infraspinatus

Intrinsic muscle of the shoulder (scapulohumeral). One of its tendons contributes to formation of the "rotator cuff". Origin: infraspinous fossa of the scapula Insertion: -> middle facet of the greater tubercle of humerus Action: 1) extends arm 2) rotates arm laterally 3) tonic contraction helps to hold the head of the humerus in the shallow glenoid fossa Innervation: -> suprascapular nerve (C5, C6)

References

Stedman's Medical Dictionary 27th ed, Williams & Wilkins, Baltimore, 1999