Teres minor muscle

The Teres minor is a narrow, elongated muscle of the rotator cuff.

Origin and insertion
It arises from the dorsal surface of the axillary border of the scapula for the upper two-thirds of its extent, and from two aponeurotic laminæ, one of which separates it from the Infraspinatus, the other from the Teres major.

Its fibers run obliquely upward and lateralward; the upper ones end in a tendon which is inserted into the lowest of the three impressions on the greater tubercle of the humerus; the lowest fibers are inserted directly into the humerus immediately below this impression.

Relations
The tendon of this muscle passes across, and is united with, the posterior part of the capsule of the shoulder-joint.

Action
The Infraspinatus and Teres minor rotate the head of the humerus outward; they also assist in carrying the arm backward.

Variations
Sometimes a group of muscle fibres from teres minor may be fused with Infraspinatus.