Corpus: Teres minor muscle

The teres minor muscle originates from the lateral border (Margo lateralis) of the scapula. Its fibers run cranially and laterally, radiating into the capsule of the shoulder joint.

The insertion of the muscle is at the greater tubercle of the humerus.

The lateral part of the teres minor muscle is covered by the deltoid muscle, and the medial part is covered by the infraspinatus muscle, with which it shares a common fascia, the infraspinatus fascia. Its muscle belly, together with the teres major muscle, forms the cranial boundary of the two axillary spaces through which the vascular and nerve pathways of the shoulder run.

The innervation of the teres minor muscle is provided by the axillary nerve from the brachial plexus (segments: C5-C6, occasionally with parts from C4).

The teres minor muscle supports the external rotation, retroversion, and adduction of the upper arm. As part of the rotator cuff, it serves to stabilize the shoulder joint. Due to its fiber direction, it slightly pulls the head of the humerus (Caput humeri) downward during contraction, thus relieving the soft tissues beneath the shoulder roof.