Which joint forms the ball-and-socket articulation of the shoulder?

Which joint forms the ball-and-socket articulation of the shoulder?

• A. Glenohumeral joint
• B. Acromioclavicular joint
• C. Radiocarpal joint
• D. Humeroulnar joint

Answer: (A)

The shoulder’s ball-and-socket arrangement is provided by the glenohumeral joint. Here, the rounded head of the humerus sits in the shallow glenoid cavity of the scapula, forming a true ball-and-socket that allows movement in many directions—flexion/extension, abduction/adduction, rotation, and circumduction. The socket is deepened a bit by the glenoid labrum and stabilized by the joint capsule, ligaments, and the rotator cuff muscles, which together enable vast freedom of motion while keeping the joint functional. The other joints mentioned don’t form a ball-and-socket: the acromioclavicular joint is a plane-type joint between the clavicle and acromion, the radiocarpal joint is the wrist between the radius and carpal bones, and the humeroulnar joint is the elbow hinge joint.

The shoulder’s ball-and-socket arrangement is provided by the glenohumeral joint. Here, the rounded head of the humerus sits in the shallow glenoid cavity of the scapula, forming a true ball-and-socket that allows movement in many directions—flexion/extension, abduction/adduction, rotation, and circumduction. The socket is deepened a bit by the glenoid labrum and stabilized by the joint capsule, ligaments, and the rotator cuff muscles, which together enable vast freedom of motion while keeping the joint functional. The other joints mentioned don’t form a ball-and-socket: the acromioclavicular joint is a plane-type joint between the clavicle and acromion, the radiocarpal joint is the wrist between the radius and carpal bones, and the humeroulnar joint is the elbow hinge joint.