question_answer 11)

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

Answer:

(a) A joint in which the rounded end of one bone fits into the hollow space of other bone is called ball and socket joint. It allows movements in all the directions. Joints between upper arm and shoulder, thigh and hip are examples of ball and socket joints. (b) In skull, only the lower jaw is movable. All the other bones of skull are immovable. (c) Our elbow cannot move backwards because the elbow has a hinge joint that allows movement in only one direction.