Ball and socket joint

Ball and socket joint
1: Ball and socket joint; 2: Condyloid joint (Ellipsoid); 3: Saddle joint; 4 Hinge joint; 5: Pivot joint;
Capsule of shoulder-joint (distended). Anterior aspect.
Identifiers
TA	A03.0.00.050
Anatomical terminology []

The ball and socket joint (or spheroidal joint) is a type of synovial joint in which the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. The distal bone is capable of motion around an indefinite number of axes, which have one common center. It enables the bone to move in many places (nearly all directions).

An enarthrosis is a special kind of spheroidal joint in which the socket covers the sphere beyond its equator.

Examples of this form of articulation are found in the hip, where the rounded head of the femur (ball) rests in the cup-like acetabulum (socket) of the pelvis, and in the glenohumeral joint of the shoulder, where the rounded head of the humerus (ball) rests in the cup-like glenoid fossa (socket) of the shoulder blade. It should be noted that the shoulder includes a sternoclavicular articulation joint.

Hip

Shoulder

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)