Infraspinatus muscle
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| Infraspinatus muscle | ||
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| 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 |
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| Latin | musculus infraspinatus | |
| Gray's | subject #123 441 | |
| Origin: | infraspinous fossa of the scapula | |
| Insertion: | middle facet of greater tubercle of the humerus | |
| Artery: | suprascapular and circumflex scapular arteries | |
| Nerve: | suprascapular nerve | |
| Action: | Lateral rotation of arm & Adduction of arm | |
| Dorlands/Elsevier | m_22/12549360 | |
The Infraspinatus muscle is a thick triangular muscle, which occupies the chief part of the infraspinatous fossa.
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[edit] 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 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.
[edit] 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.
[edit] Action
It is a lateral 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.
[edit] See also
[edit] Additional images
 Left scapula. Dorsal surface. |
 Left humerus. Posterior view. |
 Muscles connecting the upper extremity to the vertebral column. |
 The scapular and circumflex arteries. |
 Suprascapular and axillary nerves of right side, seen from behind. |
 The suprascapular, axillary, and radial nerves. |
[edit] External links
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
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