Muscle · Shoulders

Subscapularis

Musculus subscapularis

The only rotator cuff muscle on the front of the shoulder blade — a thick triangular sheet filling the whole surface that faces the ribs, hidden between the blade and the chest wall. It is the shoulder's principal internal rotator, the muscle behind reaching into a back pocket or tucking in a shirt, and the anterior half of the cuff's grip on the head of the arm bone: the front wall that stops the humerus drifting forward while the muscles behind it pull the other way. It is also the hardest cuff muscle to reach, since almost all of it is pressed against the ribcage.