Anatomy, Shoulder and Upper Limb, Median Nerve

The nerves supplying the upper limb originate from the brachial plexus, which is formed by the anterior rami of spinal nerves C5 to T1. The roots combine to form the superior (C5-C6), middle (C7), and inferior (C8-T1) trunks. Each trunk divides into anterior and posterior divisions that reorganize into the lateral, medial, and posterior cords. The median nerve, 1 of the 5 terminal branches of the brachial plexus, is formed by the union of the lateral and medial cords. The combined fibers from C5 to T1 contribute to the entire cervical enlargement, resulting in a mixed nerve with a broad segmental origin. The median nerve innervates most forearm flexors and several intrinsic hand muscles. Knowledge of median nerve anatomy and physiology is essential for diagnosing neuropathies such as carpal tunnel syndrome (CTS), localizing lesions after trauma, and interpreting electrodiagnostic studies. Surgical planning for nerve repair, tendon transfers, or decompression procedures relies on the precise understanding of the nerve's course, branches, and motor distribution. Awareness of anatomic variations prevents iatrogenic injury during procedures involving the axilla, arm, or wrist and guides rehabilitation strategies that restore function and preserve fine motor control.