Ventral view of the right human shoulder (glenohumeral) joint.
In this joint the head of the humerus articulates with the glenoid cavity of the scapula.
The shoulder joint is the most mobile ball-joint of the human body. The ball-shaped head of the humerus articulates with the oval glenoid cavity. The glenoid cavity is relatively small, compared to the head of the humerus and therefore does not enclose the head completely (as it is the case in the hip joint).
The contact-surface between the two joint-partners is enlaged by the 3-4 mm wide glenoid labrum (lip) that consists of fibrous cartilage and is attached to the rim of the glenoid cavity.
The joint capsule of the shoulder joint is relatively wide and lax. Caudally there is (in a relaxed position) a reserve zone of about 1 cm (axillar recessus).
The following forms of movement are possible: Anteversion, retroversion, abduction, adduction, internal rotation, external rotation.