Infraspinatus Anatomy

Infraspinatus Muscle

Origin: Infraspinous fossa of the scapula
Insertion: Middle facet of the greater tubercle of the humerus
Actions: External rotation of arm
Innervation: Suprascapular nerve (C5, C6)
Blood Supply: Suprascapular Artery and circumflex humeral artery from the axillary artery

Primary Actions of the Infraspinatus

1. Internal rotation of the arm at the shoulder

1. External rotation of the shoulder

Agonists:

  • Teres Minor
  • Deltoid (posterior fibers)

Antagonists:

  • Subscapularis
  • Deltoid (anterior fibers)
  • Latissimus Dorsi
  • Pectoralis Major
  • Teres Major

Advertisement




Secondary Actions of the Infraspinatus

1. Assists with depression of the humeral head

  Agonists:

  • Teres Minor
  • Subscapularis