Infraspinatus muscle

The Infraspinatus muscle (pronounced as in-fruh-spy-nuh-tuhs muhs-uhl) is a thick triangular muscle, which occupies the chief part of the infraspinatous fossa. It is one of the four muscles of the rotator cuff, and is involved in the lateral rotation of the humerus.

Etymology

The term "Infraspinatus" is derived from the Latin words 'infra', meaning 'below', and 'spina', meaning 'spine'. This refers to the muscle's location - below the spine of the scapula.

Anatomy

The Infraspinatus muscle originates from the medial three quarters of the infraspinatous fossa, and converges to a tendon that attaches at the middle facet of the greater tubercle of the humerus. The muscle is innervated by the suprascapular nerve.

Function

The primary function of the Infraspinatus muscle is to laterally rotate the arm at the shoulder joint. It also helps in the stabilization of the shoulder joint during movements.

Related Terms

Rotator cuff: A group of muscles and tendons that surround the shoulder joint, providing stability and allowing a wide range of movements.
Humerus: The long bone in the upper arm located between the shoulder joint and the elbow.
Scapula: Also known as the shoulder blade, it connects the humerus bone of the arm to the collarbone.
Suprascapular nerve: A nerve that passes beneath the scapula, supplying the supraspinatus and infraspinatus muscles.