The subscapularis (Latin: musculus subscapularis) is a large flat, triangular muscle of the shoulder girdle. It is the largest and most powerful of the rotator cuff muscles.
The subscapularis originates from the subscapular fossa on the costal surface of the scapula.
The subscapularis fills the subscapular fossa, passes laterally upwards and inserts to the lesser tubercle of the humerus.
The subscapularis muscle stabilizes the glenohumeral joint and provides adduction and internal rotation of the upper arm.
The subscapularis is innervated by the subscapular nerve (C5 - C6).
The arterial blood supply to the subscapularis muscle is provided mostly by the subscapular, suprascapular and circumflex scapular arteries.