The Nerve Supply of the Arm of an Adult Human Male

Description

Beginning proximally at the lower cervical spine, the sequence traces the ventral rami of C5 to T1 as they emerge between the anterior and middle scalene muscles and assemble into the roots, trunks, divisions, and cords of the brachial plexus deep to the clavicle. Branches peel away in order, including the dorsal scapular and long thoracic nerves running posteriorly toward levator scapulae, rhomboids, and serratus anterior, and the suprascapular nerve coursing laterally toward the suprascapular notch. Distal to the axilla, the musculocutaneous, median, ulnar, radial, and axillary nerves are followed along the arm in relation to the axillary and brachial arteries, with the radial nerve spiraling posteriorly in the radial groove and the ulnar nerve tracking medially toward the cubital tunnel behind the medial epicondyle. Landmarks stay clear. Course and branching feel spatial, not schematic. Clinically, mapping these trajectories matters when localizing weakness and sensory loss after traction injury, fracture, or entrapment. A stepwise animation clarifies what a static plate often obscures: how upper trunk lesions (Erb-Duchenne palsy) selectively compromise shoulder abduction and elbow flexion, how posterior cord involvement produces wrist drop via the radial nerve, and why long thoracic nerve palsy yields scapular winging despite an intact glenohumeral joint. Watching the cords reorganize around the second part of the axillary artery also supports safe needle placement for infraclavicular blocks and explains patterns seen in thoracic outlet syndrome. Use it for gross anatomy and neuroanatomy teaching on the upper limb, for board-style lesion localization questions, and for surgical and anesthesia education covering axillary dissection, humeral shaft fractures, and regional anesthesia approaches to the brachial plexus. It also fits patient-facing counseling when explaining postoperative neuropraxia after shoulder arthroscopy or compressive neuropathies at the cubital tunnel and carpal tunnel. Anatomical accuracy verified by SciePro's Medical Advisory Board.