Where does the subscapularis muscle originate?

The subscapularis muscle originates from the subscapular fossa of the scapula, which is located on the anterior surface of the scapula. This positioning allows the muscle to effectively function as an internal rotator of the humerus, as well as contribute to shoulder stability. The subscapularis is part of the rotator cuff group, which includes several muscles that work in concert to support shoulder movement and maintain its integrity.

The other options refer to anatomical structures that are not related to the origin of the subscapularis. The medial clavicle is associated with muscles like the pectoralis major. Meanwhile, the lateral and medial epicondyles of the humerus serve as attachment points for various forearm muscles, but they do not pertain to the subscapularis muscle's origin. Understanding the specific origin of the subscapularis helps in both anatomical knowledge and practical application in sports massage, particularly when addressing shoulder mechanics.