Subscapularis 

Subscapularis is a muscle and tendon that connects the scapula to the front of the head of the humerus. It is the largest of the four rotator cuff muscles.

Movement

The Subscapularis is responsible for the medial rotation of the humerus (Internal Rotation). However it is important in most shoulder movements.

Subscapularis is highlighted, connecting the scapula from to the front of the head of the humerus.