Subscapularis muscle: A muscle that moves the arm by turning it inward (internal rotation).
The tendon of the subscapularis muscle is one of four tendons that stabilize the shoulder joint and constitute the rotator cuff. Each of these four tendons hooks up to a muscle that moves the shoulder in a specific direction.
The four muscles whose tendons form the rotator cuff are:
- The subscapularis muscle;
- The supraspinatus muscle, which is responsible for elevating the arm and moving it away from the body;
- The infraspinatus muscle, which assists the lifting of the arm during turning the arm outward (external rotation);
- The teres minor muscle, which also helps in the outward turning (external rotation) of the arm.
Damage to the rotator cuff is one of the most common causes of shoulder pain.
The term "subscapularis" means under (sub) the scapula (the wingbone). The subscapularis muscle originates there, beneath the scapula.