Subscapularis muscle

Hello again, everyone. This is Matt from Kenhub. And in this tutorial, we will discuss the origin, insertion, innervation, and action of the subscapularis muscle. The subscapularis muscle is one of four muscles that make up the rotator cuff—all of them working together to provide the stability and mobility of the most flexible joint in the human body, the shoulder.

The subscapularis arises from the subscapular fossa and inserts on the lesser tubercle of the humerus.

The nerve supply for the subscapularis muscle is conveniently called the subscapular nerve and arises from the posterior cord of the brachial plexus. The subscapular nerve is further divided into the upper and lower subscapular nerves which innervate the subscapularis.

The main function of the rotator cuff is to stabilize and center the humeral head in the joint socket or the glenoid cavity. In addition, the muscles tighten the joint capsule, preventing a pinch during shoulder movements. The subscapularis muscle is very important for the internal rotation of the humerus. And this internal rotation also supports the upper arm during abduction and adduction.