Teres Minor Under the Skin

Description

Positioned on the posterior aspect of the left scapula, the teres minor lies along the lateral border, inferior to the infraspinatus and superior to the teres major, with its muscle belly running laterally toward the proximal humerus. The scapular spine and infraspinous fossa provide the bony context, while the head of the humerus sits lateral to the glenoid, partially visible beneath the overlying skin. Posterior thoracic vertebrae and ribs form a medial and anterior backdrop, helping orient the shoulder girdle to the thoracic cage. Spatial relationships are clear. Teres minor is the smallest rotator cuff muscle, but it carries diagnostic weight because it is innervated by the axillary nerve (C5–C6) and can be selectively weak in quadrilateral space syndrome when the posterior circumflex humeral artery and axillary nerve are compressed between teres minor and teres major. External rotation strength testing at 90 degrees of abduction, and the pattern of fatty atrophy seen on MRI in axillary neuropathy, often hinges on knowing where teres minor sits relative to the infraspinatus and humeral head. Surgeons also use this anatomy when working around the posterior shoulder, where the interval between infraspinatus and teres minor is a practical landmark during posterior approaches to the glenohumeral joint. Use this lateral, under-skin male torso view for teaching rotator cuff topography in gross anatomy and kinesiology labs, for orthopaedics and sports medicine texts discussing axillary nerve injury patterns, and for patient-facing materials explaining posterior shoulder pain sources around the quadrilateral space. Anatomical accuracy verified by SciePro's Medical Advisory Board.