Axillary & Median NervesAxillary & Median Nerves

Prof. Saeed Makarem

ObjectivesObjectives

At the end of the lecture, you should be able to:• Describe the origin, course, relations, branches

and distribution of the axillaryaxillary & medianmedian nerves.• Describe the common causes and affects of

injury of the axillary and median nerves.

The axillary & median nerves are branches of the The axillary & median nerves are branches of the brachial plexus

The axillary & median nerves are branches of the The axillary & median nerves are branches of the brachial plexus

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

brachial plexus.brachial plexus.Course:Course: • It passes inferiorly and It passes inferiorly and

laterally along the laterally along the posterior wall of the axilla.posterior wall of the axilla.

• Then, it passes posteriorly Then, it passes posteriorly (through a quadrangular (through a quadrangular space) and passes space) and passes around around the surgical neck of the the surgical neck of the humerus. humerus.

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

Axillary NerveAxillary NerveAxillary NerveAxillary Nerve

Branches:Branches:• Motor:Motor: to the to the deltoiddeltoid

and and teres minor teres minor muscles.muscles.

• SensorySensory: : Superior Superior lateral cutaneous lateral cutaneous nerve of arm nerve of arm that that loops around the loops around the posterior margin of the posterior margin of the deltoid muscle to deltoid muscle to innervate skin in that innervate skin in that region. region.

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

surgical neck of the humerus.

2.2. DownwardDownward dislocation of the shoulder joint.

3. Compression. from the incorrect use of crutches.

Axillary Nerve Lesion: CausesAxillary Nerve Lesion: CausesAxillary Nerve Lesion: CausesAxillary Nerve Lesion: Causes11

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Motor: Motor: • Paralysis of the deltoid and Paralysis of the deltoid and

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

shoulder (20-90˚). shoulder (20-90˚). • The paralyzed deltoid wastes The paralyzed 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 compared shoulder is flattened 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: ManifestationsAxillary Nerve Lesion: Manifestations

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

formed lateral to the third part of the axillary artery by the union of:

• Lateral root of median nerve and

• Medial root of median nerve

• Both roots originating from the corresponding 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 of the teres major.teres major.

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

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

• in distal part, itin distal part, it crosses crosses the brachial artery and the brachial artery and descends on its medial descends on its medial side.side.

• Then it passes anterior Then it passes anterior to the elbow jointto the elbow joint. .

Median Nerve in the Arm Median Nerve in the Arm Median Nerve in the Arm Median Nerve in the Arm

The median nerve has The median nerve has NO branches NO branches in in the arm.the arm.

• Median nerve passes into Median nerve passes into the forearm anterior to the forearm anterior to elbow joint, where 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 except: (one and half muscle)

1. F1. Flexor carpi ulnaris,lexor carpi ulnaris, and and 2. M2. Medial half of the flexor edial half of the flexor

digitorum profundus.digitorum profundus.• Both are Both are innervated by innervated by

the the ulnar nerveulnar nerve. .

Median Nerve in the Forearm Median Nerve in the Forearm

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

• It innervates: • Three thenar muscles,

associated with the thumb.

• Lateral 2 lumbrical muscles associated with movement of the index and middle fingers; and

• Skin over the palmar surface of the lateral three and one-half digits and over the lateral 2/3rd of the palm of the hand.

Median Nerve in the HandMedian 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.

• Sites of Median nerve damageSites of Median nerve damage:: At the elbow region: Supracodylar fracture of the At the elbow region: Supracodylar fracture of the

humerus.humerus. At the wrist above the flexor retinaculum.At the wrist above the flexor retinaculum. In the carpal tunnel.In the carpal tunnel.

Median Nerve LesionMedian Nerve LesionMedian 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 possible).like action is not possible).

Loss of sensation Loss of sensation from the from the thumb and lateral 3½ thumb and lateral 3½ fingers & lateral ⅔rd of the fingers & lateral ⅔rd of the palm.palm.

• Damaged in Damaged in supracondylar fracture supracondylar fracture of humerus.of humerus.

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

the forearm.the forearm. All long flexors of All long flexors of

the wrist and fingers the wrist and fingers ExceptExcept flexor carpi flexor carpi ulnaris ulnaris and and medial medial half of flexor half of flexor digitorum digitorum profundus.profundus.

Median Nerve Lesion at the Elbow RegionMedian Nerve Lesion at the Elbow RegionMedian Nerve Lesion at the Elbow RegionMedian Nerve Lesion at the Elbow Region

• Sensory Effects: • Loss of sensation from:

The radial side of the palm.

Palmer aspect of the lateral 3½ fingers.

Distal part of the dorsal surface of the lateral 3½ fingers.

• Trophic Changes:Dry and scaly skin.Easily cracking nails.Atrophy of the pulp of

the fingers.

Motor EffectsMotor Effects: : • Loss of Loss of pronationpronation. . • Hand is kept in supine positionHand is kept in supine position• Wrist shows weak flexion, and Wrist shows weak flexion, and

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

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

• WeakWeak flexion of ring and little flexion of ring and little fingers.fingers.

• Thumb is adducted and laterally Thumb is adducted and laterally rotated, with loss of flexion of rotated, with loss of flexion of terminal phalanx and loss of terminal phalanx and loss of opposition.opposition.

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

““apelikeapelike”, ”, 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

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

• Motor: Thenar muscles are paralyzed and atrophy so the thenar

eminence becomes flattened.Opposition 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 WristMedian 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 fingers.

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

Carpal Tunnel SyndromeCarpal Tunnel SyndromeCarpal Tunnel SyndromeCarpal Tunnel Syndrome

NB. No sensory changes over the palm as the palmer cutaneous branch of the median is given before the median nerve enters the carpal tunnel and this branch passes superficial to the retinaculum).

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, 6,7,8 & 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 lateral 2 lumbrical muscles

SensorySkin over the palmar surface of the lateral three and one-half digits and over the lateral 2/3rd of the palm of the hand.