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Infraspinatus

The infraspinatus (Latin: musculus infraspinatus) is a flat, triangular shaped muscle of the shoulder girdle, belonging to the rotator cuff muscles.

Origin

The infraspinatus muscle originates from the walls of the infraspinous fossa on the posterior surface of the scapula.

Insertion

The infraspinatus fills the infraspinous fossa of the scapula. The muscle fibers of the infraspinatus travel laterally and insert onto the greater tubercle of the humerus.

Action

The infraspinatus stabilizes the glenohumeral joint and provides external rotation of the upper arm.

Innervation

The infraspinatus is innervated by the suprascapular nerve (C5 - C6).

Blood supply

The blood supply to the infraspinatus muscle is largely provided by the supraspinatus artery and the circumflex scapular artery