SYNOVIAL JOINTS Tendon Joint Extensor expansion 049
sheath capsule The extensor tendon
Synovial cavity inserts on the middle SKELETAL SYSTEM
of proximal and distal phalanges
interphalangeal joint Femur
Distal phalanx
Bursa under head
Middle phalanx Hyaline cartilage FINGER of gastrocnemius
muscle
Superficial flexor tendon Synovial cavity of distal Deep flexor tendon Femoral condyle
Splits around the deep flexor tendon interphalangeal joint Inserts on the distal Articular cartilage
to insert on the middle phalanx; flexes phalanx; flexes the distal Fibrous capsule
the proximal interphalangeal joint interphalangeal joint
Articular cartilage
Simple hinge joints Tendon of quadriceps Hyaline cartilage
The interphalangeal joints between the bones of the fingers femoris muscle covers the articular
are examples of simple hinge joints. They operate in a single surfaces of the tibia,
plane, moving in flexion and extension only. Collateral Suprapatellar bursa femur, and patella
ligaments bind the sides of adjacent phalanges and prevent Bursas—extra pockets of Tibia
any side-to-side movement. Like all synovial joints, the synovial fluid—may lubricate
articular surfaces of the bones are lined with hyaline cartilage. the movement of tendons Complex joint
The knee joint is a complex synovial joint,
Colored X-ray of the knee around joints with articular discs or menisci inside the
This X-ray of the knee shows the detail of the bones extremely synovial cavity. It is also a compound joint,
well, but soft tissues are only seen as subtle shadows. Other Articular cartilage since it involves more than two bones (the
forms of medical imaging, such as MRI and ultrasound, can of patella femur, tibia, and patella). Movements at the
be used to visualize other components of the joint, such as knee reflect the complex anatomy; it is a
the tendons, ligaments, and cartilage. Patella hinge joint, moving mainly in flexion and
extension, but some sliding and axial rotation
Thumb X-ray Prepatellar bursa of the femur on the tibia also occurs.
This X-ray of the
thumb shows the Synovial cavity
metacarpophalangeal Filled with a thin
joint (bottom) and film of lubricating
the interphalangeal
joint. Both are simple synovial fluid
hinge joints.
Infrapatellar
fat pad
Fatty tissue within the
synovial membrane
Subcutaneous
infrapatellar bursa
Meniscus
The knee joint contains
two crescent-shaped
articular discs or
menisci, made of
fibrocartilage, which
facilitate the complex
movements of this joint
Subtendinus
infrapatellar bursa
Tibial plateau
KNEE
050
ANATOMY
Facial muscles
Muscles open and close
the mouth and eyes and
give us facial expression
Platysma
Part of the muscles of
facial expression; it
tenses the neck
Trapezius Pectoralis minor
Deltoid Intercostal muscle
Acting as a whole, this While the diaphragm is the
muscle moves the arm out to main muscle used in breathing,
the side, in a movement the intercostal muscles
between the ribs also play a
called abduction role, by helping lift the ribs
upward and outward
Pectoralis major
Flexor compartment
Serratus anterior of the arm
Brachialis muscle flexes
Flexor compartment (bends) the elbow
of the arm
Posterior rectus sheath
Contains biceps Formed by the broad tendons,
brachii, which flexes the or aponeuroses, of the
shoulder and the elbow anterolateral abdominal muscles,
the rectus sheath has an anterior
Rectus abdominis and a posterior layer
Flexes the chest toward
Transversus abdominis
the pelvis, as in an The innermost of three sheetlike
abdominal crunch anterolateral (front side)
abdominal muscles
External oblique
Outermost of three sheetlike Flexor carpi ulnaris
abdominal muscles that form the
Flexor compartment
side wall of the abdomen of the forearm
Includes muscles that flex
Brachioradialis the fingers and thumb
Flexor compartment Gluteus medius
of the forearm Moves the thigh
outward in abduction
Includes muscles that flex the
wrist and fingers
Iliopsoas
Bends the thigh forward and
upward in a movement
called flexion
051
MUSCULAR SYSTEM
Adductor compartment
of thigh
These muscles bring the
thighs together
Extensor compartment
of the thigh
Patella
Extensor compartment
of the leg
ANTERIOR (FRONT)
DEEP
Extensor compartment
of the thigh
Largely made up of the
four-headed quadriceps
femoris muscle, which
straightens the knee joint
Calf muscles
Extensor compartment
of the leg
Includes muscles that move
the foot upwards at the
ankle, a movement called
dorsiflexion, and muscles
that extend the toes
ANTERIOR (FRONT)
SUPERFICIAL
MUSCULAR Muscles attach to the skeleton by means of tendons, aponeuroses
SYSTEM (flat, sheetlike tendons), and bands of connective tissue called fascia.
Muscles are well supplied with blood vessels and appear reddish;
tendons have a sparse vascular supply and look white. The “action” of
a muscle refers to the movement it produces as it contracts. Muscle
action has been investigated both by observing living people and by
dissection of cadavers to pinpoint the precise attachments of muscles.
Electromyography (EMG)—using electrodes to detect the electrical
activity that accompanies muscle contraction—has proved invaluable
in revealing which muscles act to produce a specific movement.
Occipital belly of 052
occipitofrontalis
Stretches from the frontal ANATOMY
bone to the occipital bone
Rhomboid muscles at the back of the skull
These muscles are rhomboid, or
Trapezius
lozenge-shaped Each of these muscles is
Erector spinae triangular, but together they form
a four-sided shape: a trapezium
Serratus anterior
Deltoid
Serratus posterior inferior A triangular muscle, like
The word serratus means the shape of the Greek
letter delta
serrated or “like a saw” in Latin:
this muscle has a jagged edge Short scapular muscles
Intercostal muscles Latissimus dorsi
This means the broadest
Extensor compartment muscle of the back in Latin
of the arm
Extensor compartment
This is the triceps’ medial of the arm
head, which lies beneath its Contains one muscle, the triceps,
which means three-headed; here
other two heads we can see the two superficial
parts of the muscle, the long and
Erector spinae lateral heads
This muscle group, as its
name suggests, helps keep External oblique
The fibers of this muscle
the spine erect run diagonally, or obliquely
Transversus abdominis Extensor compartment
This muscle, in the side of the of the forearm
abdomen, has fibers that run in a Includes muscles that
horizontal (transverse) direction extend the wrist and fingers
Extensor compartment Gluteus maximus
of the forearm The word gluteus comes
from the Greek for rump or
Includes muscles that extend the buttock; maximus means the
thumb or move it out to the side greatest in Latin
Gluteus medius
Piriformis
In Latin, the name of this
muscle, which lies deep in the
buttock, means pear-shaped
053
MUSCULAR SYSTEM
Flexor compartment
of the thigh
These muscles bend or flex
the knee; also known as the
hamstrings
Flexor compartment
of the leg
The most superficial muscle here is
gastrocnemius; the name comes from
the Greek word for calf, translating
literally as the belly of the calf
POSTERIOR (BACK) SUPERFICIAL
Adductor
compartment of
the thigh
Flexor
compartment
of the thigh
Flexor compartment
of the leg
Includes muscles
that move the foot
downward at the ankle
(plantarflexion), and that
flex or curl the toes
Fibular (peroneal)
muscles
Two muscles that
evert the foot (move
it outward), named
after the fibula bone
in the lower leg
POSTERIOR (BACK) DEEP
MUSCULAR Most muscle names are derived from Latin or Greek. They can refer
SYSTEM to a muscle’s shape, size, attachments, number of heads, position
or depth in the body, or the action it produces when it contracts.
Names that end in -oid refer to the shape of the muscle. Deltoid, for
example, means triangle-shaped, and rhomboid means diamond-
shaped. Many muscles have two-part names. These names often refer
to both a characteristic of the muscle and the muscle’s position in the
body. Rectus abdominis, for example, means straight [muscle] of the
abdomen, and biceps brachii means two-headed [muscle] of the arm.
Some muscles have names that describe their action, such as flexor
digitorum, which simply means flexor of the fingers.
Colored MRI scan: Temporalis 054
coronal section One of the muscles
Unlike plain radiographs, MRI and CT that move the jaw ANATOMY
scans show soft tissue detail, including during chewing
muscles. In the limbs, the bones and
subcutaneous fat are here colored Deltoid
purple, with muscles in green. Short scapular muscles
Problems with these muscles
Facial muscles can lead to osteoarthritis at
These muscles the shoulder joint
Serratus anterior
may be affected Anchors the scapula against
in a stroke the chest wall and also
helps move it
Pectoralis minor Erector spinae
This muscle moves
the shoulder blade Flexor compartment
of the forearm
Intercostal Some of these muscles attach
muscle from the medial epicondyle of
the humerus; this attachment
Brachialis is inflamed in “golfer’s elbow”
Located in the
flexor compartment Gluteus maximus
of the arm
Transversus
abdominis
With the other two more
superficial anterolateral
abdominal muscles, this
bends the trunk to the
side (lateral flexion) or to
the front (flexion)
Quadriceps Flexor compartment
femoris of the thigh
Largest muscle in Hamstring injuries are common
in athletes: the long muscles
the extensor in this compartment stretch
compartment of across two joints—the hip
and the knee—and are at risk
the thigh of tearing if overstretched
SIDE MUSCULAR
SYSTEM
Flexor compartment of the leg
These muscles combine to form the Achilles The force produced by muscles of different shapes varies. Long, thin
tendon muscles tend to contract a lot but exert low forces. Muscles with
Achilles tendon, which can be many fibers attaching to a tendon at an angle, such as the deltoid,
ruptured if overstretched in a shorten less during contraction but produce greater forces. Although 055
the shape of muscles varies, there is a general rule that the force
sport injury generated by the contracting muscle fibers will be directed along the MUSCULAR SYSTEM
line of the tendon. Muscle fibers will enlarge in response to intense
Extensor compartment of the leg exercise. Conversely, if muscles are unused for just a few months, they
The bony attachments of these start to waste away. Consequently, physical activity is very important
in maintaining muscle bulk.
muscles can become inflamed and
painful in the condition “shin splints”
Colored MRI scan:
parasagittal section
This section through the body is to
the side of the midline, so we see a
slice through the leg. The muscles
of the back—mainly erector
spinae—are colored green, lying
behind the spine.
ANTERIOR (FRONT) Trapezius
Occipitalis
Pectoralis major Sternocleidomastoid
Splenius capitii
Subscapularis Ligamentum nuchae
Biceps Deltoid
brachii Infraspinatus
Temporalis
Orbicularis oculi
Levator labii superioris
Levator anguli oris
Zygomaticus major
Temporalis
Buccinator
Masseter
Depressor labii
inferioris
Depressor
anguli oris
Supraspinatus
Iliacus Subscapularis Deltoid Gluteus
Piriformis Pectoralis major Supraspinous ligament medius
Pectoralis minor
Deltoid Triceps brachii Gluteus
Coracobrachialis medial head minimus
Brachialis Common extensor origin Gluteus
Triceps brachii maximus
Brachioradialis
Supinator
Brachialis Flexor carpi ulnaris
Biceps brachii Flexor digitorum
profundus
Flexor digitorum
superficialis Abductor pollicus
Pronator teres longus
Flexor pollicis longus
Flexor digitorum Extensor pollicus
profundus longus
Pronator quadratus
Brachioradialis Brachioradialis
Iliopsoas Flexor pollicis First dorsal
Adductor magnus longus interosseus
Vastus intermedius
Adductor pollicis Fourth dorsal
Adductor magnus (transverse head) interosseus
Sartorius
Gracilis Flexor digitorum Dorsal
Quadriceps femoris superficialis expansion
(via patellar tendon)
Flexor digitorum profundus
Semitendinosus
Fibularis (peroneus) and shortens. These are relative terms and depend on the way the muscle is MUSCLE Adductor brevis
longus Vastus lateralis
Tibialis anterior ATTACHMENTS being is used at any given time. Conventionally, muscle attachments on the Adductor longus
Extensor digitorum
longus Gastrocnemius
Fibularis (peroneus) medial head
brevis
Gastrocnemius
lateral head
Popliteus
Soleus
a groove (sulcus) in the bone. or trochanter. Similarly, the muscle’s tendon may attach to a pit (fossa) or that, depending on its shape, might be called a process, tubercle, tuberosity, Attachment sites vary in appearance. They may occur at a prominent bump skeleton are shown with the origins in red and the insertions in blue. The attachments of muscles to bones are sometimes referred to as origins and Tibialis
insertions. The origin indicates the attachment that generally stays fixed, while posterior
the insertion refers to the attachment that moves when the muscle contracts
Flexor digitorum longus
ANTERIOR (FRONT) Fibularis (peroneus) Flexor hallucis longus POSTERIOR (BACK)
tertius
Fibularis (peroneus)
Extensor haliucis longus brevis
Extensor digitorum brevis Calcaneal tendon
Fibularis (peroneus) brevis
Dorsal interosseus
Extensor hallucis longus
and brevis
058 Perimysium
ANATOMY Fascicle
A bundle of muscle fibers,
Epimysium packed in connective tissue
called endomysium and
contained in a sheath
of perimysium
Parallel bundles Whole muscle Muscle fiber
Skeletal muscle includes familiar muscles Made up of fasciculi Formed by many cells merged
such as biceps or quadriceps. It is composed and covered in a layer together, and therefore
of parallel bundles of muscle fibers, which of fascia (fibrous tissue) containing many nuclei, these
are conglomerations of many cells. Skeletal cylindrical units range from
muscles are supplied by somatic motor called epimysium a few millimeters to several
nerves, which are part of the peripheral centimeters in length
nervous system (see p.296) and are Sarcoplasm
generally under conscious control. Cytoplasm (see Capillaries
p.21) of muscle These lie within the
Myofibril endomysium and
Fibers that contain filaments cell; contains supply the fibers
made of contractile proteins, many nuclei
mainly actin and myosin; the
way these filaments are
organized gives skeletal muscle
a striped or striated appearance
under a light microscope
Anisotropic or A band
Z disk
M line
Isotropic or I band
Z disk M line
In the center of the In the center of the
I band, this anchors A band, this connects
the thick filaments
the thin filaments
Thin filament Tropomyosin
Mainly composed Actin-bonding protein
of the protein actin
Thick filament Actin
Composed of the
protein myosin
Myosin head
SKELETAL MUSCLE
MUSCLE 059
STRUCTURE
MUSCULAR SYSTEM
Muscle cells possess a special ability to contract. Also called myocytes, muscle
cells are packed full of the long, filamentous proteins actin and myosin, which SMOOTH MUSCLE
ratchet past each other to change the length of the cell itself (see p.290).
There are three main types of muscle in the human body: skeletal or voluntary Smooth muscle cell
muscle, cardiac muscle, and smooth or involuntary muscle. Each of these These spindle-shaped cells
has a distinctive microscopic structure. Skeletal muscle also varies in its overall contain actin and myosin;
shape and structure, depending on its function. unlike in skeletal and cardiac
muscle, the proteins are not
CARDIAC MUSCLE lined up, so smooth muscle
does not appear striated
Intercalated disk
These elaborate junctions
firmly bind cardiac muscle
cells together
Cell nucleus Mitochondrion
Mitochondrion Cardiac Intermediate Actin filament
Muscle cells are muscle cell filament
packed with Myosin filament
Heart muscle Dense body
energy-producing Also called myocardium, cardiac Tapering cells
mitochondria muscle is only found in the Cell nucleus This type of muscle is made
heart. It exists as a network of Lies in the centre of individual, tapering cells and
Myofibril interconnected fibers, and it is supplied by autonomic
The myofibrils of cardiac spontaneously, rhythmically of the cell motor nerves, which control the
muscle are organized in a contracts. Autonomic nerves can operation of body systems, usually
increase or reduce the rate of at a subconscious level. It is
similar way to those in contraction, matching the heart’s found in the organs of the body,
skeletal muscle, giving a output to the body’s needs. particularly in the walls of tubes
striated appearance under such as the gut, blood vessels,
and the respiratory tract.
a light microscope
MUSCLE SHAPES
QUADRATE CIRCULAR OR
SPHINCTERIC
UNIPENNATE BIPENNATE MULTIPENNATE STRAP TRIANGULAR Muscular variation FUSIFORM
Skeletal muscles vary hugely in size and shape.
In some, such as strap or quadrate muscles, the
muscle fibers are parallel with the direction of
pull. In others, the fibers are obliquely oriented—
as in triangular or pennate (featherlike) muscles.
Brain 060
ANATOMY
Cranial nerves
Twelve pairs of cranial nerves
supply muscles and sensation
in the head and neck
Cervical spinal nerves Spinal cord
Emerge from the spinal cord
in the neck to supply the
neck and arm
Brachial plexus Musculocutaneous nerve
Anterior branches of the lower Supplies the muscles in the front
cervical spinal nerves, together of the upper arm, including the
biceps, as well as sensation to
with the first thoracic spinal the skin of the outer (lateral) side
nerve, form a network, or of the forearm
plexus, from which branches Axillary nerve
emerge to supply the arm, Supplies muscles and
forearm, and hand sensation around the
shoulder
Intercostal nerve
Anterior branches of the Radial nerve
thoracic spinal nerves travel Supplies muscles and
forward between the ribs as sensation on the back of
the arm, (including the
intercostal nerves; they triceps, forearm, and hand)
supply the muscles and skin
Cauda equina
of the thorax Below the end of the spinal
cord, the lumbar and sacral
Thoracic spinal nerves nerve roots continue for
some way inside the
Median nerve vertebral canal before
Supplies most of the emerging from the spine
muscles in the front of
the forearm, and also Ulnar nerve
Supplies two muscles in
some in the hand the forearm and many
of the small muscles in
Lumbar spinal nerves the hand
Lumbar plexus Sciatic nerve
Anterior branches of the Largest nerve in the body,
lumbar spinal nerves form a which supplies the
network here, from which hamstrings in the back of the
nerves emerge to supply the leg thigh; its branches supply
muscles and sensation in
Sacral spinal nerves the lower leg and foot
Femoral nerve Obturator nerve
Supplies sensation over Supplies the muscles and
the thigh and inner leg, skin of the inner thigh
and muscles in the front
of the thigh, including
the quadriceps
Sacral plexus
Anterior branches of sacral
spinal nerves come together
here as a network; the
network provides nerves to
the buttock and leg
Sympathetic trunks 061
Part of the autonomic
nervous system, the NERVOUS SYSTEM
sympathetic trunks extend
from the base of the skull
to the end of the vertebral
column, one on either side
Sympathetic ganglia
Collections of nerve cell
bodies form ganglia along
each trunk
Saphenous Ganglion impar
nerve The two sympathetic
Common peroneal trunks converge and end in
(fibular) nerve this single, unpaired
Branch of the sciatic ganglion, lying on the inner
nerve, supplying the surface of the coccyx
front and outer side
of the lower leg SYMPATHETIC TRUNK
Superficial
peroneal
(fibular)
nerve
Deep peroneal
(fibular) nerve
ANTERIOR (FRONT) Tibial nerve
Largest branch of the
sciatic nerve, supplying
the calf and foot
Dorsal digital branches
of fibular nerves
NERVOUS
SYSTEM
The nervous system contains billions of intercommunicating nerve neck; spinal nerves leave via gaps between vertebrae to supply the
cells, or neurons. It can be broadly divided into the central nervous rest of the body. You can also divide the nervous system by function.
system (brain and spinal cord) and the peripheral nervous system The part that deals more with the way we sense and interact with our
(cranial and spinal nerves and their branches). The brain and spinal surroundings is called the somatic nervous system. The part involved
cord are protected by the skull and vertebral column respectively. with sensing and controlling our internal environments—affecting
Cranial nerves exit through holes in the skull to supply the head and glands or heart rate, for example—is the autonomic nervous system.
PLACE HOLDER FOR Cerebrum 062
MRI IMAGES OF The largest part of the
NERVOUS SYSTEM brain, consisting of two ANATOMY
hemispheres; cerebrum
Head and neck Cranial nerves means brain in Latin
This colored MRI scan reveals the structures of Although the word cranium Cerebellum
the brain and upper spinal cord (orange–red). The Literally little brain in Latin,
brain stem emerges from the base of the brain to comes from the Greek for this part of the brain is
continue as the spinal cord. The branched skull, it is used more generally involved with balance and
cerebellum is visible at the lower back of the brain. coordination of movement
to mean head, so cranial Brain stem
means of the head Emerges from the foramen
magnum in the base of the skull
Spinal cord
The continuation of the Cervical spinal nerves
brain stem, lying protected Cervical means of the neck;
within the vertebral canal cervix is Latin for neck
of the spine Thoracic spinal nerves
Thorax is Latin for chest
Musculocutaneous nerve so the term thoracic
Like most peripheral nerves, this means of the chest
supplies both muscles and skin
Lumbar plexus
Axillary nerve The term lumbar relates to
Runs around the neck of the lower back and comes
the humerus. Axillary means from the Latin word
related to the armpit, from the lumbus, meaning loin
Latin word axilla, for armpit
Sacral plexus
Brachial plexus Sacral means of the
Brachial means of the arm, sacrum, the bony plate at
since brachium is the Latin the base of the vertebral
column—sacrum in Latin
word for arm means holy bone
Radial nerve Cauda equina
This nerve comes to lie The name of this bundle of
on the outer, or radial, nerve roots literally means
horse’s tail in Latin
side of the elbow
Intercostal nerve
Derives from the Latin
“inter” meaning between
and “costae” for ribs
Median nerve
The name comes from the
Latin for “in the middle”—
this nerve travels right
down the middle of the
arm and forearm
Ulnar nerve
This nerve lies on the
ulnar, or inner, side of
the arm and forearm
Femoral nerve
This means nerve of
the thigh—femur is
Latin for thigh
Obturator nerve Sciatic nerve
Passes out through the The name of this nerve is
derived from the French word
obturator foramen of “sciatique,” which itself comes
the pelvis to enter the from the Latin “ischiadicus,”
meaning of the hip
inner thigh
Spinal cord
The protective vertebrae surrounding the spinal
cord appear as blue blocks in this MRI of the spine.
The spinal cord is shown as a dark blue column
lying within the pale blue sheath of the dura mater.
Toward the lower right is the cauda equina.
SIDE NERVOUS
SYSTEM
Common fibular
(peroneal) nerve Twelve cranial nerves emerge from the brain and brain stem to supply
Lies on the outer side of structures in the head and neck, including the eyes, ears, nose, and
the leg and is named mouth. Thirty one pairs of spinal nerves sprout from the spinal cord,
after the bone around with eight cervical, twelve thoracic, five lumbar, five sacral, and one
which it wraps; perona is coccygeal on each side. These nerves branch to supply tissues behind
an alternative Latin and in front of the vertebral column. In the cervical, lumbar, and sacral
regions, nerves join together to form networks, or “plexuses,” before
name for fibula branching again to supply the limbs. Most peripheral nerves contain
both nerve fibers that carry messages out to muscles, and fibers that
Tibial nerve convey sensory information back to the central nervous system.
Named after the other
bone of the lower leg—the
tibia, or shinbone
Lower back 063
This color-enhanced X-ray of the lower back shows
the dural sac (white), which sheaths the spinal cord NERVOUS SYSTEM
and its emerging nerves. The column of vertebrae
(orange) ends in the sacrum, which connects the
vertebrae to the pelvis.
064 NEURON
ANATOMY Dendrite NERVE
From the Greek word STRUCTURE
Oligodendrocyte for tree, a dendrite
Manufactures the myelin receives incoming The nervous system is complex, containing billions of interconnecting
sheath along the axons in nerve impulses nerve cells, or neurons. Each neuron’s cell body has wiry projections
the central nervous system; (dendrites) sticking out of it. One is usually longer and thinner than
Schwann cells carry out this Nucleus the rest, and this is the axon. Some axons within the brain are less
function in the peripheral than 1/32 in (1 mm) in length; others, stretching from the spinal cord to
Cell body muscles in the limbs, can measure over 39 in (1 m) long.
nervous system
Node of Ranvier The movement of charged particles through channels in the
Gap between sections neuron’s membrane generates electrical impulses that travel along the
of the myelin sheath axon. Such impulses (known as action potentials) are conducted
slowly in axons without an insulating layer of myelin and tend to leak
Astrocyte away. In myelinated axons, a small patch of the membrane is exposed
Neuroglial cell between myelin segments and the impulse “jumps” to the next gap,
providing support which speeds up conduction. At the end of an axon, the signal is
and nourishment transmitted across a tiny gap (synapse), to the next neuron or to
to the neuron a muscle cell, by chemicals called neurotransmitters.
Parts of a neuron
This artwork shows the detailed structure
of a neuron from the central nervous system.
A single neuron such as this can make contact
with hundreds of other neurons, creating an
incredibly complex network of connections.
Axon
From the Greek for
axis or axle, this long
projection carries nerve
impulses away from
the cell body
Myelin sheath
Layers of myelin
insulate the axon; the
sheath is made of
fat-filled cells wrapped
around the axon
Synaptic knob Axon terminal
Transmits the impulse An end of the axon
via a synapse
Axon 065
Dendrite Cell body NERVOUS SYSTEM
Nerve fiber Myelin sheath
Endoneurium
Axon Nerve fascicle Layer of delicate
Bundle or group connective tissue
UNIPOLAR NEURON around the
of nerve fibers myelin sheath
Dendrite Cell body Perineurium Blood vessels
Sheathlike
wrapping
for a fascicle
BIPOLAR NEURON Axon Types of neuron Epineurium
Axon Neurons can be classified Strong, protective
Dendrite according to how many outer covering for
Cell body projections (dendrites and the whole nerve
axons) extend from the cell
MULTIPOLAR NEURON body. The most common PERIPHERAL NERVE Nerve structure
is multipolar, with three or Peripheral nerves comprise bundles
TYPES OF NEURON more projections. Unipolar of bundles of nerve fibers. Axons are
neurons lie mainly in the wrapped in a layer of packing tissue
sensory nerves of the called endoneurium. Small bundles
peripheral nervous system. of these nerve fibers are packaged in
Bipolar neurons are found perineurium to form fascicles, and
in only a few locations, several fascicles are bundled within
such as the eye’s retina. epineurium to form the nerve.
Structure of the spinal cord Nerve fiber tract White matter
Like the brain, the spinal cord contains grey Bundles of nerve fibers Made up of the axons of neurons
matter (mostly neuron cell bodies) and white carrying signals to and
matter (axons), and is covered in the same from the spinal cord Gray matter
three layers of meninges: dura mater, and the brain Cell bodies of neurons
arachnoid, and pia mater (see p.113).
Central canal
Spinal nerve Cerebrospinal fluid fills the narrow
Sensory and motor central canal and nourishes
nerve rootlets merge and protects neurons
to form a spinal nerve
Sensory nerve rootlet
Motor nerve rootlet Bundles of fibers emerging from
Bundles of fibers emerging the dorsal side (back) of the spinal
cord carry incoming signals from
from the ventral side sensors in the skin and muscles
(front) of the spinal cord
carry signals to skeletal and Sensory root ganglion
Cell bodies of sensory
smooth muscle nerves cluster in ganglia
Anterior fissure Pia mater Meninges
Deep groove along the Arachnoid Three layers of
front of the spinal cord Dura mater connective tissue that
protect the spinal cord
Subarachnoid
space
SPINAL CORD
066
ANATOMY
Nasal cavity Pharynx
Air is warmed, cleaned, and A passageway that connects
moistened as it passes over the richly the nasal cavities to the larynx,
vascular lining of the nasal cavity, as well as the oral cavity
before entering the pharynx to the esophagus
Nares (nostrils) Esophagus
Epiglottis Trachea
A fibromuscular tube, held
Larynx open by C-shaped rings of
The larynx, or voice box, is made of cartilage, which can be easily
cartilages, held together with fibrous felt in the front of the neck,
just above the sternum
membranes and muscles; it forms
part of the tract through which air passes Apex of
on its way to and from the lungs, as well left lung
as being the organ of the voice Rib
Intercostal muscle
Right lung
Possesses Left lung
Has two lobes, and
three lobes a concavity on its inner
surface to accommodate
the heart
Heart
Visceral pleura 067
This membrane covers
the surface of the lungs RESPIRATORY SYSTEM
themselves
Pleural cavity RESPIRATORY
Potential space between the SYSTEM
parietal and visceral layers
of the pleura, containing a Every cell in the human body needs to get hold of oxygen, and to get
thin film of pleural fluid that rid of carbon dioxide. These gases are transported around the body
lubricates the lungs as they in the blood, but the actual transfer of gases between the air and the
move within the chest blood occurs in the lungs. The lungs have extremely thin membranes
Parietal pleura that allow the gases to pass across easily. But air also needs to be
Membrane that lines the inner regularly drawn in and out of the lungs, to expel the building carbon
surface of the chest wall dioxide and to bring in fresh oxygen, and this is brought about by
Diaphragm respiration—commonly called breathing. The respiratory system
Main muscle of breathing, supplied includes the airways on the way to the lungs: the nasal cavities, parts
by the phrenic nerve; the diaphragm of the pharynx, the larynx, the trachea, and the bronchi (see p.151).
flattens as it contracts, increasing
the volume of the thorax, producing ANTERIOR (FRONT)
a drop in pressure inside the lungs
which draws breath into them
Internal carotid artery Internal jugular vein 068
Supplies blood to the brain Drains blood from the brain,
and from the face and neck ANATOMY
External carotid artery
Supplies the neck and tissues External jugular vein
of the head outside the skull Drains blood from the face
and scalp
Common carotid artery
Divides to form the external Subclavian artery
and internal carotid arteries Main artery supplying blood to
the arm, forearm, and hand
Brachiocephalic trunk
Divides to form the right common Subclavian vein
Main vein draining blood
carotid and subclavian arteries from the arm, forearm,
and hand
Brachiocephalic vein
Formed by the union of the Heart
internal jugular and Axillary artery
subclavian veins Continuation of the subclavian
artery, in the axilla or armpit
Arch of aorta
Cephalic vein
Superior vena cava Superficial vein, lying in the
Large vein formed by the joining subcutaneous tissue, draining the lateral
of the two brachiocephalic veins, side of the arm, forearm, and hand
returning blood from the head, Brachial artery
arms, and chest wall to the heart Continuation of the axillary
artery, in the upper arm
Descending aorta
The arch of the aorta becomes Brachial veins
the descending aorta, which runs A pair of veins that run with
down through the thorax and the brachial artery
into the abdomen Inferior mesenteric artery
Supplies the lower half of the
Hepatic veins large intestine and the rectum
Portal vein Common iliac arteries
A pair of arteries formed by
Superior mesenteric artery the division of the aorta
Branch of the abdominal aorta
Common iliac veins
supplying the small intestine A pair of veins that unite to
and part of the large intestine form the inferior vena cava
Renal artery Ulnar artery
Carries blood to Branches off the brachial
artery to supply the inner
the kidneys forearm and the hand
Renal vein Radial artery
Drains the kidney Branches off the brachial
artery to supply the outer
Superior mesenteric vein forearm and the hand
Inferior vena cava External iliac vein
Large vein draining blood Main vein carrying blood back
from the lower body and from the thigh, leg, and foot
returning it to the heart External iliac artery
Main artery supplying the
Internal iliac vein thigh, leg, and foot
Drains blood from the
pelvic organs
Internal iliac artery
Supplies the organs
within the pelvis
Basilic vein
Superficial vein draining the
medial side of the arm,
forearm, and hand
The heart and blood vessels deliver useful substances—oxygen from CARDIOVASCULAR ANTERIOR (FRONT) Femoral vein
the lungs, nutrients from the gut, white blood cells to protect against SYSTEM Continuation of the popliteal
infection, and hormones—to the tissues of the body. The blood also vein; this becomes the external
removes waste products and takes them to other organs—mainly the iliac vein at the groin
liver and kidneys—for excretion. The heart is a muscular pump that
Deep femoral artery
contracts to push blood through the body’s network of vessels. Branch of the femoral 069
Arteries are vessels that carry blood away from the heart; veins take artery supplying the
blood back to it. Arteries branch into smaller and smaller vessels, muscles of the thigh CARDIOVASCULAR SYSTEM
eventually leading to capillaries. Tiny vessels taking blood away from
capillary networks join up, like the tributaries of a river, to form veins. Femoral artery
Continuation of the external
iliac artery, in the thigh
Popliteal artery
Continuation of the
femoral artery, at
the back of the knee
Popliteal vein
Anterior tibial artery
Supplies muscles in front
of the tibia and fibula
Small saphenous vein
Shorter superficial vein
drains into the popliteal vein
at the back of the knee
Great saphenous vein
Long superficial vein of the
thigh and leg, ending in
the femoral vein
Posterior tibial artery
Supplies the calf and
sole of the foot
Peroneal artery
Supplies muscles in the
side of the lower leg
Posterior tibial vein
Runs with the posterior
tibial artery, draining deep
tissues in the calf
Anterior tibial vein
Runs with the anterior
tibial artery, draining deep
tissues in the shin
Artery of the
dorsum of the foot
Continuation of the
anterior tibial artery
External carotid artery Internal jugular vein 070
External jugular vein Internal carotid artery ANATOMY
From the Latin word
Arteries of the head and neck jugulum, which Subclavian vein
The aorta (bottom center on this colored CT scan) means neck
supplies blood to the head via the carotid arteries. Subclavian artery
Branching sideways at collarbone level are the Brachiocephalic trunk The name of this artery comes from
subclavian arteries, which transport blood to the The name of this large the Latin for “under the clavicle”
upper limbs. The pulmonary arteries are visible as a Superior vena cava
dense network of vessels on either side of the aorta. artery combines the Greek Vena cava means hollow vein
words for arm and head in Latin (although, of course,
all veins are hollow)
Brachiocephalic vein
Axillary artery
Arch of aorta Axilla means armpit in Latin
This great artery was first
given the name “aorta” by Azygos vein
Aristotle; rather strangely, it
comes from the Greek word Cephalic vein
A superficial vein of the upper limb
for hanger or strap
Brachial artery
Heart Brachium means arm in Latin
Inferior vena cava
Brachial vein
Descending aorta One of two veins that run
with the brachial artery in
Hepatic vein the upper limb
Celiac trunk Portal vein
The name of this artery Carries blood to the porta hepatis,
comes from the Greek or “gateway to the liver”
Radial artery
for belly or bowels Takes its name from the outer or
lateral forearm bone—the radius
Superior Ulnar artery
mesenteric vein Named after the inner or medial
forearm bone—the ulna
Superior mesenteric
artery Internal iliac artery
Branches of this run in Common iliac vein
the mesentery—the
Internal iliac vein
membrane surrounding
the intestines
Inferior
mesenteric artery
Gonadal vein
The word gonad comes
from the Greek for
generation or reproduction
Common iliac artery
Ilium is Latin for flank
Gonadal artery
External iliac artery
Femoral vein SIDE Deep femoral CARDIOVASCULAR
artery SYSTEM
Popliteal artery Femoral artery
The name comes from the Takes its name from
the femur, which
Latin for knee joint or means thigh in Latin
back of the knee
Small (lesser)
Popliteal vein saphenous vein
Anterior tibial vein The circulation can be divided in two: the pulmonary circulation 071
carries blood pumped by the right side of the heart to the lungs,
Anterior tibial artery and the systemic circulation carries blood pumped by the more CARDIOVASCULAR SYSTEM
powerful left side of the heart to the rest of the body. The pressure
Posterior tibial artery in the pulmonary circulation is relatively low, to prevent fluid being
This takes its name from forced out of capillaries into the alveoli of the lungs. The pressure
in the systemic circulation (which is what is measured with a blood-
the tibia, which means pressure cuff on the arm) is much higher, easily enough to push
shinbone in Latin blood all the way up to your brain, into all your other organs, and
out to your fingers and toes.
Peroneal (fibular) artery
Perona is a later Latin word
for fibula, and comes from
the Greek for pin
Posterior tibial vein
Artery of the
dorsum of the foot
Arteries of the abdomen and legs
This color-enhanced CT angiogram shows the
abdominal aorta and the arteries of the legs. Also
visible are the kidneys and spleen. The large artery
traveling through each thigh is the femoral artery;
this becomes the popliteal artery behind the knee
and branches into the tibial arteries in the lower leg.
072
ANATOMY
Tunica adventitia Tunica media Internal elastic lamina
The outermost coat, Consists mainly of smooth Prominent in large arteries, including
composed of connective muscle; this is the thickest
tissue and elastic fibers layer in an artery the aorta and its main branches;
the layer between the tunica
media and tunica intima
Tunica adventitia ARTERY Internal elastic lamina Tunica intima
Absent from some
Tunica media veins, including those
This layer of muscle around the brain
cells is thinner in veins
than in arteries
VEIN
Color doppler Endothelium
A doppler ultrasound probe A single layer of flattened
can detect the difference
between blood flowing to cells that forms the thin
and from the detector. This wall of capillaries
scan shows the blood that
flows in an artery in the leg
as red, and the blood in
the vein as blue.
CAPILLARY
ARTERY, VEIN, The cardiovascular system consists of the heart, tunica media, and the outer wrapping, or tunica
CAPILLARY blood, and blood vessels—comprising arteries, adventitia. While the tunica media is a thick layer
STRUCTURE arterioles, capillaries, venules, and veins. in arteries, it is very thin in veins, and completely
absent from capillaries, the walls of which comprise
The heart contracts to keep the blood just a single layer of endothelial cells.
continually moving through a vast network of
blood vessels. Arteries carry blood away from the The cardiovascular system carries oxygen from
heart to organs and tissues, whereas veins carry the lungs, nutrients from the gut, hormones, and
blood back to the heart. Both arteries and veins white blood cells for the body’s defense system. It
have walls made up of three main layers: the also picks up waste from all body tissues and carries
innermost lining or tunica intima, the middle it to the appropriate organs for excretion.
073
CARDIOVASCULAR SYSTEM
Tunica intima Artery cross section
The innermost lining of an artery;
made up of a single layer of flattened Arteries range from less
cells, also known as the endothelium than 1⁄25 in (1 mm) to up to
11⁄4 in (3 cm) in diameter
Valve
Allows blood to flow only Artery
toward the heart The largest arteries of the body contain
a good proportion of elastic tissue
within the internal elastic lamina and
tunica media layers. The thick walls and
elastic nature of arteries mean they can
withstand the high pressure that occurs
when the heart contracts and also keep
blood flowing between heartbeats.
There is less elastic tissue in smaller,
muscular arteries, and even less in the
smallest arteries, or arterioles.
Vein cross section
The largest veins
measure up to 11⁄4 in
(3 cm) in diameter
Capillary cross section Vein
Veins have much thinner walls than
Capillaries measure just arteries and contain proportionately less
⁄12,500 in (0.01 mm) in muscle and more connective and elastic
diameter—this capillary tissue. Capillaries converge to form tiny
is not shown to scale veins, or venules, which then join up to
with the other vessels form larger veins. Most veins contain
simple, pocketlike valves to keep
blood flowing in the right direction.
Capillary
The walls of a capillary are extremely
thin, formed by just a single layer of
flattened cells. This allows substances
to transfer between the blood inside
the capillary and the surrounding tissue.
Some capillaries have pores, or
fenestrations, to make the exchange
of substances even easier.
Single cell Cell nucleus Kidney capillary cast
Capillaries are so small To reveal the dense
network of capillaries
that just one or two inside the kidney, resin has
cells wrap around been injected into the
their diameter renal artery and allowed to
set. The tissue of the organ
has dissolved away.
074
ANATOMY
Preauricular nodes Superficial cervical nodes
Subparotid nodes
Pretracheal nodes
Prelaryngeal nodes
Deep cervical nodes Left subclavian vein
Lymph from the
Jugular veins thoracic duct enters
Right subclavian vein bloodstream here
Lymph from right arm, and
right side of head and chest Spleen
enters bloodstream here Contains lymphocytes
and filters blood; the
Superior vena cava largest organ in the
lymphatic system
Axillary nodes
Pre- and para-aortic nodes
Parasternal nodes Pre-aortic nodes lie on the aorta
in the abdomen and drain lymph from
Thoracic duct the gut and digestive organs into the
lumbar lymph trunk on each side.
Cisterna chyli Para-aortic nodes lie on each side of
the aorta and drain lymph from the
Supratrochlear nodes legs and posterior wall of the abdomen
Lymph from the hand
and forearm drains to Internal iliac nodes
nodes at the elbow
Lateral aortic nodes
External iliac nodes
Inguinal nodes
Lymphatics 075
Valved vessels transport
lymph fluid around the body LYMPHATIC AND IMMUNE SYSTEM
in a similar way to veins
transporting blood ANTERIOR (FRONT)
Popliteal nodes LYMPHATIC
A group of around AND IMMUNE
six nodes sit within SYSTEM
the popliteal fossa,
at the back of the The lymphatic system is closely related to the cardiovascular system.
It consists of a network of lymphatic vessels that collect tissue fluid
knee joint from the spaces between cells. Instead of carrying this fluid straight
back to veins, the lymphatic vessels deliver it to lymph nodes first.
These nodes, like the tonsils, spleen, and thymus, are “lymphoid
tissues,” meaning that they all contain immune cells known as
lymphocytes. The nodes are therefore part of the immune system.
There are also patches of lymphoid tissue in the walls of the bronchi
and the gut. The spleen, which lies tucked up under the ribs on the
left side of the abdomen, has two important roles: it is a lymphoid
organ, and it also removes old red blood cells from the circulation.
076
ANATOMY
Lymph node Jugulodigastric Occipital nodes
There are around 450 lymph nodes in the adult body. node
Lymph nodes vary in size from 1/32 in (1 mm) to over 1 in (2 cm) Cervical nodes
in length and tend to be oval. Several lymphatic vessels bring Submental A chain of lymph nodes that receive
lymph to the node, and a single vessel carries it away. nodes the lymph from the head and neck. The
superficial cervical nodes lie along the
Pretracheal external jugular vein; the deep cervical
nodes nodes lie along the internal jugular vein
Parasternal Thoracic duct
nodes
Axillary nodes
Cross section of a lymph node Drain upper trunk and arm
Lymph nodes possess a capsule (stained pink in this section), Intercostal nodes
an outer cortex packed full of lymphocytes (deep purple),
and an inner medulla made up of lymphatic channels (blue). Spleen
Pre-aortic Supratrochlear nodes
nodes Drain the inner side of the
arm and forearm
Inguinal nodes
Drain the lower Common iliac nodes
Internal iliac nodes
trunk and leg
External iliac nodes
077
LYMPHATIC AND IMMUNE SYSTEM
LYMPHATIC The immune system is the body’s defense mechanism against external
AND IMMUNE and internal threats. Skin forms a physical barrier to infection, and the
SYSTEM antibacterial sebum secreted onto it is a chemical barrier. There are
also important immune molecules, including antibodies, and a great
range of immune cells, including lymphocytes, that are all made in
the bone marrow. Some lymphocytes mature in the bone marrow,
whereas others move to the thymus to develop. The thymus is a large
gland, low in the neck in children (see p.161), which largely disappears
in adulthood. Mature lymphocytes take up residence in the lymph
nodes, where they check incoming tissue fluid for potential invaders.
SIDE
Lymphatics
Popliteal nodes
Lymphoid tissue Blood vessels of lymph node
At a high magnification, individual lymphocytes (purple) can This image, produced using a scanning electron microscope,
be seen in a section of lymphoid tissue. The blue circle in the shows a resin cast of the dense network of tiny blood vessels
image is an arteriole, packed full of blood cells (stained pink). inside a lymph node.
Parotid gland 078
The largest of the
ANATOMY
salivary glands
DIGESTIVE SYSTEM
Mouth
The mouth is primarily The digestive system comprises the organs that enable us to take in
designed for taking in food, food, break it down physically and chemically, extract useful nutrients
from it, and excrete what we don’t need. This process begins in the
but it is also used for mouth, where the teeth, tongue, and saliva work together to form a
speaking and breathing food into a moist ball that can be swallowed. The mouth, pharynx,
stomach, intestines, rectum, and anal canal form a long tube that is
Parotid (Stensen’s) duct referred to as the digestive tract. It usually takes between one and
Opens into the cheek two days for ingested food to travel all the way from the mouth to the
anus. Other organs—including the salivary glands, liver, gallbladder,
lining, next to the upper and pancreas—complete the digestive system.
second molar teeth Larynx
Tongue Pharynx
A mass of muscles, the Connects the mouth
tongue moves food around to the esophagus
in the mouth, and also
carries the taste buds
Teeth
A range of different teeth bite,
slice, and grind up the food
that comes into the mouth
Sublingual gland
Submandibular duct
Submandibular salivary gland
One of three pairs of large salivary
glands which empty their secretions
into the mouth through their ducts
Epiglottis
Flap of cartilage at the base
of the tongue that folds
backward during swallowing
to cover the larynx
Esophagus
Contractions in the muscular
wall of the esophagus carry
food down to the stomach
Liver Stomach
The largest organ in the human An expandable bag, the stomach
holds food and releases it bit by
body, the liver produces bile bit into the small intestine. It also
and receives all the nutrients secretes hydrochloric acid, which
kills dangerous ingested bacteria
absorbed from the gut
Large intestine
Gallbladder This comprises the cecum and
This baglike organ stores the colon. The large intestine
bile until it is needed in the is where water is absorbed from
digested food
small intestine
Small intestine
Pancreas Comprising the duodenum,
Partially hidden behind jejunum, and ileum, the small
the stomach, the pancreas intestine is where food is digested
produces hormones (including and nutrients are absorbed
insulin), and makes enzymes that
aid digestion, which it secretes Rectum
into the small intestine This is a holding station for the
waste products of digestion,
Appendix which are known as feces
Dead-end tube attached to
the last part of the large
intestine, with no function in
modern humans
Anal canal
The last few inches of the
digestive tract carry feces
(waste food) from the
rectum to the anus, from
where they are expelled
from the body
079
DIGESTIVE SYSTEM
080 Left
suprarenal
ANATOMY gland
Left kidney
URINARY Lies behind
SYSTEM the stomach
and spleen
The urinary system comprises the kidneys, Left renal artery
ureters, bladder, and urethra. The kidneys lie A branch from the
high up in the abdomen, on its back wall. abdominal aorta
The upper part of both kidneys is tucked Left renal vein
under the twelfth rib. The kidneys filter the
blood and ensure that it stays at exactly Left ureter Abdominal
the right volume and concentration to keep aorta
all the cells in the body working properly.
They also get rid of unwanted substances Right ureter
from the blood, playing an important role in Inferior vena cava
excreting nitrogen-containing urea, for Large vein that lies right at the
example. The urine made by the kidneys is back of the abdomen, carrying
carried by the ureters down to the bladder, deoxygenated blood from the
which lies in the pelvis. The urethra runs from legs and trunk back to the heart
the bottom of the bladder and opens to the
outside world. In a woman, the urethra is Right
short—only a few inches long—and opens at suprarenal
the perineum, between the legs. The urethra
of a man is longer, running through the gland
length of the penis to open at the tip. Right kidney
Sits a little lower
than the left
kidney, under
the liver
Right renal
artery
Right renal vein
Drains into the
inferior vena cava
Common iliac Common ANTERIOR (FRONT) / MALE
artery iliac vein
Ureters Bladder
A muscular bag
Bladder that can hold
up to 1 pint
Urethra (0.5 liters) of urine
The female urethra is
around 11/2 in (4 cm) Prostate gland
long. It passes through Surrounds the
the muscle of the commencement
pelvic floor and a of the male urethra
muscular sphincter
before opening Urethra
between the clitoris The male urethra
and vagina is about 8 in
(20 cm) long
ANTERIOR (FRONT) / FEMALE 081
URINARY SYSTEM
082 Lactiferous duct
A series of 15 to 20
ANATOMY
ducts each drain
REPRODUCTIVE a lobe of the breast
SYSTEM
Nipple
FEMALE Lactiferous ducts open on
Most organs in the body are similar in men highest point (apex) of
and women. However, when it comes to the nipple, which extends
the reproductive organs, there is a world of from center of the breast
difference. In a woman, the ovaries, which
produce eggs and female sex hormones, Secretory lobule
are tucked away, deep inside the pelvis. containing alveoli
Also located within the pelvis are the One of several small
vagina, uterus, and paired oviducts, or compartments housed
fallopian tubes, in which eggs are conveyed within each lobe of the
from the ovaries to the uterus. The woman’s
reproductive system also includes the breast. A lobule is
mammary glands, which are important composed of grapelike
in providing milk for the newborn. clusters of milk-secreting
MALE glands called alveoli
In a man, the testes, which produce sperm
and sex hormones, hang well outside the
pelvis, in the scrotum. The rest of the male
reproductive system consists of a pair
of tubes called the vasa deferentia
(singular, vas deferens), the accessory
sex glands (the seminal vesicles and
the prostate), and the urethra.
ANTERIOR (FRONT) / FEMALE
Oviduct
Also known as
fallopian tubes,
oviducts collect
eggs produced at
ovulation and
transport them to
the uterus; oviducts
are also the place
where fertilization
normally occurs
Fimbriae Ovary
Fingerlike Female gonad; is
projections that hidden away, deep
form a feathery end within the pelvis
to each oviduct
Fundus of uterus
Vas deferens The uterus is angled forward,
so the fundus—the farthest
Seminal vesicle point from the opening—lies
Contributes fluid to semen toward the front
Prostate gland Body of uterus 083
Accessory gland located at the
base of the bladder; contributes Cervix of uterus REPRODUCTIVE SYSTEM
some fluid to semen The cervix, or neck of the
uterus, projects down into
Shaft of penis the vagina
Formed by masses of erectile
tissue, which become engorged Vagina
with blood during erection Flexible muscular tube that
accommodates the male
Urethra penis during coitus; during
Conveys sperm and childbirth, it expands to allow
urine through penis the fetus to pass through
ANTERIOR (FRONT) / MALE Epididymis
A much-coiled tube on the
back of the testis; sperm are
stored and mature here
Glans penis
Testis
Male gonad; hangs outside
body cavity, in the scrotum
Scrotum
Pouch of skin and muscle
that encases testis
084
ANATOMY
Pineal gland
Tiny gland that produces
a number of hormones,
including melatonin
Hypothalamus
Part of the brain, lying under
the thalamus—the stalk of the
pituitary gland is attached to
the hypothalamus
Pituitary gland
Only 3/8 in (1 cm) in diameter;
hangs under the hypothalamus,
in a saddle-shaped fossa
(depression) in skull
Parathyroid gland
Four pea-sized glands at the
back of the thyroid; these
help regulate calcium levels
in the body
Thyroid gland
Lies in the neck, in front of the
trachea, and produces hormones
that stimulate metabolism
ENDOCRINE SYSTEM ANTERIOR
(FRONT)
The body’s internal environment is controlled and regulated by nerves
and hormones. The autonomic nervous system uses nerve impulses
and neurotransmitters to send information in a swift and localized way.
The glands of the endocrine system produce hormones—chemical
messengers, often carried in the blood—that act in a slower, more
prolonged, and more generalized way. Both the autonomic nervous
system and the endocrine system are governed by the hypothalamus
in the brain. The pituitary gland produces hormones that affect other
endocrine glands, which sometimes form discrete organs. There are
also hormone-producing cells in the tissues of many other organs.
Adrenal gland Pancreas
A pair of glands, also known Has cells that produce hormones
controlling glucose metabolism:
as suprarenal glands, that insulin and glucagon; also
produce epinephrine, also produces digestive enzymes
called adrenaline
Ovary
Ovaries produce sex
hormones as well as
gametes (reproductive
cells) called ova
FEMALE Testis 085
Testes produce sex
hormones as well as ENDOCRINE SYSTEM
gametes (reproductive
cells) called sperm
THORAX ABDOMEN
AND PELVIS
Skeletal pp.136–41
Muscular pp.142–47 Skeletal pp.168–73
Nervous pp.148–49 Muscular pp.174–77
Respiratory pp.150–53 Nervous pp.178–79
Cardiovascular pp.154–59 Cardiovascular pp.180–81
Lymphatic and Lymphatic and
immune pp.160–61 immune pp.182–83
Digestive pp.162–63 Digestive pp.184–89
Reproductive pp.164–65 Urinary pp.190–91
MRI scans pp.166–67 Reproductive pp.192–95
MRI scans pp.196–97
HEAD
AND NECK
Skeletal pp.88–97 SHOULDER AND LOWER ARM
Muscular pp.98–103 UPPER ARM AND HAND
Nervous pp.104–121
Respiratory pp.122–23 Skeletal pp.198–203 Skeletal pp.222–25
Cardiovascular pp.124–27 Muscular pp.204–11 Muscular pp.226–29
Lymphatic and Nervous pp.212–15 Nervous pp.230–31
immune pp.128–29 Cardiovascular pp.216–19 Cardiovascular pp.232–33
Digestive pp.130–31 Lymphatic and MRI scans pp.234–35
Endocrine pp.132–33 immune pp.220–21
MRI scans pp.134–35
HIP LOWER LEG ANATOMY
AND THIGH AND FOOT ATLAS
Skeletal pp.236–41 Skeletal pp.260–63
Muscular pp.242–49 Muscular pp.264–67
Nervous pp.250–53 Nervous pp.268–69
Cardiovascular pp.254–57 Cardiovascular pp.270–71
Lymphatic and MRI scans pp.272–73
immune pp.258–59
The Anatomy Atlas splits the body into seven regions,
starting with the head and neck and working down to the
lower leg and foot. Each region is explored through the
systems within it: skeletal, muscular, nervous, respiratory,
cardiovascular, lymphatic and immune, endocrine, and
reproductive. MRI scans at the end of each section show
a series of real-life images through the body.
088Parietal bonesOccipitalFrontal bone
Paired bones forming most bone
ANATOMYof the roof and sides of skullCoronal suture
Where the frontal and
HEAD AND NECKSagittal sutureparietal bones meet;
SKELETAL crosses the skull’s highest
Lambdoid suture part (the crown)
The skull comprises the cranium and mandible.Joint between occipital and
It houses and protects the brain and the eyes, ears,parietal bonesBregma
nose, and mouth. It encloses the first parts of theWhere the sagittal and
airway and of the alimentary canal, and providesLambdacoronal sutures meet
attachment for the muscles of the head and neck.Point where the sagittal suture
The cranium itself comprises more than 20 bonesmeets the lambdoid sutureSagittal suture
that meet each other at fibrous joints called sutures.Joint on the midline
In addition to the main bones labeled on theseOccipital bone(sagittal plane) where
pages, there are sometimes extra bones along theForms lower part of backparietal bones meet
sutures. In a young adult skull, the sutures areof skull, and back of
visible as tortuous lines between the cranial bones;cranial baseParietal bone
they gradually fuse with age. The mandible of aFrom the Latin for wall
newborn baby is in two halves, with a fibrous joint
in the middle. The joint fuses during early infancy,
so that the mandible becomes a single bone.
TOP
BACK
Frontal bone
Superciliary arch
Glabella Also called the supraorbital
Area between the two ridge, or brow ridge; from
the Latin for eyebrow
superciliary arches;
glabella comes from the Nasal bone
Two small bones form the
Latin for smooth, and bony bridge of the nose
refers to the bare area
between the eyebrows Orbit
Technical term for
Supraorbital foramen the eye-socket, from the
The supraorbital nerve Latin for wheel-track
passes through this hole Frontal process
to supply sensation to of maxilla
the forehead Rises up on the medial
(inner) side of the orbit
Zygomatic process
of frontal bone Piriform aperture
Pear-shaped (piriform)
Runs down to join the opening; also called the
frontal process of the anterior nasal aperture
zygomatic bone Inferior nasal concha
Lowest of the three curled
Superior orbital fissure protrusions on the lateral
Gap between the sphenoid wall of the nasal cavity
bone’s greater and lesser Zygomatic process
wings, opening into the orbit of maxilla
Part of the maxilla that
Inferior orbital fissure projects laterally (to the side)
Gap between the maxilla
and the greater wing of the
sphenoid bone, opening
into the back of the orbit
Infraorbital foramen
Hole for infraorbital branch
of maxillary nerve to supply
sensation to the cheek
Nasal crest
Where the two maxillae
meet; the vomer (part of
the septum) sits on the crest
ANTERIOR (FRONT) Ramus of mandible Alveolar process of maxilla
Part of the mandible, Part of the maxilla that holds
named after the Latin the upper teeth; alveolus
(meaning small cavity) refers
for branch to a tooth socket
Maxilla Mandible
Latin word for jaw; the The jawbone; its name
maxilla bears the upper comes from the Latin verb
teeth and also encloses meaning to chew
the nasal cavity Mental foramen
Hole that transmits
Cervical vertebra branches of the mandibular
There are seven vertebrae in nerve; mental can refer to
the neck region of the spine the chin (mentum in Latin)
First rib Mental protuberance
Several small muscles in The chin’s projecting lower
edge—more pronounced in
the neck attach to the men than in women
small, C-shaped first rib
Clavicle
Bone that supports the shoulder and
gives attachment to the trapezius
and sternocleidomastoid muscles
Tympanic part of Coronal suture 090
temporal bone
Forms floor of the Zygomatic arch ANATOMY
Formed by the zygomatic
external acoustic meatus, HEAD
at the inner end of which process of the temporal AND NECK
bone projecting forwards to SKELETAL
lies the tympanic meet the temporal process
membrane, or eardrum The cervical spine includes seven vertebrae, the top
of the zygomatic bone two of which have specific names. The first
Parietal bone vertebra, which supports the skull, is called the
Condyle atlas, after the Greek god who carried the sky on his
Squamosal suture Condylar process shoulders. Nodding movements of the head occur
The articulation between projects upwards to at the joint between the atlas and the skull. The
squamous part of temporal end as the condyle, or second cervical vertebra is the axis, from the Greek
bone and parietal bone head of the mandible, word for axle, so-called because when you shake
which articulates with your head from side to side, the atlas rotates on the
Parietomastoid suture the cranium at the axis. In this side view, we can also see more of the
Here the parietal bone meets temporomandibular bones that make up the cranium, as well as the
the posterior, mastoid part of temporomandibular ( jaw) joint between the
( jaw) joint mandible and the skull. The hyoid bone is also
the temporal bone visible. This small bone is a very important anchor
for the muscles that form the tongue and the
Occipitomastoid suture floor of the mouth, as well as muscles that
Fibrous joint between the attach to the larynx and pharynx.
Frontal bone
occipital bone and the
mastoid part of the Pterion
temporal bone Area on side of skull
where the frontal, parietal,
Lambdoid suture temporal, and sphenoid
bones come close together;
Occipital it is a key surgical landmark
bone because the middle
meningeal artery runs up
Asterion inside the skull at this point
From the Greek for and may be damaged by a
star; it is where the fracture to this area
lambdoid, Greater wing of
occipitomastoid, sphenoid bone
and parietomastoid
Coronoid process
sutures meet of mandible
Takes its name from the
Temporal bone Greek word for crow
because it is curved like
a crow’s beak; this is where
the temporalis muscle
attaches to the jawbone
Lacrimal bone
Takes its name from the
Latin for tear; tears drain
from the surface of the
eye into the nasolacrimal
duct, which lies in a groove
in this bone
Nasal bone
Zygomatic bone
From the Greek for yoke;
it forms a link between
the bones of the face
and the side of the skull
Styloid process Maxilla
Named after the Greek for
pillar, this pointed projection Alveolar process
sticks out under the skull and of mandible
forms an anchor for several The part of the
slender muscles and ligaments jawbone bearing
the lower teeth
Mastoid process
The name of this Mental foramen
conical projection under Body of mandible
the skull comes from the
Ramus of mandible
Greek for breast
Hyoid bone
Angle of mandible Takes its name from the Greek
Where the body of the for U-shaped; it is a separate
mandible turns a corner bone, lying just under the
mandible, that provides an
to become the ramus anchor for muscles forming
the floor of the mouth and the
tongue; the larynx hangs below it
091
HEAD AND NECK • SKELETAL
SIDE
092 Occipital bone
ANATOMY External occipital protuberance
Superior nuchal line Foramen magnum
The trapezius and sternocleidomastoid
Lambdoid
muscles attach to this ridge suture
Inferior nuchal line Pharyngeal
Slight ridge lying between the tubercle
attachments of some of the Jugular foramen
deeper neck muscles
Carotid canal
Hypoglossal canal The internal
carotid artery
Occipital condyle enters here
Where the skull
Stylomastoid
articulates with the foramen
atlas (first cervical The facial nerve
vertebra) emerges through
this hole
Foramen lacerum
Fibrocartilage-filled Styloid process
hole between the Foramen
body of the spinosum
phenoid bone and Foramen ovale
the petrous part of The mandibular
the temporal bone division of the
trigeminal nerve goes
Digastric notch through this hole
The posterior belly
Lateral
of the digastric pterygoid plate
muscle attaches An anchor point
for jaw muscles
to this pit
Pterygoid
Mastoid process hamulus
The word hamulus
Tympanic part of means small hook
temporal bone in Latin
Zygomatic arch
Mandibular fossa
Socket for the Interpalatine suture Lesser palatine
Joint between the
temporomandibular horizontal plates of the foramina
( jaw) joint two palatine bones The lesser palatine
arteries and nerves
Articular enter here to
eminence supply the soft
The condyle of the palate
mandible moves
forward onto this Greater palatine
area as the
jaw opens foramen
Entry point for the
Medial pterygoid greater palatine
plate artery and nerve,
which supply the
Forms the back of hard palate
the side wall of the
Incisive fossa
nasal cavity The nasopalatine nerve emerges here to
supply sensation to the front of the palate
Choana
Opening of the nasal
cavity into the pharynx;
from funnel in Greek
Zygomatic process of maxilla
Vomer
Posterior nasal spine
Palatomaxillary suture
Palate
Intermaxillary suture
UNDERSIDE OF SKULL
093
HEAD AND NECK • SKELETAL
HEAD AND NECK The most striking features of the skull viewed from these angles are
SKELETAL the holes in it. In the middle, there is one large hole—the foramen
magnum—through which the brain stem emerges to become the
spinal cord. But there are also many smaller holes, most of them
paired. Through these holes, the cranial nerves from the brain escape
to supply the muscles, skin, and mucosa, and the glands of the head
and neck. Blood vessels also pass through some holes, on their way
to and from the brain. At the front, we can also see the upper teeth
sitting in their sockets in the maxillae, and the bony, hard palate.
Foramen magnum Internal occipital
Latin for large hole; the brain protuberance
Located near the
stem emerges here confluence of the sinuses,
where the superior sagittal,
Hypoglossal canal transverse, and straight
The hypoglossal nerve, sinuses (the large veins in
the dura mater) meet
supplying the tongue
muscles, exits here Mastoid foramen
An emissary (valveless)
Internal acoustic meatus vein passes out
The facial and through this hole
vestibulocochlear nerves Jugular foramen
pass through this hole The internal jugular vein
and the glossopharyngeal,
Basiocciput vagus, and accessory nerves
Part of the occipital bone, in emerge from this hole
front of the foramen magnum,
that fuses with the body of the Petrous part of
temporal bone
sphenoid bone
Foramen lacerum
Foramen spinosum
Entry point of the middle Foramen ovale
meningeal artery, which Pituitary fossa
supplies the dura mater
and the bones of the skull Foramen rotundum
The maxillary division of
Lesser wing of sphenoid bone the trigeminal nerve passes
through this round hole
Optic canal
Orbital part of
Cribriform plate of ethmoid frontal bone
Area of the ethmoid bone Part of the frontal bone
pierced by holes, through that forms the roof of
which the olfactory nerves the orbit, and also the
pass. Cribriform is Latin for floor at the front of
the cranial cavity
sievelike; ethmoid, taken from
Greek, also means sievelike Crista galli
Vertical crest on the
Foramen cecum ethmoid bone that takes
Named after the Latin word for its name from the Latin for
cock’s comb; it provides
blind, this is a blind-ended pit attachment for the falx
cerebri—the membrane
INTERNAL SURFACE OF BASE OF SKULL between the two cerebral
hemispheres
094
ANATOMY
HEAD AND NECK
SKELETAL
This section—right through the middle of the skull—lets us in on some secrets. We
can clearly appreciate the size of the cranial cavity, which is almost completely filled by
the brain, with just a small gap for membranes, fluid, and blood vessels. Some of those
blood vessels leave deep grooves on the inner surface of the skull: we can trace the
course of the large venous sinuses and the branches of the middle meningeal artery.
We can also see that the skull bones are not solid, but contain trabecular bone (or diploe),
which itself contains red marrow. Some skull bones also contain air spaces, like the
sphenoidal sinus visible here. We can also appreciate the large size of the nasal cavity,
hidden away inside the skull.
Frontal bone
Forms the anterior cranial fossa,
where the frontal lobes of the
brain lie, inside the skull
Frontal sinus
One of the paranasal air sinuses that
drain into the nasal cavity, this is an
air space within the frontal bone
Nasal bone
Pituitary fossa
Fossa is the Latin word for ditch;
the pituitary gland occupies this
small cavity on the upper surface
of the sphenoid bone
Superior nasal concha
Part of the ethmoid bone, which
forms the roof and upper sides of
the nasal cavity
Sphenoidal sinus
Another paranasal air sinus; it
lies within the body of the
sphenoid bone
Anterior nasal crest
Middle nasal concha
Like the superior nasal concha, this
is also part of the ethmoid bone
Inferior nasal concha
A separate bone, attached
to the inner surface of the maxilla;
the conchae increase the surface
area of the nasal cavity
Palatine bone
Joins to the maxillae and forms
the back of the hard palate
Pterygoid process
Sticking down from the greater
wing of the sphenoid bone, theis
process flanks the back of the nasal
cavity and provides attachment for
muscles of the palate and jaw
095
HEAD AND NECK • SKELETAL
Parietal bone
Grooves for arteries
Meningeal arteries
branch on the inside
of the skull and leave
grooves on the bones
Squamous part of
the temporal bone
Squamosal suture
Lambdoid suture
Internal acoustic meatus
Hole in petrous part of the
temporal bone that transmits
both the facial and
vestibulocochlear nerves
Occipital bone
External occipital protuberance
Projection from occipital bone that
gives attachment to the nuchal
ligament of the neck; much more
pronounced in men than in women
Hypoglossal canal
Hole through occipital bone, in
the cranial base, that transmits the
hypoglossal nerve supplying
the tongue muscles
Styloid process
INTERIOR OF SKULL
096 Parietal bone
Frontal bone
ANATOMY Forms joints with the
parietal and sphenoid
HEAD AND NECK bones on the top
SKELETAL and sides of the skull,
and with the maxilla,
In this view of the skull, we can clearly see that it is not one single nasal, lacrimal, and
bone, and we can also see how the various cranial bones fit together ethmoid bones below
to produce the shape we are more familiar with. The butterfly-shaped
sphenoid bone is right in the middle of the action—it forms part
of the skull base, the orbits, and the side-walls of the skull, and it
articulates with many of the other bones of the skull. The temporal
bones also form part of the skull’s base and side walls. The extremely
dense petrous parts of the temporal bones contain and protect the
delicate workings of the ear, including the tiny ossicles (malleus, incus,
and stapes) that transmit vibrations from the eardrum to the inner ear.
Frontal bone
Forms the front
of the skull;
articulates with the
parietal bones at
the coronal suture
Nasal bones
Two bones, attaching
to the frontal bone
above and the maxillae
to the side, form the
bridge of the nose
Maxilla
With the opposite
maxilla forms the
upper jaw and frames
the nose
ARTICULATED VIEW Occipital
bone
Occipital bone Zygomatic bone Parietal bone
Forms the lower Cheek bone, also Forms the roof and
part of the back of lateral border of
side of the skull
the skull the eye socket
Sphenoid
bone
Petrous
part of
temporal
bone
Orbital
plate of
ethmoid
bone
Nasal bone
Lacrimal bone
Orbital surface Zygomatic
of maxilla process
Temporal bone Mastoid Ramus of mandible Zygomatic
Articulates with process bone
the parietal,
sphenoid, and Vomer
occipital bones and Maxilla
contains the ear Articulates with the opposite
maxilla in the midline, with the
apparatus,including nasal, frontal, and lacrimal bones
the ossicles above, and the sphenoid,
ethmoid, and palatine bones
Zygomatic bone
This roughly Alveolar process
triangular bone of maxilla
connects the frontal Projects down from
bone, maxilla, and the maxilla and
forms the sockets
temporal bone for the upper teeth
Angle of mandible
The masseter muscle
attaches down to this angle,
which tends to be slightly
flared outward in men
Body of mandible Alveolar process
The mandible develops
as two separate bones, of mandible
Projects up from the
which fuse in infancy mandible and forms
the sockets for the
lower teeth
DISARTICULATED VIEW 097
MALLEUS STAPES INCUS HEAD AND NECK • SKELETAL
POSTERIOR (BACK) Temporalis TOP Frontal belly of The muscles of the face have very important MUSCULAR HEAD AND NECK 098
occipitofrontalis functions. They open and close the apertures in our
Occipital belly of faces—our eyes, noses, and mouths. But they also ANATOMY
occipitofrontalis Epicranial play an extremely important role in communication,
aponeurosis and this is why these muscles are often known,
Semispinalis capitis collectively, as “the muscles of facial expression.”
Temporalis These muscles are attached to bone at one end
Splenius capitis and skin at the other. It is these muscles that allow
Occipital belly of us to raise our eyebrows in surprise, frown, or knit
Sternocleidomastoid occipitofrontalis our brows in concentration, to scrunch up our
noses in distaste, to smile gently or grin widely, and
Trapezius to pout. As we age, and our skin forms creases and
wrinkles, these reflect the expressions we have used
Levator throughout our lives. The wrinkles and creases lie
scapulae perpendicular to the direction of the underlying
muscle fibers.
Rhomboid
minor
Rhomboid
major
Acromion of
scapula
Spine of
scapula
DEEP SUPERFICIAL
Epicranial aponeurosis
This connects the frontal
and occipital bellies of the
occipitofrontalis muscle
Frontal belly of ANTERIOR (FRONT)
occipitofrontalis
Occipitofrontalis extends
from the eyebrows to
the superior nuchal line on
the back of the skull, and
can raise the eyebrows and
move the scalp
Temporalis Nasalis
One of the four paired The upper part of this nasal
muscles of mastication, muscle compresses the
nose, while the lower part
or chewing; acts to flares the nostrils
close the mouth and
bring the teeth together Levator labii superioris
alaeque nasi
Orbicularis oculi This small muscle with a
These muscle fibers very long name lifts the
encircle the eye and act upper lip and the side of
the nostril to produce an
to close the eye unpleasant sneer
Cartilage of the Levator labii
external nose superioris
Raises the upper lip
Zygomaticus minor
Zygomaticus major
Both the zygomaticus
major and minor attach
from the zygomatic arch
(cheek bone) to the side
of the upper lip, and are
used in smiling