Which rotator cuff muscle produces internal rotation of the shoulder?

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The rotator cuff is a group of four muscles and their associated tendons located in the shoulder. These muscles play a crucial role in stabilizing and enabling various movements of the shoulder joint. One of the key functions of the rotator cuff muscles is facilitating internal and external rotation of the shoulder. In this article, we will focus on the specific muscle responsible for internal rotation.

The Rotator Cuff Muscles

Before delving into the muscle responsible for internal rotation, let’s briefly introduce the four rotator cuff muscles:

  1. Supraspinatus: This muscle initiates abduction (lifting the arm away from the body) of the shoulder.
  2. Infraspinatus: It primarily handles external rotation, but also assists in stabilizing the shoulder joint.
  3. Teres Minor: Like the infraspinatus, the teres minor aids in external rotation and helps stabilize the shoulder.
  4. Subscapularis: This muscle is the key player in internal rotation of the shoulder.

The Subscapularis Muscle: Internal Rotation Powerhouse

Anatomy and Location

The subscapularis muscle is located on the anterior surface of the scapula (shoulder blade). It originates from the subscapular fossa, a concave depression on the anterior surface of the scapula, and inserts onto the lesser tubercle of the humerus.

Function: Internal Rotation of the Shoulder

The primary function of the subscapularis muscle is to internally rotate the shoulder joint. When the subscapularis contracts, it causes the arm to rotate inward towards the body. This motion is commonly used in activities such as reaching behind the back or fastening a seatbelt.

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Clinical Significance

  1. Rotator Cuff Tears: Injuries to the rotator cuff, including the subscapularis, can occur due to trauma, overuse, or degenerative changes. Rotator cuff tears can lead to weakness and limited range of motion in the affected shoulder.
  2. Rehabilitation and Strengthening: Physical therapy and targeted exercises are often prescribed to rehabilitate the rotator cuff, including the subscapularis, after injuries or surgeries.

Conclusion

The subscapularis muscle, one of the four rotator cuff muscles, plays a critical role in internal rotation of the shoulder joint. Understanding the functions and anatomy of these muscles is essential for comprehending the complex mechanics of the shoulder. If you experience any shoulder pain or discomfort, it is advisable to seek medical attention and consult with a healthcare professional for proper diagnosis and treatment. Remember, a healthy and functional shoulder is key to a wide range of daily activities and overall quality of life.

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