Infraspinatus muscle
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{{Muscle infobox |
Name = {{PAGENAME}} |
Latin = musculus infraspinatus |
GraySubject = 123 |
GrayPage = 441 |
Image = Arm muscles back numbers.png |
Caption = Muscles on the dorsum of the [[scapula]], and the [[Triceps brachii muscle]]: #3 is [[Latissimus dorsi muscle]]<BR>#5 is [[Teres major muscle]]<BR>#6 is [[Teres minor muscle]]<BR>#7 is [[Supraspinatus muscle]]<BR>#8 is [[Infraspinatus muscle]]<BR>#13 is long head of [[Triceps brachii muscle ]] |
Image2 = Infraspinatus.PNG |
Caption2 = Muscles connecting the upper extremity to the [[vertebral column]]. |
Origin = [[infraspinous fossa]] of the [[scapula]] |
Insertion = middle facet of [[greater tubercle]] of the [[humerus]] |
Blood = [[suprascapular]] and [[circumflex scapular]] arteries |
Nerve = [[suprascapular nerve]] |
Action = [[Lateral rotation]] of arm & [[Abduction]] of arm and stabilizes [[humerus]]|
MeshName = |
MeshNumber = |
DorlandsPre = m_22 |
DorlandsSuf = 12549360 |
}}
The '''Infraspinatus muscle''' is a thick triangular [[muscle]], which occupies the chief part of the [[infraspinatous fossa]].
==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]].
==Relations==
The tendon of this muscle is sometimes separated from the capsule of the [[shoulder-joint]] by a [[Bursa (anatomy)|bursa]], which may communicate with the joint cavity.
==Action==
It is a lateral rotator of the [[glenohumeral]] joint and [[abductor]] 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.{{Fact|date=October 2007}}
==See also==
* [[Rotator cuff]]
==External links==
* {{MuscleLoyola|infs}}
* {{SUNYAnatomyFigs|03|03|04}}
* {{eMedicineDictionary|infraspinatus+muscle}}
{{Gray's}}
{{Muscles of upper limb}}
{{muscle-stub}}
[[Category:Muscles of the upper limb]]
[[ar:عضلة تحت الشوكة]]
[[cs:Podhřebenový sval]]
[[de:Musculus infraspinatus]]
[[fr:Muscle infra-épineux]]
[[hr:Podgrebeni mišić]]
[[id:Otot infraspinatus]]
[[he:השריר המך קוצי]]
[[la:Musculus infraspinatus]]
[[hu:Tövis alatti izom]]
[[nl:Musculus infraspinatus]]
[[pl:Mięsień podgrzebieniowy]]
[[pt:Músculo infra-espinhal]]
[[sv:Infraspinatus]]
[[sl:Podgrebenčnica]]