Median nerve

Median nerve
Dr Prashant Shringi
Senior Resident
Neurology

• Lateral cord is made up of C6–C7 fibers and supplies median
sensory fibers to the thenar eminence, thumb, index, and
middle fingers, and motor fibers to the proximal median
forearm muscles
• Medial cord, composed of C8–T1 fibers, supplies motor fibers
to the median muscles of the distal forearm and hand, as well
as sensory fibers to the lateral half of the ring finger

MEDIAN NERVE C6 ,C7& C8,T1
• Origin:
• By 2 roots from the medial and lateral cords of brachial
plexus.
• The medial root crosses the 3rd part of axillary artery to join
the lateral root.
• It runs downward on the lateral side of the brachial artery.
• At the elbow, it lies medial to the tendon of biceps & it is
crossed by the bicipital aponeurosis
• It has no branches in the arm.

 In the cubital fossa it lies deep
to the bicipital aponeurosis.
 It leaves the fossa between the
2 heads of the pronator teres.
 Then it descends between the
flexor digitorum superficialis &
the flexor digitorum profundus.
 It passes to the palm deep or
through the carpal tunnel
lateral to the tendon of flexor
digitorum superficialis, and
deep to the tendon of palmaris
longus.

• Muscular: To
• Pronator teres,
• Flexor carpi radialis,
• Palmaris longus,
• Flexor digitorum superficialis.
• Palmar cutaneous branch:
• It arises at the distal part of
forearm.. It descends superficial
to flexor retinaculum to supply
skin of the lateral 2/3 of the
palm.
• Articular: To elbow joint.
• Anterior interosseous
nerve:proximal forearm
• Descends between flexor pollicis
longus and flexor digitorum
profundus, anterior to the
interosseous membrane.
• It supplies : FPL+PQ+ lateral half
of FDP.
• It gives an articular branches to
wrist & distal radioulnar joint.

Median nerve in the palm
•It enters the palm through the carpal tunnel,
deep to the flexor retinaculum.
•Then it divides into lateral & medial
branches.
•Lies a finger breadth distal to the tubercle
of scaphoid.

Branches in palm
• Muscular: To ( 5 Muscles).
• Abductor pollicis brevis.
• Flexor pollicis brevis. Thenar eminence
• Opponens pollicis
• Lateral 2 lumbrical (1st & 2nd ).
• Digital cutaneous branches :
• Cutaneous branches to the palmar aspect of the
lateral 3 ½ fingers

Motor Functions
• Main median nerve
• Pronator teres (C6–C7), a forearm pronator
• Flexor carpi radialis (C6–C7), a radial flexor of the
hand
• Palmaris longus (C7–T1), a flexor of the wrist.
• Flexor digitorum superficialis (C7–T1), a flexor of the
middle phalanges of the second, third, fourth, and
fifth fingers

• motor anterior interosseus nerve
• Flexor pollicis longus (C7–C8), flexor of the terminal
phalanx of the thumb
• Flexor digitorum profundus I and II (C7–C8), flexor of
the terminal phalanges of the second and third
fingers
• Pronator quadratus (C7–C8), a forearm pronator

Small muscles of hand
• Abductor pollicis brevis (C8–T1), abductor of the metacarpal
of the thumb
• Opponens pollicis (C8–T1), muscle that brings the metacarpal
of the thumb into opposition
• Superficial head of the flexor pollicis brevis (C8–T1), a flexor
of the proximal phalanx of the thumb
• Lumbricals I and II (C8–T1), flexors of the MCP proximal IP and
extensors of the two distal phalanges of the second and third
fingers

Localisation of lesion
• Lesions in the Axilla and Upper Arm:
• Median neuropathies in the axilla are often associated with
damage to the ulnar and radial nerves (triad neuropathy)
 paralysis of all the muscles innervated by the median nerve
 sensory loss in the distribution of both the palmar cutaneous
and palmar digital branches.
 Atrophy of the thenar eminence, affecting especially the
abductor pollicis brevis and the opponens pollicis
• simian hand or ape hand
• benediction hand

Complete high median neuropathy

Pronator Syndrome
• Pain may be present in the proximal forearm, especially on
resistance to pronation of the forearm and flexion at the wrist
• Tenderness is observed over the pronator teres muscle
• Atrophy and paresis of the median thenar musculature occur
• Paresthesias and sensory loss are observed in the median
field of innervation

ANTERIOR INTEROSSEOUS
NERVE SYNDROME
• largest branch of the median nerve, leaves the main trunk of
the median nerve just distal to the PT to innervate three
muscles: FPL, FDP to digits 2 and 3, and PQ.
• No cutaneous sensory fibers, purely motor syndrome
 Pain is present in the proximal forearm or arm
 Mild paresis of forearm pronation (due to pronator quadratus
weakness)
 Paresis of flexion of the terminal phalanges of the second and
third fingers (due to paresis of the flexor digitorum profundus
I and II)
 Paresis of flexion of the terminal phalanx of the thumb (due to
paresis of the flexor pollicis longus)

• Lesions of the Palmar Cutaneous Branchof
the Median Nerve: arises 5 cm above carpel
tunnel
• Lesions within the Hand

ELECTROPHYSIOLOGIC
EVALUATION
 Demonstrating focal slowing or conduction block of median
nerve fibers across the carpal tunnel
 Excluding median neuropathy in the region of the elbow
 Excluding brachial plexopathy predominantly affecting the
median nerve fibers
 Excluding cervical radiculopathy, especially C6 and C7
 If a coexistent polyneuropathy is present, ensuring thatnany
median slowing at the wrist is out of proportion tonslowing
expected from the polyneuropathy alone

Nerve Conduction Studies in proximal
median neuropathy

Median nerve

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