Supraspinatus muscle

The supraspinatus muscle is found in the supraspinatus fossa of the scapula, and one of the four muscles that forms the rotator cuff. The muscle attaches to the medial two thirds of the floor of the fossa directly on the bone and on the deep aspect of the supraspinatus fascia which covers the muscle. The supraspinatus fascia and the supraspinatus fossa form an osteofascial case for the origin of this muscle.

The fibers of the muscle converge and pass deep to the acromion, forming an osseous tunnel that could entrap the muscle and tendon causing a supraspinous impingement syndrome. The side image in this article has the acromion cut off to show the muscle better. The animated image at the bottom of the article shows the supraspinatus muscle and its relation to the acromion process.

The supraspinatus tendon attaches to the capsule of the glenohumeral joint at the level of the highest of the three impressions that form the greater tubercle of the humerus.

Supraspinatus muscle - Image modified from the original by Henry VanDyke Carter, MD. Public domain
Supraspinatus muscle.
Click on the image for a larger depiction 
It receives innervation by way of the suprascapular nerve (C5, C6), which arises from the superior trunk of the brachial plexus.

The main function of the supraspinatus muscle is to abduct the arm. As part of the shoulder’s rotator cuff it helps prevent subluxation of the glenohumeral joint by keeping the head of the humerus in situ.

The supraspinatus is one of the 17 muscles that attach to the scapula.

Note: The side image modified from the original by Henry VanDyke Carter, MD. Public domain. Animated image below by Wikimedia Commons - Anatomography [CC BY-SA 2.1 jp (https://creativecommons.org/licenses/by-sa/2.1/jp/deed.en)]

Anatomography [CC BY-SA 2.1 jp (https://creativecommons.org/licenses/by-sa/2.1/jp/deed.en)]

Sources:
1. “Gray’s Anatomy” Henry Gray, 1918
2. "Tratado de Anatomia Humana" Testut et Latarjet 8th Ed. 1931 Salvat Editores, Spain
3. "Gray's Anatomy" 38th British Ed. Churchill Livingstone 1995

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