The ball-and-socket joint (or spheroid joint) is a type of
synovial joint
A synovial joint, also known as diarthrosis, joins bones or cartilage with a fibrous joint capsule that is continuous with the periosteum of the joined bones, constitutes the outer boundary of a synovial cavity, and surrounds the bones' articulati ...
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. This enables the joint to move in many directions.
An enarthrosis is a special kind of spheroidal joint in which the socket covers the sphere beyond its equator.
[Platzer, Werner (2008) ''Color Atlas of Human Anatomy'', Volume 1]
p.28
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Examples of joints
Examples of this form of articulation are found in the hip, where the round head of the femur (ball) rests in the cup-like acetabulum (socket) of the pelvis
The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...
; and in the shoulder joint, where the rounded upper extremity of the humerus (ball) rests in the cup-like glenoid fossa (socket) of the shoulder blade.[And the phalanges (toes, fingers)]
Introduction to Joints: Synovial Joints - Ball and Socket Joints
(The shoulder also includes a sternoclavicular joint.)
Ball and Socket Joint Animation
Diagrams
Kugelgelenk.jpg, Hip
Gray327.png, Shoulder
Ball and Socket Joint (Hip joint).svg, Details of hip joint.
References
External links
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Joints