Question

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Answer 1

Ans: Option (d) all of these

Explanation: All the given factors influence the stability of the joints. let's understand them one by one:

(a) The shape of the articular surface:

The articular surface of the joint can be defined as the surface where the two bones are in contact with each other. The joint is more stable when:

• the articular surface is large
• bones are properly fit with each other at the joint
• socket is deep

The hip joint that is an example of the ball and socket joint is very stable joint because the socket is deep and bones in contact are perfectly fit with each other. On the other hand, the shoulder joint is less stable because the socket (present in scapula) is shallow and the ball (present in humerus) is bigger than the socket.

(b) presence of strong reinforcing ligaments:

ligaments hold the bones at their place (at the joints) during movements. Thus the presence of strong reinforcing ligaments will increase the stability of the joints.

(c) the tone of surrounding muscles:

The tone of the surrounding muscles plays a very important role in maintaining the stability of the joints. For example at the shoulder joint which is an example of the ball and socket joint the rotator cuff muscles keep the head of humerus bone in the socket of the scapula. In the old age or due to any other reason if muscle tone is reduced the stability of the shoulder joint (or any other joint) will be reduced.