Posterior Brachial Cutaneous Nerve, Posterior View

Description

Running in the posterior compartment of the arm, the posterior brachial cutaneous nerve is traced from its origin in the axillary region as a branch of the radial nerve, then along the deep surface of the triceps brachii, most closely related to the long and lateral heads. Proximally it sits inferior to the posterior aspect of the deltoid and posterior to the humerus, while distally it becomes more superficial as it approaches the posterior mid arm to supply the skin over the posterior arm. Surrounding landmarks typically include the scapula with the posterior rotator cuff (infraspinatus and teres minor), the proximal humerus, and the long head of the biceps brachii anteriorly, kept in context for orientation. Clear boundaries. Clinically, this nerve is a frequent “missing piece” when teaching the radial nerve in the spiral (radial) groove and in the triangular interval, where the radial nerve and profunda brachii artery pass posterior to the humerus between the long head of triceps and the humeral shaft. Iatrogenic injury can occur during a posterior approach to the humerus, open reduction and internal fixation of humeral shaft fractures, or deep intramuscular injections placed too posterior and proximal, producing a patch of hypoesthesia over the posterior arm rather than the classic dorsal hand distribution. That sensory pattern matters when sorting a true radial neuropathy from a more distal posterior interosseous lesion, which spares cutaneous territory. Use this artwork in upper limb anatomy teaching, peripheral nerve block and regional anesthesia guides, or orthopaedic and trauma publications describing posterior humeral exposure and safe dissection planes around triceps. It also supports patient education materials for postoperative sensory changes after humeral shaft fixation or axillary dissection. Anatomical accuracy verified by SciePro's Medical Advisory Board.