Deep Branch of the Radial Nerve, Posterior View

Description

Emerging in the posterior aspect of the elbow region, the radial nerve divides near the lateral epicondyle into its superficial branch and the deep branch (motor), which courses anterior to the lateral epicondyle before passing through the supinator to reach the posterior extensor compartment. Along the proximal forearm, the deep branch runs in close relationship to the neck of the radius and the proximal radioulnar joint, then continues distally as the posterior interosseous nerve along the posterior surface of the interosseous membrane between the radius and ulna. Distal to the elbow, the illustration logically includes the superficial radial nerve tracking along the dorsolateral forearm toward the dorsal hand, with the median and ulnar nerves positioned more anteromedially, and the bony framework of the radius, ulna, carpal bones, metacarpals, and phalanges providing clear spatial reference. Articular cartilage is highlighted at the humeroulnar, humeroradial, and wrist joint surfaces. A posterior-oriented pathway view matters because the deep branch of the radial nerve is the structure at risk in posterior interosseous nerve syndrome, commonly from compression within the supinator (arcade of Frohse) or from a proximal radial head or neck fracture. This nerve is motor only once it has entered the supinator, so the pattern of weakness, finger and thumb extension deficits with relative sensory sparing, makes more sense when you can follow its course into the extensor compartment. Small nerve, big functional cost. Use this artwork for upper limb anatomy teaching on forearm compartments and terminal branches of the brachial plexus, and for surgical education around approaches to the radial head, proximal radioulnar joint, and dorsal forearm. It also supports clinical handouts on radial tunnel versus posterior interosseous neuropathy and on iatrogenic risk during lateral elbow procedures. Anatomical accuracy verified by SciePro's Medical Advisory Board.