Shoulder

Description

Posterior shoulder contours dominate this rear view of an adult Black male, with the acromial region forming the superior-lateral cap over the proximal humerus. The deltoid mass is emphasized bilaterally in blue, wrapping from the lateral clavicle and acromion toward the deltoid tuberosity while framing the lateral border of the scapula and the posterior axillary fold. Medially, the scapular spine and infraspinous fossa would lie deep to the superficial outline, and the humeral head sits anterior to the posterior deltoid as it articulates with the glenoid. Surface anatomy matters here because the posterior deltoid overlies structures clinicians target and structures they try to avoid. Intramuscular deltoid injections placed too high or too far posterior risk the axillary nerve and posterior circumflex humeral artery as they course around the surgical neck through the quadrangular space, while injections placed too low drift toward the radial nerve territory along the spiral groove. Palpation and landmarking around the acromion also anchor evaluation of acromioclavicular joint sprain, rotator cuff related subacromial pain, and posterior shoulder tightness that can limit internal rotation in overhead athletes. Use this rear perspective when you need clean external landmarks for a gross anatomy lab manual, an OSCE station on shoulder examination, or patient-facing education on where a deltoid injection should and should not go. It also fits orthopaedic and sports medicine publications discussing posterior shoulder approach, deltoid contour changes after axillary nerve palsy, or postoperative swelling patterns after arthroscopy. Anatomical accuracy verified by SciePro's Medical Advisory Board.