Subscapularis Muscle: Definition, Function & Innervation

Instructor: Dan Washmuth

Dan has taught college Nutrition, Anatomy, Physiology, and Sports Nutrition courses and has a master's degree in Dietetics & Nutrition.

Do you know much about the definition, innervation, and function of the subscapularis, a muscle located in each side of the upper back? If not, then be sure to check out this lesson for lots of interesting facts about this muscle!

Subscapularis

Is your subscapularis muscle functioning correctly? If you are like the vast majority of people, you probably have no idea. No need to worry though, you can easily find out if your subscapularis muscle is functioning correctly by following these simple steps:

  1. Stand up with your arms hanging naturally at their sides
  2. Cross your arms in front of your chest, then uncross them
  3. Now raise your arms to your front then pull the arms down back to your sides

If you were able to do those three steps, then it seems as though your subscapularis muscle is functioning just as it should!

Subscapularis: Definition

The subscapularis is a large, triangular-shaped muscle located in each side the upper back, making up part of the shoulder joint. The name of this muscle gives away its exact location in the body. The prefix sub means 'under' or 'beneath', while scapularis refers the the 'scapula', which is the official name of the shoulder blade. Therefore, the subscapularis muscle is located 'under the scapula'.

The subscapularis muscle is located under the scapula and forms part of the shoulder joint.
shoulder joint

The scapula or shoulder blade contains the subscapular fossa, which is the triangular-shaped concave surface of the inner part of this bone. The subscapularis muscle fills this concave area of the scapula (which explains this muscle's triangular shape).


The subscapularis muscle is located in the subscapular fossa of the shoulder blade, which is highlighted in green in this picture.
subscapular fossa


Have you ever heard of the rotator cuff? The rotator cuff is a collection of four muscles that help keep the bones in the shoulder joint in their proper positions. You may have heard about professional athletes, especially pitchers and quarterbacks (or any other athlete who frequently throws something using the overhand motion), tearing their rotator cuff muscles. The subscapularis is one of these rotator cuff muscles.

Subscapularis: Innervation

Each muscle of the body receives electrical impulses from the brain through a specific nerve or group of nerves (this process is called innervation). The subscapularis muscle is innervated by the upper and lower subscapular nerves, which consists of nerve fibers from several cervical (neck) nerves, including C5, C6, and C7.

Subscapularis: Function

The main function of the subscapularis is to move the humerus, which is the long bone that makes up the upper arm. The following chart describes the specific movements of the humerus caused by this muscle.

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