õlaliiges

Õlaliiges, also known as the glenohumeral joint, is the ball-and-socket joint connecting the humerus (upper arm bone) to the scapula (shoulder blade). It is the most mobile joint in the human body, allowing for a wide range of motion in all planes, including flexion, extension, abduction, adduction, internal rotation, and external rotation. This extensive mobility, however, comes at the cost of inherent joint stability.

The joint is comprised of the glenoid cavity, a shallow socket on the scapula, and the humeral head, a rounded prominence of the humerus. The glenoid cavity is deepened by the glenoid labrum, a ring of fibrocartilage that enhances stability. The joint capsule, a fibrous sleeve, encloses the glenohumeral joint, providing structural support and containing synovial fluid for lubrication. Ligaments, such as the glenohumeral ligaments, further reinforce the capsule and limit excessive movement.

Surrounding the joint are several muscles and their tendons, collectively known as the rotator cuff. These muscles, including the supraspinatus, infraspinatus, teres minor, and subscapularis, play a crucial role in stabilizing the humeral head within the glenoid cavity and initiating and controlling arm movements. The bursa, small fluid-filled sacs, reduce friction between tendons and bones during movement.

Due to its high mobility and reliance on soft tissues for stability, the shoulder joint is susceptible to various injuries, including dislocations, rotator cuff tears, and impingement syndrome.