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The capsule of the glenohumeral (shoulder) joint is the articular capsule of the shoulder.It completely surrounds the joint. It is attached above to the circumference of the glenoid cavity beyond the glenoidal labrum, and below to the anatomical neck of the humerus, approaching nearer to the articular cartilage above than in the rest of its extent.
The hardening of the shoulder joint capsule is central to the disease process. This is the result of scar tissue around the joint capsule. [14] There also may be a reduction in synovial fluid, which normally helps the shoulder joint, a ball and socket joint, move by lubricating the gap between the humerus and the socket in the shoulder blade.
The rotator cuff muscles of the shoulder produce a high tensile force, and help to pull the head of the humerus into the glenoid cavity. The glenoid cavity is shallow and contains the glenoid labrum which deepens it and aids stability. With 120 degrees of unassisted flexion, the shoulder joint is the most mobile joint in the body.
The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder make up the shoulder joints .
Each capsule consists of two layers or membranes: an outer (fibrous membrane, fibrous stratum) composed of avascular white fibrous tissue; an inner (synovial membrane, synovial stratum) which is a secreting layer; On the inside of the capsule, articular cartilage covers the end surfaces of the bones that articulate within that joint.
The shoulder joint is composed of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) (see diagram). Two joints facilitate shoulder movement. The acromioclavicular (AC) joint is located between the acromion (part of the scapula that forms the highest point of the shoulder) and the clavicle.
The most important ligament involved in shoulder joint stability is the Inferior Glenohumeral Ligament. During abduction of the arm, the middle and inferior ligaments become taut while the superior ligament relaxes. The radius of curvature of the head of the humerus is greater superiorly than inferiorly, which further stretches these ligaments ...
The shoulder joint is considered a ball-and-socket joint. However, in bony terms the 'socket' (the glenoid fossa of the scapula) is quite shallow and small, covering at most only a third of the 'ball' (the head of the humerus). The socket is deepened by the glenoid labrum, stabilizing the shoulder joint. [1] [2]