Infraspinatus muscle
| Infraspinatus muscle | |
|---|---|
 Muscles on the dorsum of the scapula, and the Triceps brachii muscle: #3 is Latissimus dorsi muscle #5 is Teres major muscle #6 is Teres minor muscle #7 is Supraspinatus muscle #8 is Infraspinatus muscle #13 is long head of Triceps brachii muscle | |
 Muscles connecting the upper extremity to the vertebral column. | |
| Details | |
| Origin | infraspinous fossa of the scapula |
| Insertion | middle facet of greater tubercle of the humerus |
| Artery | suprascapular and circumflex scapular arteries |
| Nerve | suprascapular nerve |
| Actions | Lateral rotation of arm and stabilizes humerus |
| Identifiers | |
| Latin | musculus infraspinatus |
| TA98 | A04.6.02.008 |
| TA2 | 2458 |
| FMA | 32546 |
| Anatomical terms of muscle | |
The Infraspinatus muscle is a thick triangular muscle, which occupies the chief part of the infraspinatous fossa. The infraspinatus is a muscle of the rotator cuff, and is innervated by the suprascapular nerve.
Origin and insertion
It attaches medially to the infraspinous fossa of the scapula and laterally to the greater tubercle of the humerus.
It arises by fleshy fibers from its medial two-thirds, and by tendinous fibers from the ridges on its surface; it also arises from the infraspinatous fascia which covers it, and separates it from the Teres major and Teres minor.
The fibers converge to a tendon, which glides over the lateral border of the spine of the scapula, and, passing across the posterior part of the capsule of the shoulder-joint, is inserted into the middle impression on the greater tubercle of the humerus.
Relations
The tendon of this muscle is sometimes separated from the capsule of the shoulder-joint by a bursa, which may communicate with the joint cavity.
Action
It is an external rotator of the glenohumeral joint and adductor of the arm.
The Infraspinatus and Teres minor rotate the head of the humerus outward (external rotation); they also assist in carrying the arm backward. Studies by Lastayo, w., etc. have shown the infraspinatus to be the major external rotator of the shoulder in comparison with the teres minor.[citation needed]
See also
External links
- Template:MuscleLoyola
- Anatomy figure: 03:03-04 at Human Anatomy Online, SUNY Downstate Medical Center
- Template:EMedicineDictionary
This article incorporates text in the public domain from page 441 of the 20th edition of Gray's Anatomy (1918)
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