Download The Spinal Nerves

The Spinal Nerves
山东大学医学院 解剖教研室
李振华
General description
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31 pairs spinal nerves:
8 cervical, 12 thoracic, 5 lumbar, 5
sacral, and 1 coccygeal nerve.
Formation: each spinal nerve is
formed by union of anterior and
posterior roots at intervertebral
foramen
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The anterior root－contains motor
fibers for skeletal muscles. Those from
T1 to L2 contain sympathetic fibers; S2
to S4 also contain parasympathetic
fibers.
The posterior root－contains sensory
fibers whose cell bodies are in the
spinal ganglion.
Functional components
 Somatic efferent nerve fibers (SE): fibers that transmit motor
impulses from spinal cord to skeletal muscles.
 Visceral efferent nerve fibers (VE): fibers that transmit motor
impulses from spinal cord to smooth muscles, cardiac muscle and
glands.
 Somatic afferent nerve fibers (SA): fibers that transmit
exteroceptive and proprioceptive impulses from body to spinal cord
 Visceral afferent nerve fibers (VA): fibers that transmit
interoceptive impulses from the viscera to spinal cord
Branches of spinal nerves
 Anterior branch: largest , innervates anterolateral body wall and limbs，
the great nerve plexus, e.g. the cervical, brachial, lumbar, and sacral,
are formed by anterior rami
 Posterior branch: innervates the back of the trunk
 Communicating branch: connect the spinal nerve to the sympathetic
trunk
 Meningeal branch: re-enters vertebral canal through intervertebral
foramen to dura mater
Cervical plexus 颈丛
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Formation: formed by
anterior rami of C1-C4 spinal
nerves
Position: lies in front of the
origin of levator scapulae and
scalenus medius and deep to
the superior part of the
sternocleidomastoid
Branches
 Cutaneous branches:
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Lesser occipital
Great auricular
Transverse nerve of neck
Supraclavicular nerves
Emerge around middle of
posterior border of
sternocleidomastoid, to
supply skin of neck and
scalp between auricle and
external occipital
protuberance
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Muscular branches: supply
the deep muscles of neck
Phrenic nerve (anterior rami of
C3-C5) to diaphragm (motor
and sensory):
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Descends over scalenus
anterior to enter thorax
Accompanied by
pericardiophrenic vessels and
passes anterior to lung roots
between mediastinal pleura and
pericardium to supply motor
and sensory innervation to
diaphragm
Sensory fibers supply to
pleurae, pericardium and
peritoneum of diaphragm;
usually right phrenic nerve may
be distributed on live,
gallbladder and biliary system.
Brachial plexus 臂丛
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Formation:
Formed by anterior rami
of C5-C8 and T1 spinal
nerves
Position:
Passes through the
scalene fissure to
posterosuperior of
subclavian artery, then
enters the axilla to form
three cords
Main branche
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Musculocutaneous
nerve
Distribution: Biceps
brachii, brachalis and
coracobrachialis ‘BBC
nerve’; skin on anterior
aspect of forearm
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Median nerve
Distribution: Flexor of
forearm except brachioradialis,
flexor carpi ulnaris and ulnar
half of flexor digitorum
profundus, thenar except
adductor pollicis, first two
lumbricals; skin of thenar,
central part of palm, palmar
aspect of radial three and onehalf fingers, including middle
and distal fingers on dorsum
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Ulnar nerve
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Distribution: Flexor
carpi ulnaris, ulnar half of
flexor digitorum
profundus, hypothenar
muscles, interossei, 3rd
and 4th lumbricals and
adductor pollicis; skin of
hypothenar, palmar
surface of ulnar one and
one-half fingers, ulnar
half of dorsum of hand,
posterior aspect of ulnar
two and one-half fingers
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Injury: clawhand
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Radial
Distribution: Extensor
muscles of arm and
forearm, brachioradialis;
skin on back of arm,
forearm, and radial side
of dorsum of hand and
radial two and one-half
fingers
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Axillary 腋神经
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Distribution:
Deltoid and teres
minor muscle; skin
over deltoid and upper
posterior aspect of
arm
Injury: result in deltoid
andteres minor
paralysis (loss of
shoulser abdution and
weel external rotation)
with loss of sensation
over the deltoid
Anterior branches of thoracic nerves
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Intercostal nerves (anterior
rami of T1- T11)
Subcostal nerve (anterior
ramus of T12)
Distribution: distributed to
intercostales and anterolateral
abdominal muscles, skin of
thoracic and abdominal wall,
parietal pleura and peritoneum
T2 Sternal angle
T4 Nipple
T6 Xiphoid process
T8 Costal arch
T10 Umbilicus
T12 Midpoint between
umbilicus and symphysis pubis
Lumbar plexus
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Formation: formed by
anterior rami of L1-L3, a
part of anterior rami of
T12and L4
Position: lies within
substance of psoas major
Branches
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Iliohypogastric
Ilioinguinal
Lateral femoral cutaneous
Femoral
Obturator
Genitofemoral
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Femoral
Runs downward and
laterally between psoas and
iliacus, passes deep to
inguinal ligament; supplies
anterior thigh muscles
(quadriceps, sartorius and
pectineus), hip and knee
joint, and skin on
anteromedial side of thigh,
saphenous nerve is
distributed to skin of medial
side of leg and foot
Obturator
Enters thigh through
obturator foramen; supplies
medial group of muscles of
thigh, obturator externus,
and skin of medial side of
thigh
Sacral plexus 骶丛
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Formation: formed by
anterior rami of L4 and
L5 spinal nerves (the
lumbrosacral trunk) and
anterior rami of sacral
and coccygeal nerves
Position: lies in pelvic
cavity, anterior to
sacrum and piriformis
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Branches
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Superior gluteal
Pudendal
Posterior femoral cutaneou
Sciatic
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Sciatic nerve
Leaves pelvis through infrapiriform
foramen to enter gluteal region, runs
inferiorly laterally deep to gluteus
maximus, passing midway between
the greater trochanter of femur and
ischial tuberosity to back of thigh,
lying deep to long head of biceps
femoris, normally divided into tibial
and common peroneal nerves just
above popliteal fossa; innervates
semitendinosus, semimembranosus
and biceps femoris and has articular
branches to hip and knee joints
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Tibial nerve
Decends through popliteal
fossa and lies on popliteus;
then runs inferiorly with
posterior tibial vessels and
terminates beneath flexor
retinaculum by dividing
into medial and lateral
plantar nerves; supplies
posterior muscles of leg
and knee joint
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Common peroneal nerve
Arises at apex of popliteal fossa and follows
medial border of biceps femoris and its tendon;
passes over posterior aspect of head of fibula and
then winds around neck of fibula, deep to peroneus
longus, where it divides into deep and superficial
peroneal nerves
Deep peroneal nerve
Arises between peroneus longus and neck of fibula;
descends on interosseous membrane and enters
dorsum of foot; supplies anterior muscles of leg,
and skin of first interdigital cleft
Superficial peroneal
Arises between peroneus longus and neck of fibula
and descends in lateral compartment of leg;
supplies peroneus longus and brevis and skin on
anterior surface of leg and dorsum of foot
Superficial peroneal
Deep peroneal