The subscapularis muscle is a muscle of the shoulder that connects the scapula (shoulder blade) to the humerus. When contracted, it medially rotates the arm and stabilizes the shoulder joint.
The subscapularis muscle originates from the scapula, on the medial two thirds of the subscapular fossa.
The subscapularis muscle inserts on the upper end of the humerus at several points:
- The lesser tubercle,
- the upper medial lip of the bicipital groove, and
- the humeral capsule.
The subscapularis muscle is innervated by the upper and lower subscapular nerves (C5, C6).