Nerve Branch to the Medial Head of the Triceps and Anconeus, Posterior View

Description

Seen from the posterior aspect of a male upper limb, a discrete radial nerve branch courses in the posterior compartment toward the medial head of triceps brachii and continues distally toward anconeus near the posterolateral elbow. The branch tracks along the posterior surface of the humerus, in the region of the radial (spiral) groove, lying deep to the triceps mass and lateral to the long head as it descends. Proximally, the scapula and proximal humerus frame the shoulder region, with the deltoid forming a superficial cap over the posterolateral glenohumeral area while deeper neurovascular elements emerge from the brachial plexus into the arm. Posterior compartment motor branches of the radial nerve matter because their anatomy explains selective patterns of weakness after humeral shaft trauma and during posterior approaches to the arm. A fracture through the mid-diaphysis can injure the radial nerve in the groove, and sparing or involvement of the medial head of triceps helps localize the lesion relative to proximal branches. Anconeus innervation also enters the differential in posterolateral elbow pain and in iatrogenic injury risk during triceps-sparing or triceps-splitting exposure, where the nerve branch can be encountered as it runs toward the anconeus and capsule. Small branch, big consequences. Use this artwork in gross anatomy teaching of the posterior arm, in orthopaedic and trauma publications discussing radial nerve palsy after humeral shaft fracture, or in surgical education materials for posterior humeral and elbow approaches where preservation of motor branches is a practical goal. It also supports radiology correlation when explaining why deficits may not match a single myotome after nerve injury at different arm levels. Anatomical accuracy verified by SciePro's Medical Advisory Board.