6 grade science> science-questions...

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?

Hrishant Goswami , 12 Years ago

Grade 10

3 Answers

Deepak Patra

Ball and socket joint is a movable joint. It consists of a bone that has a round head, which fits into a cup like depression of another bone. This helps the bone to rotate freely. Examples of such joints are hip and shoulder joints.

Mandible bone which forms the lower jaw is the only skull bone that is movable.

The elbow has a hinge joint. This type of a joint allows the movement in one plane only. Therefore, our elbow cannot move backwards.

Last Activity: 12 Years ago

Adarsh

A ball and socket joint is a joint in which the ball-shaped surface of a bone fits into the cup-like indentation of another bone.
Lower jaw bone or mandible is the only movable bone in the skull.
Elbow joint is composed of hinge joint. These joints allow movement in one plane and up to 180° only. Hence, we cannot move our elbows backwards.

Last Activity: 10 Years ago

Ayan

(a)The rounded end of the one bone fits into the hollow space of other bone. This is calleda ball and socket joint. Ball and socket joints allow movements in all the directions, e.g. shoulder and hip can be moved in all directions.

(b)In the skull, only the lower jaw is movable.

(c)Our elbow cannot move backward because the elbow has a hinge joint that allows movement in only one direction back and forth.

Last Activity: 8 Years ago