Posterior Perspective of the Upper Arm Muscles

Description

Posterior shoulder and brachium anatomy is presented with the deltoid forming the lateral contour over the glenohumeral joint and the scapular spine dividing supraspinatus superiorly from infraspinatus inferiorly. Inferolateral to the scapula, teres minor and teres major frame the posterior axillary fold, while the long head of triceps brachii descends between them from the infraglenoid tubercle. Across the posterior humerus, the lateral and medial heads of triceps occupy the extensor compartment, converging distally into a broad tendon inserting on the olecranon, with the posterior humeral shaft serving as the deep bony reference. Elbow extension dominates this field. The posterior perspective clarifies how the long head of triceps crosses both shoulder and elbow, a point that explains weakness in overhead extension after proximal tendon injury and why shoulder position can change triceps strength testing. Clinically, this orientation also maps the relationship of triceps to the radial nerve in the spiral (radial) groove of the humerus, a frequent site of neuropraxia in midshaft humeral fractures and a key consideration in posterior or posterolateral surgical approaches and during deep intramuscular injection placement. Orthopedic and sports medicine texts use this view to teach triceps tendon anatomy, olecranon insertion, and the functional distinction between the long head and the humeral heads during resisted extension. It also supports surface anatomy instruction for gross anatomy, kinesiology, and strength and conditioning courses where palpation targets include the posterior deltoid, teres major, and the triceps tendon just proximal to the olecranon. Anatomical accuracy verified by SciePro's Medical Advisory Board.