The infraspinatus muscle is a thick triangular shaped muscle which arises from the infraspinous fossa below the spine of the scapula. It forms a tendon which inserts on the middle facet of the greater tubercle of the humerus.
Origin
- Infraspinous fossa on the dorsal surface of scapula (below the spine of the scapula)
Insertion
- Greater tubercle of humerus (middle facet)
Action
- Lateral rotation of the humerus
- Assists in stabilisation of the glenohumeral joint
Innervation
- Suprascapular nerve: C5, 6
Blood Supply
- Suprascapular nerve: C4, 5, 6
Antagonist
- Suprascapular and circumflex scapular arteries