The subscapularis is a large, triangular muscle attached to the anterior surface of the scapula at the front of the shoulder. It is one of the four muscles of the rotator cuff and helps with internal rotation of the shoulder. Related Definitions Infraspinatus Rotator Cuff Rotator Cuff Tear Subscapularis Teres Minor Editor’s Top Picks Rotator Cuff Injuries How Do Rotator Cuff Injuries Occur? Rotator Cuff Injuries: Symptoms Rotator Cuff Injuries: Diagnosis Rotator Cuff Injuries: Initial Treatment Rotator Cuff Tear Surgery