Ball and socket joint
Encyclopedia
A ball and socket joint(enarthrosis, spheroidal joint) is a joint
Joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...

 in which 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 a 360° angle.

In a ball and socket (spheroid) joint, the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone.

Examples

Examples of this form of articulation are found in the hip, where the rounded head of the femur
Femur head
The femur head is the highest part of the thigh bone . It is supported by the neck of the femur.The head is globular and forms rather more than a hemisphere, is directed upward, medialward, and a little forward, the greater part of its convexity being above and in front.Its surface is smooth,...

 (ball) rests in the cup-like acetabulum
Acetabulum
The acetabulum is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.-Structure:...

 (socket) of the pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...

, and in the glenohumeral joint
Glenohumeral joint
The glenohumeral joint, or shoulder joint, is a multiaxial synovial ball and socket joint and involves articulation between the glenoid fossa of the scapula and the head of the humerus...

 of the shoulder
Shoulder
The human shoulder is made up of three bones: the clavicle , the scapula , and the humerus as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder make up the shoulder joints. The major joint of the shoulder is the glenohumeral joint, which...

, where the rounded head of the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....

 (ball) rests in the cup-like glenoid fossa
Glenoid cavity
The glenoid cavity is a shallow pyriform, articular surface, which is located on the lateral angle of the scapula. It is directed laterally and forward and articulates with the head of the humerus; it is broader below than above and its vertical diameter is the longest.This cavity forms the...

 (socket) of the shoulder blade
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....

. It should be noted that the shoulder includes a second joint
Sternoclavicular articulation
The sternoclavicular articulation is a synovial double-plane joint composed of two portions separated by an articular disc. The parts entering into its formation are the sternal end of the clavicle, the upper and lateral part of the manubrium sterni , and the cartilage of the first rib, visible...

 as well which is a saddle joint
Saddle joint
In a saddle joint the opposing surfaces are reciprocally concave-convex.-Movements:...

.
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