List of external rotators of the human body

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The external rotators of the human body are muscles that facilitate the outward rotation of limbs, particularly the shoulder and hip joints. These muscles are crucial for various movements and stability of the joints.

External Rotators of the Shoulder

The shoulder joint, or glenohumeral joint, is capable of a wide range of motion, including external rotation. The primary muscles responsible for this movement include:

• Infraspinatus muscle: This muscle is part of the rotator cuff and is located on the back of the shoulder. It is a major external rotator of the shoulder.
• Teres minor muscle: Also part of the rotator cuff, this muscle assists the infraspinatus in rotating the arm outward.
• Deltoid muscle (posterior fibers): The posterior fibers of the deltoid muscle contribute to external rotation of the arm.

External Rotators of the Hip

The hip joint, or acetabulofemoral joint, also allows for external rotation. The muscles involved in this movement include:

• Piriformis muscle: This muscle is located in the buttock region and is one of the lateral rotators of the hip.
• Obturator internus muscle: This muscle helps rotate the thigh laterally and stabilizes the hip joint.
• Gemellus superior muscle: Works with the obturator internus to rotate the thigh externally.
• Gemellus inferior muscle: Assists in external rotation of the hip.
• Quadratus femoris muscle: A strong external rotator of the thigh.
• Obturator externus muscle: This muscle also contributes to the lateral rotation of the thigh.

Function

External rotators play a vital role in the stability and movement of the shoulder and hip joints. They are essential for activities that involve throwing, swinging, and other actions requiring outward rotation of the limbs.

Clinical Significance

Weakness or injury to the external rotators can lead to joint instability and impaired movement. Conditions such as rotator cuff tears or piriformis syndrome can affect these muscles, leading to pain and dysfunction.

See Also

• Internal rotators of the human body
• Muscle
• Joint

References

• Gray's Anatomy
• Netter's Atlas of Human Anatomy