Deltoid Region of the Upper Limbs, Posterior View

Description

Posterior surface anatomy of the shoulder girdle is emphasized, with the highlighted field corresponding to the deltoid region overlying the acromion and lateral scapular spine, wrapping from the posterolateral clavicle and acromion toward the deltoid tuberosity of the humerus. Laterally, the deltoid contour frames the rounded shoulder, while medially it borders the scapular spine and the posterior margin of the trapezius. Inferiorly, the deltoid blends toward the posterior axillary fold, where the teres major and latissimus dorsi contribute to the fold deep to the superficial silhouette. Arms rest in slight external rotation, so the posterior deltoid sweep and the line of the triceps brachii long head sit in clear relation to the glenohumeral articulation. Posterior deltoid topography matters whenever you need reliable surface landmarks for injection safety, nerve injury patterns, or operative portals. The axillary nerve courses deep to the deltoid after passing through the quadrangular space (bounded by teres minor superiorly, teres major inferiorly, long head of triceps medially, and surgical neck of humerus laterally), so trauma at the surgical neck or anterior shoulder dislocation can present with deltoid flattening and sensory loss over the superior lateral arm. This is a high-yield map. Use this asset in gross anatomy and surface anatomy teaching to link scapular bony landmarks to the deltoid’s posterior fibers, or in clinical skills materials covering intramuscular deltoid injections and landmarking away from the acromion and axillary nerve. It also suits orthopedic and sports medicine publications discussing posterior shoulder pain patterns, rotator cuff pathology referral, and postoperative approaches around the deltoid splitting interval. Anatomical accuracy verified by SciePro's Medical Advisory Board.