No. 30No. 30
1. Cervical Plexus1. Cervical Plexus
2. Brachial Plexus2. Brachial Plexus
Chapter 3 The Peripheral Nervous Chapter 3 The Peripheral Nervous SystemSystem
Introduction:Introduction: The peripheral nervous system is the nervous structurThe peripheral nervous system is the nervous structur
es outside the brain and spinal cord. It is composed of es outside the brain and spinal cord. It is composed of nerves and ganglia, and usually divided into three pornerves and ganglia, and usually divided into three portions according to their origins and distribution:tions according to their origins and distribution:
(1) Spinal nerves (31 pairs):(1) Spinal nerves (31 pairs): They attach to the spinal cord and make their exit throThey attach to the spinal cord and make their exit thro
ugh the intervertebral foramina.ugh the intervertebral foramina. (2) Cranial nerves (12pairs):(2) Cranial nerves (12pairs): They attach to the brain and make their exit through tThey attach to the brain and make their exit through t
he skull.he skull.
(3) Visceral nerves:(3) Visceral nerves: A further part of the peripheral nervous A further part of the peripheral nervous
system which is not a separate system which is not a separate morphological entity but a grouping of morphological entity but a grouping of special nerve components which travel special nerve components which travel within certain spinal and cranial nerves to within certain spinal and cranial nerves to innervate smooth muscle, cardiac muscle innervate smooth muscle, cardiac muscle and gland, that is the visceral nervous and gland, that is the visceral nervous system.system.
According to the difference of subject According to the difference of subject innervated by the nerves, the peripheral innervated by the nerves, the peripheral nervous system is divided the nervous system is divided the somatic somatic nervesnerves (supply the body surface, bones, (supply the body surface, bones, joints, and skeletal muscle) and joints, and skeletal muscle) and visceral visceral nervesnerves (are distributed in the viscera, (are distributed in the viscera, heart, vessels, and smooth muscles).heart, vessels, and smooth muscles).
In the peripheral nerves (the somatic and In the peripheral nerves (the somatic and visceral nerves), there are two nerve fibers visceral nerves), there are two nerve fibers called called afferent nervesafferent nerves ( (sensory nervessensory nerves)) and and efferent nervesefferent nerves ( (motor nervesmotor nerves).).
The visceral efferent (motor) nerve is also The visceral efferent (motor) nerve is also called the called the vegetative nervous systemvegetative nervous system or or autonomic nervous systemautonomic nervous system and is and is further divided into further divided into sympathetic nervesympathetic nerve and and parasympathetic nerveparasympathetic nerve. .
Section 1 The Spinal NerveSection 1 The Spinal Nerve
Introduction:Introduction: 1. The formation, division, fibrous components of 1. The formation, division, fibrous components of
spinal nervesspinal nerves (1) Formation of the spinal nerves(1) Formation of the spinal nerves The spinal nerves, 31 pairs in number, are formed The spinal nerves, 31 pairs in number, are formed
from the union of ventral (anterior) and dorsal from the union of ventral (anterior) and dorsal (posterior) roots that leave or enter the spinal (posterior) roots that leave or enter the spinal cord.cord.
The The anterior rootanterior root contains motor fibers arising contains motor fibers arising from the large motor cells of the anterior and from the large motor cells of the anterior and lateral horns of the gray matter.lateral horns of the gray matter.
The The posterior rootposterior root contains sensory fibers wh contains sensory fibers which are the central processes of the pseudouniich are the central processes of the pseudounipolar neurons in the spinal ganglion.polar neurons in the spinal ganglion.
So the spinal nerves are mixed nerves.So the spinal nerves are mixed nerves. Spinal ganglionSpinal ganglion:: The The spinal ganglionspinal ganglion contains cell bodies of ps contains cell bodies of ps
eudounipolar neurons, their peripheral proceseudounipolar neurons, their peripheral processes are united with the anterior root to form thses are united with the anterior root to form the spinal nerve at the intervertebral foramen.e spinal nerve at the intervertebral foramen.
(2) The division of spinal nerves(2) The division of spinal nerves There are 31 pairs of spinal nerves, including 8 pairs of There are 31 pairs of spinal nerves, including 8 pairs of
cervical, 12 pairs of thoracic, 5 pairs of lumbar, 5 pairs cervical, 12 pairs of thoracic, 5 pairs of lumbar, 5 pairs of sacral, and 1 pair of coccygeal nerves.of sacral, and 1 pair of coccygeal nerves.
The spinal nerves leave the vertebral canal by passing The spinal nerves leave the vertebral canal by passing through the through the intervertebral foraminaintervertebral foramina..
All spinal nerves emerge from the intervertebral foramAll spinal nerves emerge from the intervertebral foramina between adjoining vertebrae, but the 1st cervical nina between adjoining vertebrae, but the 1st cervical nerve exits between the occipital bone and the atlas.erve exits between the occipital bone and the atlas.
The 8th cervical nerve emerges between the seventh cThe 8th cervical nerve emerges between the seventh cervical and the first thoracic vertebrae.ervical and the first thoracic vertebrae.
The first four of the sacral nerves make their exit throuThe first four of the sacral nerves make their exit through foramina in the sacrum, the fifth and the coccygeal gh foramina in the sacrum, the fifth and the coccygeal nerves emerge from the sacral hiatus.nerves emerge from the sacral hiatus.
(3) Fibrous components of spinal nerve(3) Fibrous components of spinal nerve The spinal nerves consist of four components:The spinal nerves consist of four components: ① ① The somatic sensory (afferent) fibersThe somatic sensory (afferent) fibers The fibers come from the The fibers come from the pseudounipolar neuronspseudounipolar neurons in t in t
he spinal ganglion. The central processes of pseudounhe spinal ganglion. The central processes of pseudounipolar neurons constitute the posterior roots of spinal ipolar neurons constitute the posterior roots of spinal nerves to go into the spinal cord, while their peripheranerves to go into the spinal cord, while their peripheral processes enter into the spinal nerves to distribute tl processes enter into the spinal nerves to distribute the skin, skeletal muscles, muscular tendon, and the johe skin, skeletal muscles, muscular tendon, and the joints of the trunk and limbs, conducting impulses of thints of the trunk and limbs, conducting impulses of the superficial sensations of skin (sensations of pain, thee superficial sensations of skin (sensations of pain, thermal and tactile) and the deep (proprioceptive) sensatrmal and tactile) and the deep (proprioceptive) sensations of muscles, tendon, and joints (sensations of the ions of muscles, tendon, and joints (sensations of the body posture, movement, vibration) into the center.body posture, movement, vibration) into the center.
② ② The visceral sensory (afferent) fibersThe visceral sensory (afferent) fibers They are also from the They are also from the pseudounipolar neuronspseudounipolar neurons in the in the
spinal ganglion. The central processes form the posterspinal ganglion. The central processes form the posterior roots of the spinal nerves to go into the spinal cord,ior roots of the spinal nerves to go into the spinal cord, while their peripheral processes distribute the viscera, while their peripheral processes distribute the viscera, heart, blood vessels, and glands. heart, blood vessels, and glands.
③ ③ The somatic motor (efferent) fibersThe somatic motor (efferent) fibers The somatic motor fibers coming from the anterior hoThe somatic motor fibers coming from the anterior ho
rn of spinal cord, distribute to the skeletal muscles to rn of spinal cord, distribute to the skeletal muscles to control their voluntary movement.control their voluntary movement.
④ ④ The visceral motor (efferent) fibersThe visceral motor (efferent) fibers The visceral motor fibers coming from the lateThe visceral motor fibers coming from the late
ral horn in the thoracolumbar segments (sympral horn in the thoracolumbar segments (sympathetic nerve center) and sacral parasympatheathetic nerve center) and sacral parasympathetic nucleus (parasympathetic nerve center) of tic nucleus (parasympathetic nerve center) of spinal cord, distribute the viscera, heart and blspinal cord, distribute the viscera, heart and blood vessels, and glands to innervate the moveood vessels, and glands to innervate the movements of cardiac and smooth muscles, and to ments of cardiac and smooth muscles, and to control the secretion of glands.control the secretion of glands.
2. Branches of the spinal nerves2. Branches of the spinal nerves Immediately after leaving the foramen, the spinal nervImmediately after leaving the foramen, the spinal nerv
e is divided into:e is divided into: ① ①The The dorsal (posterior) branchdorsal (posterior) branch: for the supply of mus: for the supply of mus
cles and skin of the posterior part of the body. The poscles and skin of the posterior part of the body. The posterior branches are generally smaller than the anterior,terior branches are generally smaller than the anterior, but the posterior branch of the second cervical nerve but the posterior branch of the second cervical nerve is larger, its cuteneous branch called the is larger, its cuteneous branch called the greater occigreater occipital nervepital nerve, supplies the skin of the occiput., supplies the skin of the occiput.
② ②The The anterior branchanterior branch: for the supply of structures of t: for the supply of structures of the limbs, the lateral and ventral trunk.he limbs, the lateral and ventral trunk.
③ ③The The meningeal branchmeningeal branch: supplies the dura m: supplies the dura matter.atter.
④ ④The The communicating branchescommunicating branches: connects wit: connects with the sympathetic trunk.h the sympathetic trunk.
Except for the anterior branches of thoracic neExcept for the anterior branches of thoracic nerves which are quite separated from each otherves which are quite separated from each other, the anterior branches of other spinal nerves r, the anterior branches of other spinal nerves form intricate plexus before supplying a part oform intricate plexus before supplying a part of body.f body.
They are named the cervical plexus, the brachiThey are named the cervical plexus, the brachial plexus, the lumbar plexus and the sacral pleal plexus, the lumbar plexus and the sacral plexus.xus.
ⅠⅠ. The Cervical Plexus. The Cervical Plexus
Ⅰ Ⅰ) The Formation of Cervical Plexus) The Formation of Cervical Plexus It is formed by the anterior branches of the fouIt is formed by the anterior branches of the fou
r upper cervical nerves (C1-4).r upper cervical nerves (C1-4). Ⅱ Ⅱ) Location of Cervical Plexus) Location of Cervical Plexus It is situated deeply in the upper part of the neIt is situated deeply in the upper part of the ne
ck, rested on the levator scapulae and scalenuck, rested on the levator scapulae and scalenus medius and is covered by the sternocleiodms medius and is covered by the sternocleiodmastoid.astoid.
Ⅲ Ⅲ) The Branches of Cervical Plexus) The Branches of Cervical Plexus Its branches may be divided into two groups, sIts branches may be divided into two groups, s
uperficial and deep.uperficial and deep.
1. The superficial branches1. The superficial branches They emerge near the middle of the posterior border They emerge near the middle of the posterior border
of the sternocleidomastoid and have fan-shaped distriof the sternocleidomastoid and have fan-shaped distribution.bution.
1) The 1) The lesser occipitallesser occipital nervenerve(C1). It is distributed to th(C1). It is distributed to the skin of occiput and behind the auricle.e skin of occiput and behind the auricle.
2) The 2) The greater auriculargreater auricular nervenerve(C2-3). It supplies much (C2-3). It supplies much of the external ear and some skin around the auricle.of the external ear and some skin around the auricle.
3) The 3) The transverse nerve oftransverse nerve of neckneck(C2-3). It is distributed (C2-3). It is distributed to the skin of the anterior part of the neck.to the skin of the anterior part of the neck.
4) The 4) The supraclavicular nervessupraclavicular nerves(C2-4). They are distribu(C2-4). They are distributed to the skin at the upper portion of the chest, the bted to the skin at the upper portion of the chest, the base of the neck and the shoulder.ase of the neck and the shoulder.
2. The deep branches2. The deep branches The The phrenic nervephrenic nerve (C (C3-53-5)) It descends to the root of the neck, running obIt descends to the root of the neck, running ob
liquely across the front of the scalenus anterioliquely across the front of the scalenus anterior, then passes between the subclavian artery ar, then passes between the subclavian artery and vein to enter the chest. Within the chest it dnd vein to enter the chest. Within the chest it descends in front of the root of the lung betweeescends in front of the root of the lung between the pericardium and the mediastinal pleura tn the pericardium and the mediastinal pleura to the diaphragm.o the diaphragm.
The motor fibers supply the diaphragm, the seThe motor fibers supply the diaphragm, the sensory fibers are distributed to the diaphragmansory fibers are distributed to the diaphragmatic peritoneum, the diaphragmatic and mediastic peritoneum, the diaphragmatic and mediastinal pleurae and the pericardium. The sensory tinal pleurae and the pericardium. The sensory fibers of the right phrenic nerve is also distribufibers of the right phrenic nerve is also distributed to the liver, the gallbladder and the biliary ted to the liver, the gallbladder and the biliary system.system.
ⅡⅡ. The Brachial Plexus. The Brachial Plexus
Ⅰ Ⅰ) The Formation and Location of Brachial Plexus) The Formation and Location of Brachial Plexus The brachial plexus is formed by the union of the anteThe brachial plexus is formed by the union of the ante
rior branches of the four lower cervical nerves (C5-8) arior branches of the four lower cervical nerves (C5-8) and great part of the anterior branch of the first thoracind great part of the anterior branch of the first thoracic nerve (T1).c nerve (T1).
It extends from the lower part of the side of the neck tIt extends from the lower part of the side of the neck to the axilla.o the axilla.
Three trunksThree trunks: between the scalenus anterior and scale: between the scalenus anterior and scalenus medium.nus medium.
Superior trunk (C5-6),Superior trunk (C5-6), Middle trunk (C7),Middle trunk (C7), Inferior trunk (C8, T1).Inferior trunk (C8, T1).
DivisionsDivisions: beneath the clavicle, each of these tr: beneath the clavicle, each of these trunks is divided into two divisions—an anterior unks is divided into two divisions—an anterior and posterior divisions.and posterior divisions.
↓↓ CordsCords: in the axilla.: in the axilla. Lateral cord: the anterior divisions of the supeLateral cord: the anterior divisions of the supe
rior and middle trunks unite to form.rior and middle trunks unite to form. Medial cord: the anterior division of the inferioMedial cord: the anterior division of the inferio
r trunk.r trunk. Posterior cord: the posterior divisions of all thPosterior cord: the posterior divisions of all th
e three trunks to from.e three trunks to from.
ⅡⅡ) The Branches of Brachial Plexus) The Branches of Brachial Plexus
1. The branches above the clavicle1. The branches above the clavicle 1) The 1) The long thoracic nervelong thoracic nerve: supplies the serrat: supplies the serrat
us anterior→”winging of the scapula”.us anterior→”winging of the scapula”. 2) The 2) The suprascapular nervesuprascapular nerve: supplies the supr: supplies the supr
aspinatus and the infraspinatus.aspinatus and the infraspinatus. 3) The 3) The dorsal scapular nervedorsal scapular nerve: supplies the leva: supplies the leva
tor scapulae and rhomboideus.tor scapulae and rhomboideus.
2. The branches below the clavicle2. The branches below the clavicle 1) The 1) The subscapular nervesubscapular nerve (C5-7) (C5-7) It originates from the posterior cord of the brachial plIt originates from the posterior cord of the brachial pl
exus, supplies the subscapularis and teres major.exus, supplies the subscapularis and teres major. 2) The 2) The thoracodorsal nervethoracodorsal nerve (C6-8) (C6-8) It arises from the posterior cord of the brachial plexus, It arises from the posterior cord of the brachial plexus,
supplies the latissimus dorsi.supplies the latissimus dorsi. 3) The 3) The laterallateral andand medial pectoral nervesmedial pectoral nerves (anterior th (anterior th
oracic nerves) (C5-T1)oracic nerves) (C5-T1) They arise from the lateral and medial cords and suppThey arise from the lateral and medial cords and supp
ly the pectoralis major and pectoralis minor.ly the pectoralis major and pectoralis minor. 4) The 4) The axillary nerveaxillary nerve (C5-6) (C5-6)
ArisionArision:: It arises from the posterior cord.It arises from the posterior cord. RouteRoute:: It passes backward with the posterior humeral circumflex vIt passes backward with the posterior humeral circumflex v
essels through the quadrangular space and winds round thessels through the quadrangular space and winds round the surgical neck of the humerus to reach the deltoid muscle.e surgical neck of the humerus to reach the deltoid muscle.
Branches and their distributionBranches and their distribution:: Muscular branches supplies the deltoid and teres major, anMuscular branches supplies the deltoid and teres major, an
d cutaneous branch to the skin over the deltoid.d cutaneous branch to the skin over the deltoid. Clinical significanceClinical significance:: This nerve may be injured in fracture of the humeral neck or This nerve may be injured in fracture of the humeral neck or
in dislocation of the shoulder joint.in dislocation of the shoulder joint. The deltoid is paralyzed and wasting.The deltoid is paralyzed and wasting. A small patch of anesthesia over this muscle may also occur.A small patch of anesthesia over this muscle may also occur.
5) The 5) The musculocutaneous nervemusculocutaneous nerve (C5-7) (C5-7) It arises from the lateral cord of the brachial plexus anIt arises from the lateral cord of the brachial plexus an
d perforates through the coracobrachialis, then desced perforates through the coracobrachialis, then descends between the biceps brachii and the brachialis and nds between the biceps brachii and the brachialis and gives off some branches to supply these three muscles.gives off some branches to supply these three muscles.
A little above the elbow, it pierces the deep fascia betA little above the elbow, it pierces the deep fascia between the tendon of the biceps and the brachioradialis ween the tendon of the biceps and the brachioradialis as the as the lateral antebrachial cutaneouslateral antebrachial cutaneous nerve which s nerve which supplies the skin of the lateral side of the forearm.upplies the skin of the lateral side of the forearm.
6) The 6) The median nervemedian nerve (C6-8, T1) (C6-8, T1) ArisionArision:: It arises by two roots, one from the lateral and anotheIt arises by two roots, one from the lateral and anothe
r from the medial cord of the brachial plexus, which er from the medial cord of the brachial plexus, which embrace the axillary artery and unite each other in fronmbrace the axillary artery and unite each other in front or on the lateral side of the vessel.t or on the lateral side of the vessel.
RouteRoute:: It descends along the medial side of the biceps with thIt descends along the medial side of the biceps with th
e brachial artery.e brachial artery. It is lateral to the brachial artery—in the upper part of It is lateral to the brachial artery—in the upper part of
the arm.the arm. It crosses the brachial artery anteriorly and posteriorlIt crosses the brachial artery anteriorly and posteriorl
y at the middle part of the arm.y at the middle part of the arm. It lies on the medial side of the artery to the cubital fosIt lies on the medial side of the artery to the cubital fos
sa.sa.
It enters the forearm, by passing between the tIt enters the forearm, by passing between the two heads of the pronator teres, and descends wo heads of the pronator teres, and descends deep to the flexor digitorum superficialis, lying deep to the flexor digitorum superficialis, lying on the flexor digitorum profundus, to the wrist,on the flexor digitorum profundus, to the wrist, lying between the tendons of the flexor carpi r lying between the tendons of the flexor carpi radialis and palmaris longus, then passes beneadialis and palmaris longus, then passes beneath the flexor retinaculum into the palm of the ath the flexor retinaculum into the palm of the hand and is covered by the palmar aponeurosihand and is covered by the palmar aponeurosis.s.
Branches and their distributionBranches and their distribution:: ① ①It has no branches in the arm.It has no branches in the arm. ② ②In the forearm: it supply the both pronators In the forearm: it supply the both pronators
(protonator teres and pronator quadatus) and (protonator teres and pronator quadatus) and most of the flexor muscles (flexor carpi radialis,most of the flexor muscles (flexor carpi radialis, palmaris longus, flexor digiturum superficialis, palmaris longus, flexor digiturum superficialis, flexor pollicis longus and lateral half of the fle flexor pollicis longus and lateral half of the flexor digitorum) except the brachioradialis, the fxor digitorum) except the brachioradialis, the flexor carpi ulnaris and the medial half of the fllexor carpi ulnaris and the medial half of the flexor digitorum profundus.exor digitorum profundus.
③ ③Before reaching the flexor retinaculum, it gives rise tBefore reaching the flexor retinaculum, it gives rise to a small o a small palmar cutaneous branchpalmar cutaneous branch to the skin of the to the skin of the thenar and central part of the palm.thenar and central part of the palm.
④ ④In the palm, it divides into a In the palm, it divides into a recurrent branchrecurrent branch and th and three ree common palmar digital nervescommon palmar digital nerves..
The recurrent branch innervates the thenar muscles eThe recurrent branch innervates the thenar muscles except for the adductor pollicis.xcept for the adductor pollicis.
Each of common palmar digital nerves divides into prEach of common palmar digital nerves divides into proper oper palmar digital nervespalmar digital nerves for the skin of the palmar for the skin of the palmar aspect of the thumb, second, third and the lateral half aspect of the thumb, second, third and the lateral half of the fourth fingers, as well as the skin on the dorsum of the fourth fingers, as well as the skin on the dorsum of the middle and terminal phalanges.of the middle and terminal phalanges.
⑤⑤It also contributes muscular branches to the first anIt also contributes muscular branches to the first and second lumbricales.d second lumbricales.
Clinical significanceClinical significance:: An injury to the median nerve in the forearm can resulAn injury to the median nerve in the forearm can resul
t in:t in: ① ① A loss of pronation of the forearm, flexion of the secA loss of pronation of the forearm, flexion of the sec
ond, the third fingers and the distal phalanx of the thuond, the third fingers and the distal phalanx of the thumb and opposition of the thumb.mb and opposition of the thumb.
② ② Wrist flexion is severely affected.Wrist flexion is severely affected. ③ ③ The thenar muscles are paralyzed, so that the thumThe thenar muscles are paralyzed, so that the thum
b becomes to lie in the same plane as the other digits, b becomes to lie in the same plane as the other digits, it is just an “ape-like” hand.it is just an “ape-like” hand.
④ ④ There is also a loss or weakness of sensation from thThere is also a loss or weakness of sensation from the skin of the radial part of the palmar surface of the the skin of the radial part of the palmar surface of the thumb, index, middle and radial half of the ring finger.umb, index, middle and radial half of the ring finger.
7) The 7) The ulnar nerveulnar nerve (C7-T1) (C7-T1) ArisionArision:: It arises from the medial cord of the brachial plexus.It arises from the medial cord of the brachial plexus. RouteRoute:: At first it lies to the medial side of the brachial artery, At first it lies to the medial side of the brachial artery,
about the middle of the arm it pierces the medial interabout the middle of the arm it pierces the medial intermuscular septum and descends to pass along the gromuscular septum and descends to pass along the groove between the medial epicondyle of humerus and tove between the medial epicondyle of humerus and the olecranon, here the ulnar nerve is superficial and ehe olecranon, here the ulnar nerve is superficial and easily palpable against the bone, so that, it is easily injuasily palpable against the bone, so that, it is easily injured. It enters the forearm between the heads of the flered. It enters the forearm between the heads of the flexor carpi ulnaris, and runs downward deep to this muxor carpi ulnaris, and runs downward deep to this muscle on the flexor digitorum profundus with the ulnar scle on the flexor digitorum profundus with the ulnar artery at its medial side to the wrist.artery at its medial side to the wrist.
Branches and their distributionBranches and their distribution:: ① ① In the arm, the ulnar nerve has no branch.In the arm, the ulnar nerve has no branch. ② ② At the wrist, it crosses the anterior surface of the flexAt the wrist, it crosses the anterior surface of the flex
or retinaculum and immediately divides into a superfior retinaculum and immediately divides into a superficial branch and a deep palmar branch.cial branch and a deep palmar branch.
The The superficial branchsuperficial branch is cutaneous branch, it provid is cutaneous branch, it provides:es:
*A *A proper digital nerveproper digital nerve to the skin of ulnar side of the to the skin of ulnar side of the little finger and the skin of hypothenar.little finger and the skin of hypothenar.
*A *A common palmer digital nervecommon palmer digital nerve divides into two pr divides into two proper palmardigital nerves for the skin of contiguous sioper palmardigital nerves for the skin of contiguous sides of fourth and fifth fingers.des of fourth and fifth fingers.
The The deep palmar branchdeep palmar branch is muscular branch, is muscular branch, it supplies the muscles of hypothenar, the thirit supplies the muscles of hypothenar, the third and the fourth lumbricales, the adductor pold and the fourth lumbricales, the adductor pollicis and interossei.licis and interossei.
③ ③ About 5 cm above the wrist, it gives off a About 5 cm above the wrist, it gives off a dordorsalsal branchbranch, distribute to the ulnar half of the d, distribute to the ulnar half of the dorsum of the hand and the posterior surface of orsum of the hand and the posterior surface of the ulnar one and half fingers.the ulnar one and half fingers.
Clinical significanceClinical significance:: Ulnar nerve may be damaged at the elbow or the wrist.Ulnar nerve may be damaged at the elbow or the wrist.
It results in: It results in: ① ① Interfering with the flexion of the ring and little fingeInterfering with the flexion of the ring and little finge
rs, metacarpophalangeal joints.rs, metacarpophalangeal joints. ② ② The extension of the interphalangeal joints, adductiThe extension of the interphalangeal joints, adducti
on of the thumb is lost.on of the thumb is lost. ③ ③ There is also a loss of abduction and adduction of thThere is also a loss of abduction and adduction of th
e fingers.e fingers. ④ ④ The hand is known as “clawhand”.The hand is known as “clawhand”. ⑤ ⑤ The sensation from the skin of the hypothenar and tThe sensation from the skin of the hypothenar and t
he little finger is lost.he little finger is lost.
8) The 8) The radial nerveradial nerve (C5-T1) (C5-T1) ArisionArision:: It is the continuation of the posterior cord.It is the continuation of the posterior cord. RouteRoute:: In the axilla, it is placed behind the axillary artery.In the axilla, it is placed behind the axillary artery. Then it runs between the lateral and medial heads of tThen it runs between the lateral and medial heads of t
he triceps brachii, and passes along the radial groove.he triceps brachii, and passes along the radial groove. When it reaches the lower one third of the humerus, tWhen it reaches the lower one third of the humerus, t
he radial nerve pierces the lateral intermuscular septuhe radial nerve pierces the lateral intermuscular septum and continues inferiorly between the brachialis and m and continues inferiorly between the brachialis and brachioradialis at the level of the lateral epicondyle of brachioradialis at the level of the lateral epicondyle of the humerus, where it divides into deep and superficiathe humerus, where it divides into deep and superficial branches.l branches.
Branches and their distributionBranches and their distribution::
① ① Superficial branchSuperficial branch:: At about the junction of the middle and At about the junction of the middle and
lower one third of the forearm, it continues lower one third of the forearm, it continues downwards to the dorsum of the hand. downwards to the dorsum of the hand. Here it distributes to the skin on the radial Here it distributes to the skin on the radial side of the dorsum of the hand, and on the side of the dorsum of the hand, and on the proximal digits of the lateral two and half proximal digits of the lateral two and half fingers.fingers.
② ② Deep branchDeep branch:: It pierces through the supinator, curves arounIt pierces through the supinator, curves aroun
d the lateral side of the radius to enter the posd the lateral side of the radius to enter the posterior fascial compartment of the forearm.terior fascial compartment of the forearm.
It distributes the brachioradialis and the extenIt distributes the brachioradialis and the extensors of the forearm.sors of the forearm.
In the arm, the radial nerve also supplies the trIn the arm, the radial nerve also supplies the triceps brachii and the skin on the dorsum of thiceps brachii and the skin on the dorsum of the arm.e arm.
Clinical significanceClinical significance:: Injury to the radial nerve in the upper or middlInjury to the radial nerve in the upper or middl
e part of the arm results in:e part of the arm results in: ① ① The paralysis of the triceps brachii, brachiorThe paralysis of the triceps brachii, brachior
adialis, supinator and extensors of the wrist, tadialis, supinator and extensors of the wrist, thumb and fingers.humb and fingers.
② ② The “Wristdrop”.The “Wristdrop”. ③ ③ Loss of sensation in the areas of skin supplieLoss of sensation in the areas of skin supplie
d by this nerve.d by this nerve.
