- The shoulder has two main bones: the scapula (the shoulder blade) and the humerus (the long bone of the upper arm). The end of the scapula, called the glenoid, is a socket into which the head of the humerus fits to form a flexible ball-and-socket joint. The shoulder joint is cushioned by cartilage that covers the face of the glenoid socket and head of the humerus. The joint is stabilized by a ring of fibrous cartilage around the glenoid socket that is called the labrum. Ligaments connect the bones of the shoulder and tendons join the bones to surrounding muscles. The biceps tendon attaches the biceps muscle to the shoulder and helps stabilize the joint. Four short muscles that originate on the scapula pass around the shoulder where their tendons fuse together to form the rotator cuff. The scapula is an unusually shaped bone. It extends up and around the shoulder joint at the rear to create a roof called the acromion and around the shoulder joint at the front to constitute the coracoid process.
* * *1. The lateral portion of the scapular region, where the scapula joins with the clavicle and humerus and is covered by the rounded mass of the deltoid muscle. 2. In dentistry, the ledge formed by the junction of the gingival and axial walls in extracoronal restorative preparations. [A.S. sculder]- frozen s. SYN: adhesive capsulitis.
* * *shoul·der 'shōl-dər n1) the laterally projecting part of the human body formed of the bones and joints with their covering tissue by which the arm is connected with the trunk2) the two shoulders and the upper part of the back usu. used in pl.
* * *n.the ball-and-socket joint (see enarthrosis) between the glenoid cavity of the scapula and the upper end (head) of the humerus. It is a common site of dislocation. The joint is surrounded by a capsule closely associated with many tendons: it is the site of many strains and inflammations ('cuff injuries').
* * *shoul·der (shōlґdər) the junction of the upper limb and trunk; also that part of the trunk that is bounded at the back by the scapula. See also regio deltoidea.
Medical dictionary. 2011.