Infraspinatus muscle
Musculus infraspinatus
Definition
Infraspinatus muscle | |||
Origin | Infraspinous fossa of the scapula | ||
Insertion | Middle facet of the greater tubercle of the humerus | ||
Artery | Suprascapular and circumflex scapular arteries | ||
Innervation | Suprascapular nerve (C5, C6) | ||
Action | Lateral rotation of the arm, stabilizes the humerus | ||
Antagonist | Subscapularis, pectoralis major, and latissimus dorsi | ||
Origin
The infraspinatus muscle is a thick, triangular muscle from the infraspinous fossa of the scapula, occupying much of its posterior aspect. It is one of the four rotator cuff muscles. Covered by the infraspinatous fascia, the muscle is anatomically distinct from adjacent muscles like the teres minor and teres major.
Insertion
Its distal tendinous portion runs laterally and crosses the shoulder joint from behind. It blends with the joint capsule before inserting onto the middle facet of the greater tubercle of the humerus, between the attachments of the supraspinatus (superiorly) and teres minor (inferiorly).
References
Mulla DM, Hodder JN, Maly MR, Lyons JL, Keir PJ. Glenohumeral stabilizing roles of the scapulohumeral muscles: Implications of muscle geometry. J Biomech. 2020 Feb 13;100:109589.
Jones, O. (2024) ‘The Intrinsic Muscles of the Shoulder’, TeachMeAnatomy. Last updated: September 28, 2024. Available at: https://teachmeanatomy.info/upper-limb/muscles/shoulder/intrinsic/
