Medical Definition of Muscle, infraspinatus
Muscle, infraspinatus: A muscle that assists the lifting of the arm while turning the arm outward (external rotation).
The tendon of the infraspinatus muscle is one of four tendons that stabilize the shoulder joint and constitute the rotator cuff. Each of the four tendons that makes up the rotator cuff hooks up to a muscle that moves the shoulder in a specific direction. The four muscles whose tendons form the rotator cuff are:
- The infraspinatus muscle;
- The teres minor muscle, which (like the infraspinatus muscle) helps in the outward turning (external rotation) of the arm;
- The supraspinatus muscle, which is responsible for elevating the arm and moving it away from the body; and
- The subscapularis muscle, which moves the arm by turning it inward (internal rotation).
Damage to the rotator cuff is one of the most common causes of shoulder pain.
The term "infraspinatis" means below (infra) the spine. The infraspinatus muscle originates below the "spine" of the scapula (the wingbone).
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