Muscular branches of median nerve

At a glance

English

Muscular branches of median nerve

Latin (TA2)

Rami musculares nervi mediani

System

Nerve

Region

Upper limb

Side

Paired, left and right

About the muscular branches of median nerve

The median nerve, formed in the axilla from the lateral and medial cords of the brachial plexus, gives no regular branches in the arm. Its muscular branches begin around the elbow and continue into the hand, and they fall into three groups: those from the main trunk in the forearm, those carried by the anterior interosseous nerve, and those in the hand.

Near the elbow the main trunk sends branches to pronator teres, flexor carpi radialis, palmaris longus and flexor digitorum superficialis. As it passes between the two heads of pronator teres it gives off the anterior interosseous nerve. That branch runs down on the interosseous membrane and supplies flexor pollicis longus, the lateral half of flexor digitorum profundus, which serves the index and middle fingers, and pronator quadratus. After passing through the carpal tunnel, the nerve gives a recurrent branch that curls back into the thenar eminence to supply abductor pollicis brevis, opponens pollicis and the superficial head of flexor pollicis brevis. Its digital branches add twigs to the first and second lumbricals.

Damage at different levels gives different signs. A lesion at or above the elbow weakens pronation, wrist flexion and bending of the thumb, index and middle fingers; on trying to make a fist, the index and middle fingers stay straight. Injury to the anterior interosseous nerve alone stops the thumb and index tips from bending, so the patient cannot form a round OK sign. Compression in the carpal tunnel affects only the branches in the hand, leading to wasting of the thenar eminence and weak thumb opposition.

Course and supply

Arises from

Median nerve (C6 to T1) around the elbow and in the forearm, through the anterior interosseous nerve, and in the hand through the recurrent branch and digital nerves.

Ends in

End in the superficial and deep forearm flexors listed, the thenar muscles and the lateral two lumbricals.

Supplies

Motor to pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, flexor pollicis longus, lateral flexor digitorum profundus, pronator quadratus, the thenar muscles and the lateral two lumbricals.