Ball and socket joint

A ball joint ( articulatio spheroidea ) is referred to a joint in the mechanical and in the anatomy in which the joint head has a spherical shape. The mating piece, which surrounds the head, depending on the joint to varying degrees, is referred to as a socket or ball socket. This geometry is basically a ball joint movable in all directions ( triaxial). There are only rotational but not translational movements possible.

Anatomy

An example of a ball joint in the anatomy of the shoulder joint ( articulatio humeri ). A special form of the ball joint is the joint nut ( enarthrosis spheroidea ). In this, the socket grips the rod end on the equator beyond. Thus, the movements are limited in their amplitude. In mammals, the hip joint is constructed in this way.

Although both ball and nut joint in principle vielachsig, this movement may be substantially reduced by the arrangement of the muscles. Thus, the shoulder joint is in many, constantly advancing, four-footed mammals move with their reduced shoulder girdle only in one axis ( flexion and extension ).

Worn or damaged ball joints can be reconstructed as a prosthesis made ​​of stainless steel and used operationally.

Technology

In automotive engineering ball joints are used in particular in the area of ​​axle steering use where both the steering movement and the spring movement must be transferred to a mobile device.

Other applications:

• Ball joint head of a tripod in the film and Photography

The king pin of a trailer hitch of a car or truck tractor has the same freedoms in motion as a ball joint, but is separable.