternum and ribcage
upper eight or nine ribs
External oblique
ANTERIOR (FRONT) Outermost of the three muscle
SUPERFICIAL layers in the side of the abdomen.
It attaches to the lower ribs and,
along with other abdominal
muscles, is drafted during forced
expiration, compressing the
abdomen and, thus, pushing
the diaphragm up, helping force
air out of the lungs
Omohyoid 143
Scalenus anterior
THORAX • MUSCULAR
Subclavius
Costal cartilage
Pectoralis minor
Sternum
Rib
Intercostal muscles
Three layers of muscle
occupy the intercostal
spaces between the ribs:
external, internal, and
innermost intercostal
muscles
External intercostal
muscle
Internal intercostal
muscle
The muscle fibers of
this middle layer run
diagonally in the
opposite direction to
those of the external
intercostal muscle
THORAX
MUSCULAR
Rectus sheath The walls of the thorax are filled in, between the ribs, by the intercostal
Internal oblique muscles. There are three layers of these muscles, and the muscle
fibers of each layer lie in different directions. The main muscle for
ANTERIOR breathing is the diaphragm. Although the intercostal muscles are
(FRONT) DEEP also active during respiration, their main job seems to be to prevent
the spaces between the ribs from being “sucked in.” Other muscles
seen here may also be recruited to help with deep breathing. The
sternocleidomastoid and scalene muscles in the neck can help by
pulling the sternum and upper ribs upward. The pectoral muscles
can also pull the ribs up and out, if the arm is held in a fixed position.
144
ANATOMY
Rhomboid minor
The four-sided rhomboid
muscles act to pull the
scapulae toward
the midline
Spine of scapula
Rhomboid
major
Infraspinatus
One of the rotator
cuff, or short
scapular muscles
Teres minor
Teres major
Vertebral (medial)
border of scapula
Inferior angle of
scapula
Spinalis
The innermost (most
medial) part of the
erector spinae; it
attaches to the
spinous processes of
the vertebrae
Erector spinae
muscle group
Rib
Serratus posterior inferior
This muscle attaches from the
lower thoracic and upper
lumbar vertebrae to the lower
four ribs; there is also a serratus
posterior superior muscle,
tucked under the rhomboids
Intercostal muscle
POSTERIOR
(BACK) DEEP
145
THORAX • MUSCULAR
Trapezius
Infraspinatus
Teres major
This tapering muscle
takes its name from the
Latin for rounded off
Latissimus dorsi
This huge muscle sweeps
up from the lower part
of the back to attach to
the humerus
THORAX
MUSCULAR
External oblique The superficial muscles of the back include two large, triangular-
shaped muscles—the massive latissimus dorsi and trapezius muscles.
POSTERIOR Although latissimus dorsi is called into action during forced expiration,
(BACK) SUPERFICIAL squeezing the lower chest to expel air, it is really a climbing muscle:
if you hang by your arms, it is largely the powerful latissimus that can
allow you to pull your body weight up. Underneath those superficial
muscles are the deeper extensor muscles of the spine, which can
be felt as a distinct ridge on each side of the spine, especially in the
lumbar (lower back) region. The most bulky of these muscles are
collectively known as erector spinae, and play a vital role doing just
that—keeping the spine erect, or extending a flexed spine.
146
ANATOMY
Anterior longitudinal
ligament
Runs down and binds together
the bodies of the vertebrae
Internal intercostal
membrane
The internal intercostal muscles
give way to a membrane
at the back of the thorax
Central tendon of diaphragm
Flat tendon pierced by the
inferior vena cava
Muscular part of diaphragm
Supplied by the phrenic nerves
Right crus of diaphragm
The crura—literally, the “legs”—of
the diaphragm attach to the
bodies of the upper three
lumbar vertebrae
Middle scalene 147
Anterior scalene
THORAX • MUSCULAR
Longus colli
External intercostal muscle
These muscles are replaced
by a membrane around the
front of the thorax. (Seen
here after removal of internal
intercostal membrane)
Internal intercostal muscle
The intercostal muscles are
supplied by intercostal nerves
Left crus THORAX
of diaphragm MUSCULAR
BACK WALL The diaphragm, which divides the thorax and abdomen, is the main
OF THORACIC muscle of respiration. It attaches to the spine and to deep muscles in
CAVITY the back, around the margins of the rib cage, and to the sternum at the
front. Its muscle fibers radiate out from a central, flat tendon to these
attachments. The diaphragm contracts and flattens during inspiration,
increasing the volume inside the chest cavity, and pulling air into the
lungs; during expiration, it relaxes back into a domed shape. The
intercostal muscles and diaphragm are “voluntary” muscle, and you
can consciously control your breathing. But most of the time you don’t
have to think about breathing, since they work to a rhythm set by the
brain stem, producing about 12 to 20 breaths per minute in an adult.
148
ANATOMY
Vagus nerve
The tenth cranial nerve strays a
long way beyond the neck to
supply structures in the thorax
and abdomen as well; its name
means wandering or straying
First rib
First intercostal nerve
Anterior branch of T1
(first thoracic) spinal nerve
Phrenic nerve
Comes from the third, fourth,
and fifth cervical nerves; supplies
the muscle of the diaphragm and
the membranes lining either side
of it—the pleura on the thoracic
side and peritoneum on
the abdominal side
ANTERIOR (FRONT)
Sixth rib
THORAX Eighth rib
NERVOUS
Eighth
Pairs of spinal nerves emerge via the intervertebral foramina (openings) intercostal nerve
between the vertebrae. Each nerve splits into an anterior and a Like each intercostal
posterior branch. The posterior branch supplies the muscles and skin nerve, this supplies the
of the back. The anterior branches of the upper 11 thoracic spinal muscles lying in the
nerves run, one under each rib, as intercostal nerves, supplying the same intercostal space,
intercostal muscles and overlying skin. The anterior branch of the last
thoracic spinal nerve runs under the twelfth rib as the subcostal nerve. and also supplies
In addition to motor and sensory fibers, thoracic spinal nerves contain sensation to a strip of
sympathetic nerve fibers that are linked by tiny connecting branches skin around the thorax
to the sympathetic chain or trunk (see p.61). This allows sympathetic
nerves originating from one level of the spinal cord to travel up and Twelfth rib
down, and spread out to several body segments.
Eleventh rib
Subcostal nerve
Anterior branch of T12
nerve, in series with the
intercostal nerves;
named subcostal as it
lies under the last rib