Subscapularis – last of the rotator cuff muscles
The subscapularis is the last of the four muscles that make up the rotator cuff group, and it is the most powerful of the four. We have already covered the other three muscles in this group, the supraspinatus, infraspinatus, and the teres minor in previous posts.
You can read more about how subscapularis works with other muscles in the rotator cuff muscle group on pages 209-211 (1st ed.) of my book Functional Anatomy of Yoga.
What does subscapularis mean?
The name of this muscle describes its location. Specifically, “sub” means under, and “scapular” means spade, which refers to the shape of the scapula. When we put them together, the muscle names describe the location of this muscle: on the underside of the scapula.
Where does subscapularis attach?
- The muscle itself originates on the subscapular fossa of the scapula (shoulder blade).
- Its insertion or humeral attachment is on the lesser (smaller) tuberosity (bump) on the front of the humerus.
What actions does subscapularis do?
Subscapularis internally rotates the humerus.
What are the most common injuries to subscapularis?
Subscapularis is less likely to be injured than the other rotator cuff muscles. A subscapularis tear is most likely to occur due to a traumatic event such as a fall, an accident. But, it can also occur when a rapid, strenuous movement is done without warming up, or when there is weakness in the muscle after surgery.
- Pain at the front of the shoulder
- Feeling of weakness in the shoulder when twisting the arm inwards or lifting the arm across the front of the body
What to do?
Like tears of the other rotator cuff muscles, subscapularis tears can range from a minor strain requiring rest and possibly physical therapy exercises, to a major tear requiring surgery. If you are concerned about a tear in any of the rotator cuff muscles, consult a medical professional for diagnosis and appropriate treatment.
Postures where this muscle contracts
Hands in reverse prayer require internal rotation at the shoulder joints, which is a function of this muscle.
Postures where this muscle is lengthened
While externally rotating the arms in eagle pose (garundasana) you would lengthen this muscle.
Trigger points are fairly common amongst all of the rotator cuff muscles for yoga practitioners. See the image below for the trigger point referral patterns common to subscapularis. And, if you’d like to learn more, you can read about what trigger points are: here.