Muscles Responsible for Forelimb Rotation in Cats & Humans

Subscapularis: This muscle originates from the subscapular fossa of the scapula and inserts onto the lesser tubercle of the humerus. It acts to rotate the forelimb internally.

Teres Major: This muscle originates from the lateral border of the scapula and inserts onto the medial aspect of the humerus. It also acts to rotate the limb inward.