Question

4. Answer the following:
(a) What is a ball and socket joint?
(b) Which of the skull bones are movable?
(c) Why can our elbow not move backwards?​

Answer 1

Answer:

In this, a bone with a round head fits into the hollow space of another bone. This makes the bone to rotate freely. For example, bones of the hip and shoulder can move in all directions due to ball and socket joints. (b) Lower jaw bone (Mandible bone) is the only skull bone that is movable.

Answer 2

Answer:

a) Ball-and-socket joint, also called spheroidal joint, in vertebrate anatomy, a joint in which the rounded surface of a bone moves within a depression on another bone, allowing greater freedom of movement than any other kind of joint.

b) The only bone in your skull that forms freely movable joints is your mandible, or jawbone.

c) Our elbow cannot move back because it has a hinge joint which allows the movement in one plane only.