The infraspinatus muscle is situated in the posterior aspect of the scapula, forming part of the rotator cuff in the shoulder. It is a triangular muscle that occupies the infraspinous fossa.
Originating from the infraspinous fossa of the scapula, the infraspinatus takes its starting point from the bony surface on the posterior aspect of the shoulder blade.
The muscle inserts into the greater tubercle of the humerus, specifically on the posterior facet. This insertion site establishes a connection with the upper part of the arm bone.
Functionally, the infraspinatus is a crucial external rotator of the shoulder joint. It plays a key role in turning the humerus outward, contributing to the overall range of motion in the shoulder. Additionally, the muscle aids in stabilizing the shoulder joint during arm movements, providing dynamic stability and preventing dislocation. The infraspinatus is actively engaged in actions such as throwing, reaching, and lifting, showcasing its significance in shoulder biomechanics and overall upper limb function.