Infraspinatus

Description[edit | edit source]

A thick, triangular muscle; one of the 4 muscles which comprise the Rotator Cuff of the shoulder.

Infraspinatus muscle back2.png

Origin[edit | edit source]

The infraspinatus fossa of scapula, with some fibres arising from the infraspinatous fascia which covers the muscle and separates it from Teres Major and Teres Minor.[1]

Insertion[edit | edit source]

The posterior aspect of greater tuberosity of humerus, and the capsule of shoulder joint.[2]

Nerve Supply[edit | edit source]

Suprascapular Nerve (C5 & C6)[3]

Blood Supply[edit | edit source]

Suprascapular and circumflex scapular arteries.[3]

Action[edit | edit source]

Infraspinatus is the main external rotator of the shoulder joint.

It assists in producing shoulder extension.

With the arm fixed, it abducts the inferior angle of the scapula. [2]

Function[edit | edit source]

It provides the primary muscle force for external rotation of the shoulder.

Along with the rest of the Rotator Cuff muscles it provides stability to the shoulder complex.[3]

Resources[edit | edit source]

Recent Related Research (from Pubmed)[edit | edit source]

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References
[edit | edit source]

  1. Gray H. Anatomy of the Human Body. Philadelphia: Lea & Febiger, 1918. Available from https://www.bartleby.com/107/123.html (accessed on 29/2/2016)
  2. 2.0 2.1 Wheeles CR. Infraspinatus. Available from: http://www.wheelessonline.com/ortho/infraspinatus (last accessed 29/2/2016)
  3. 3.0 3.1 3.2 AnatomyExpert. 3D Infraspinatus- infraspinatus. Available from: http://www.anatomyexpert.com/app/structure/5510/554/ (last accessed on 29/2/2016)