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 In vertebrate anatomy, the hip, or coxaLatin ''coxa'' was used by Celsus in the sense "hip", but by Pliny the Elder in the sense "hip bone" (Diab, p 77) (: ''coxae'') in medical terminology, refers to either an anatomical region or a joint on t ...

, where the round head of the femur (ball) rests in the cup-like

acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur meets with the pelvis at the acetabulum, forming the Hip#Articulation, hip joint. Structure The ...

(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 The shoulder joint (or glenohumeral joint from Greek ''glene'', eyeball, + -''oid'', 'form of', + Latin ''humerus'', shoulder) is structurally classified as a synovial joint, synovial ball-and-socket joint and functionally as a diarthrosis and m ...

, where the rounded upper extremity of the humerus (ball) rests in the cup-like glenoid fossa (socket) of the

shoulder blade The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

.And the phalanges (toes, fingers)
Introduction to Joints: Synovial Joints - Ball and Socket Joints
(The shoulder also includes a

sternoclavicular joint The sternoclavicular joint or sternoclavicular articulation is a Synovial joint, synovial Saddle joint, saddle joint between the sternum#Manubrium, manubrium of the sternum, and the clavicle bone, clavicle, and the first costal cartilage. The joi ...

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

* * {{Authority control Joints