Medial Head of the Triceps, Posterior View

Description

Posteriorly, the caput mediale of the triceps brachii is highlighted along the distal half of the posterior arm, lying deep to the caput longum medially and the caput laterale laterally, and closely applied to the posterior surface of the humeral shaft. Its muscle fibers course inferiorly toward the common triceps tendon, which inserts on the olecranon of the ulna, creating a clear proximal to distal line of action for elbow extension. Superiorly, the posterior deltoid and the scapular region frame the upper arm, while the medial head occupies the deeper plane adjacent to the humerus. Deep. That tight relationship to the humerus matters because the medial head overlies the region of the radial nerve and profunda brachii artery as they traverse the spiral (radial) groove, so posterior arm trauma or humeral shaft fractures can disrupt elbow extension and wrist or finger extension in the same clinical picture. In posterior approaches to the humerus and during triceps-splitting or triceps-reflecting exposures, surgeons use the triceps heads as layered landmarks to protect the nerve and to regain anatomic planes. The medial head also becomes the reliable workhorse in slow, sustained elbow extension, making it a useful reference when teaching motor testing and grading triceps strength. Use this posterior upper arm view in gross anatomy and kinesiology coursework to distinguish the triceps heads by depth and fiber direction, and in orthopedic or trauma publications discussing the radial groove, humeral shaft fractures, and posterior surgical approaches. It also supports patient-facing education on triceps strain, tendon loading at the olecranon, and postoperative rehabilitation after distal humerus fixation. Anatomical accuracy verified by SciePro's Medical Advisory Board.