Axillary & Median Axillary & Median NervesNerves

Prof. Saeed Makarem & Dr. Zeenat Zaidi

ObjectivesObjectives

At the end of the lecture, students should be able to:

• Describe the origin, course, relations, branches and distribution of the axillary & median nerves

• Describe the common causes and affects of injury to the axillary and median nerves

Both axillary & median nerves are branches of Both axillary & median nerves are branches of the the brachial plexusbrachial plexus

Both axillary & median nerves are branches of Both axillary & median nerves are branches of the the brachial plexusbrachial plexus

Origin:Origin: (C 5 & 6). (C 5 & 6).• Posterior cord of brachial Posterior cord of brachial

plexusplexusCourse:Course: • It passes inferiorly and It passes inferiorly and

laterally along the posterior laterally along the posterior wall of the axillawall of the axilla

• Then, it passes posteriorly Then, it passes posteriorly around the surgical neck of around the surgical neck of the humerus. the humerus.

• It is accompanied by the It is accompanied by the posterior circumflex humeral posterior circumflex humeral artery. artery.

Axillary NerveAxillary Nerve

Branches:Branches:• MotorMotor to the to the deltoiddeltoid and and

teres minor teres minor muscles.muscles.• SensorySensory: : Superior lateral Superior lateral

cutaneous nerve of arm cutaneous nerve of arm that loops around the that loops around the posterior margin of the posterior margin of the deltoid muscle to innervate deltoid muscle to innervate skin in that region. skin in that region.

• The axillary nerve is usually injured due to: 1. Fracture of

surgical neck of the humerus.

2. Downward dislocation of the shoulder joint

3. Compression. from the incorrect use of crutches.

Axillary Nerve Lesion: CausesAxillary Nerve Lesion: Causes11

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Motor: Motor: • Paralysis of the Paralysis of the deltoiddeltoid and and

teres minor teres minor muscles. muscles. • Impaired abduction of the Impaired abduction of the

shoulder (30-90˚). shoulder (30-90˚). • The paralyzed The paralyzed deltoid wastes deltoid wastes

rapidly. rapidly. • As the deltoid atrophies, the As the deltoid atrophies, the

rounded contour of the rounded contour of the shoulder is flattened shoulder is flattened compared compared to the uninjured side. to the uninjured side.

Sensory:Sensory: Loss of sensation Loss of sensation over over the lateral side of the proximal the lateral side of the proximal part of the arm. part of the arm.

Axillary Nerve Lesion: EffectsAxillary Nerve Lesion: Effects

Median NerveMedian Nerve

Origin: Origin: (C5,6,7, 8, T1)• The median nerve is

formed anterior to the third part of the axillary artery by the union of lateral and medial roots originating from the lateral and medial cords of the brachial plexus.

• Enters the arm from the Enters the arm from the axilla at the inferior margin axilla at the inferior margin of the teres major muscle.of the teres major muscle.

• Passes vertically down the Passes vertically down the medial side of the arm in the medial side of the arm in the anterior compartment and is anterior compartment and is related to the related to the brachial artery brachial artery throughout its course: throughout its course: • in proximal regionin proximal region, it lies , it lies

immediately lateral to immediately lateral to the brachial artery; the brachial artery;

• in more distal regionin more distal region,it ,it crosses to the medial side crosses to the medial side of the brachial artery and of the brachial artery and lies anterior to the elbow lies anterior to the elbow joint. joint.

Median Nerve in the Arm Median Nerve in the Arm

The median nerve has The median nerve has NO major branches in NO major branches in the armthe arm, but a branch to one of the muscles of , but a branch to one of the muscles of the forearm, the the forearm, the pronator teres pronator teres muscle, may muscle, may originate from the nerve immediately originate from the nerve immediately proximal to the elbow joint. proximal to the elbow joint.

• Median nerve passes Median nerve passes into the forearm anterior into the forearm anterior to elbow joint, where to elbow joint, where branches innervate branches innervate most most of the muscles of the muscles in the in the anterior compartment of anterior compartment of the forearm the forearm ((exceptexcept for for the the flexor carpi ulnaris flexor carpi ulnaris muscle and the muscle and the medial medial half of the flexor half of the flexor digitorum profundusdigitorum profundus, , which are innervated by which are innervated by the the ulnar nerveulnar nerve). ).

Median Nerve in the Forearm

• The median nerve continues into The median nerve continues into the hand by passing the hand by passing deep to the deep to the flexor retinaculumflexor retinaculum..

• It innervates: It innervates: • Three thenarThree thenar muscles muscles

associated with the thumb associated with the thumb • Lateral 2 lumbricalLateral 2 lumbrical muscles muscles

associated with movement of associated with movement of the index and middle fingers; the index and middle fingers; and and

• Skin over the palmar surface Skin over the palmar surface of the lateral three and one-of the lateral three and one-half digitshalf digits and and over the over the lateral side of the palm and lateral side of the palm and middle of the wrist. middle of the wrist.

Median Nerve in the Hand

• Injury of median nerve at different levels cause Injury of median nerve at different levels cause different syndromes.different syndromes.

• In the arm and forearm the median nerve is usually not In the arm and forearm the median nerve is usually not injured by trauma because of its relatively deep injured by trauma because of its relatively deep position. position.

• Median nerve can be damagedMedian nerve can be damaged:: In the elbow regionIn the elbow region At the wrist above the flexor retinaculumAt the wrist above the flexor retinaculum In the carpal tunnelIn the carpal tunnel

Median Nerve LesionMedian Nerve Lesion

• The most serious disability of The most serious disability of median nerve injuries is the:median nerve injuries is the:Loss of opposition of the Loss of opposition of the

thumbthumb. The delicate pincer-. The delicate pincer-like action is not possiblelike action is not possible

Loss of sensation Loss of sensation from the from the thumb and lateral 2½ thumb and lateral 2½ fingers & lateral ⅔ of the fingers & lateral ⅔ of the palmpalm

• Damaged in supracondylar Damaged in supracondylar fracture of humerusfracture of humerus

• Muscles affected are: Muscles affected are: Pronator muscles of the Pronator muscles of the

forearmforearmAll long flexors of the All long flexors of the

wrist and fingers wrist and fingers exceptexcept flexor carpi ulnaris flexor carpi ulnaris and and medial half of flexor medial half of flexor digitorum profundusdigitorum profundus

Median Nerve Lesion in the Elbow RegionMedian Nerve Lesion in the Elbow Region

Motor EffectsMotor Effects: : • Loss of Loss of pronationpronation. Hand is kept in . Hand is kept in

supine positionsupine position• Wrist shows weak flexion, and Wrist shows weak flexion, and

ulnar deviationulnar deviation• Loss ofLoss of flexion flexion on the on the

interphalangeal joints of the index interphalangeal joints of the index and middle fingersand middle fingers

• WeakWeak flexion of ring and little flexion of ring and little fingerfinger

• ThumbThumb is adducted and laterally is adducted and laterally rotated, with rotated, with loss of flexion loss of flexion of of terminal phalanx and loss of terminal phalanx and loss of oppositionopposition

• Wasting Wasting of thenar eminenceof thenar eminence• Hand looks flattened and Hand looks flattened and

“apelike”, “apelike”, and presents an and presents an inability to flex the three most inability to flex the three most radial digits when asked to make a radial digits when asked to make a fist. fist.

Wasting of thenar eminence

Ulnar deviation

• Sensory Effects: Loss of sensation from:The radial side of the palmPalmer aspect of the

lateral 3½ fingersDistal part of the dorsal

surface of the lateral 3½ fingers

• Trophic Changes:Dry and scaly skinEasily cracking nailsAtrophy of the pulp of the

fingers

• Often injured by penetrating wounds (stab wounds or broken glass) of the forearm.

• Motor: Thenar muscles are paralyzed and atrophy in time so that

the thenar eminence becomes flattenedOpposition and abduction of thumb are lost, and thumb

and lateral two fingers are arrested in adduction and hyperextension position. “Apelike hand”

• Sensory & trophic changes are the same as in the elbow region injuries

Median Nerve Lesion at the WristMedian Nerve Lesion at the Wrist

• The commonest neurological problem associated with the median nerve is compression beneath the flexor retinaculum at the wrist

• Motor: Weak motor function of thumb, index & middle finger

• Sensory: Burning pain or ‘pins and needles’ along the distribution of median nerve to lateral 3½ fingers

Carpal Tunnel SyndromeCarpal Tunnel Syndrome

No sensory changes over the palm as the palmer cutaneous branch is given before the median nerve enters

the carpal tunnel

Summary• Axillary NerveAxillary Nerve• Origin:

Posterior cord• Spinal

segments: C5, C6

• Function: • Motor:

Deltoid, teres minor

• Sensory: Skin over upper lateral part of arm

Median Nerve• Origin: Medial and lateral cords• Spinal segments: (C5), C6 to T1• Function:

MotorAll muscles in the anterior compartment of the forearm (except flexor carpi ulnaris and medial half of flexor digitorum profundus), three thenar muscles of the thumb and two lateral lumbrical muscles

SensorySkin over the palmar surface of the lateral three and one-half digits and over the lateral side of the palm and middle of the wrist