Biomechanics Of Shoulder Joint Quiz

Breathing is not specifically a joint movement because it primarily involves the contraction and relaxation of the diaphragm and intercostal muscles, which are not directly related to joint articulation. Flexion and adduction, on the other hand, are specific joint movements that involve the bending or decreasing of the angle at a joint and the movement of a body part towards the midline of the body, respectively. Therefore, breathing does not fall under the category of joint movements.

Abduction refers to the movement of a body part away from the midline of the body, not towards it. Therefore, the statement "Moving the arm toward the midline of the body is abduction" is incorrect. The correct term for moving the arm towards the midline of the body is adduction.

The statement is true because a rotator cuff tear refers to the tearing of the rotator cuff tendon. The rotator cuff is a group of tendons and muscles that surround the shoulder joint, and when these tendons tear, it can cause pain, weakness, and limited range of motion in the shoulder. Therefore, the correct answer is true.

Moving the arm away from the midline of the body is Abduction. Abduction refers to the movement of a body part towards the midline of the body. In this case, when the arm is moved away from the midline, it is moving towards the midline, which is abduction.

The supraspinatus muscle is the most commonly affected muscle in cases of rotator cuff tears and impingement. It is located on the top of the shoulder blade and plays a crucial role in shoulder movement and stability. Its tendon passes through a narrow space called the subacromial space, which can become compressed or irritated, leading to impingement and tears. Therefore, the supraspinatus muscle is often involved in these shoulder injuries.

The supraspinatus muscle is responsible for abduction of the arm at the shoulder joint, helping to resist the inferior gravitational forces placed across the shoulder joint, and stabilizing the shoulder joint by keeping the head of the humerus firmly pressed medially against the glenoid fossa of the scapula. However, it does not rotate the head of the humerus medially (internal rotation).

The subscapularis muscle is a powerful defense to the front of the shoulder joint, preventing displacement of the head of the humerus. It is one of the four muscles that make up the rotator cuff and is located on the anterior side of the scapula. Its main function is to internally rotate and adduct the arm, but it also plays a significant role in stabilizing the shoulder joint and preventing dislocation.

The infraspinatus and teres minor muscles are part of the rotator cuff and help hold the humeral head in the glenoid cavity of the scapula. They work together with the posterior deltoid to externally rotate the humerus and also perform adduction, extension, and transverse extension. These muscles play a crucial role in stabilizing the shoulder joint and allowing for various movements of the arm.