Median Nerve

nervus medianus

The median nerve (C6-T1) is formed from the medial and lateral cords of the brachial plexus, descending through the anterior arm without branching until the elbow where it gives motor branches to the forearm flexors and pronators. It passes through the carpal tunnel to supply the thenar muscles and lateral three and a half fingers. It is the nerve of precision grip and fine digital sensation.

Region: Forearm

Clinical Relevance

Clinical Notes

Carpal tunnel syndrome (median nerve compression under the flexor retinaculum) is the most common peripheral entrapment neuropathy, affecting 3-6% of adults. Symptoms include nocturnal paraesthesia, thenar wasting, and positive Phalen and Tinel signs. Nerve conduction studies confirm the diagnosis. Carpal tunnel release (open or endoscopic) reliably decompresses the nerve. Anterior interosseous nerve syndrome (AIN branch, C8) produces loss of FPL and FDP to index without sensory loss. High median nerve injury (above elbow) produces the pointing index finger on fist closure and loss of pronation.

Pathology

Common Injuries & Conditions

Carpal Tunnel Syndrome

Nocturnal paraesthesia in thumb, index, middle, and radial ring fingers with thenar atrophy in advanced cases — the most common peripheral nerve entrapment.

Pronator Syndrome

Median nerve entrapment at pronator teres producing forearm aching and hand paraesthesia reproduced by resisted pronation with extended elbow.