NCERT Solutions for Class 9th Science Chapter 3 .5 Types of Joints — Pause and Ponder

Book page 403 Updated on2026-09-08

Q5.
Look at the picture given below (Fig. 3.17). Carefully observe the various poses of classical and folk dances of India. Can you identify which joints are involved? Also, what type of movement each joint allows?
Answer

Almost every joint in the body appears somewhere in Fig. 3.17. Look at what each dancer is doing and name the joint by the movement, not by the pose.

What you can see in the posesJoint involvedTypeMovement it allows
Arms raised above the head, swung out sideways, circledShoulderBall and socketForward, backward, sideways and circular movement of the whole arm
One leg lifted to the side and swung out (as in the first and second poses)HipBall and socketFree movement of the thigh in all directions
Elbow bent sharply to hold a mudra near the shoulderElbowHingeBending and straightening the forearm in one plane
Deep araimandi knee bend, weight on a bent kneeKneeHingeBending and straightening the leg; the kneecap protects the joint
Standing on the ball of the foot, toes pointed, heel struck on the floorAnkle and toe jointsHingeUp-and-down movement of the foot; the tendon at the heel transmits the pull
Head turned side to side, the classic greeva movementSkull on the backbonePivotRotation of the head, side to side like a doorknob
Fingers held in precise mudrasFinger jointsHingeBending of each finger segment; the muscles are in the forearm and pull through long tendons
Skull itself, holding its shape through every jumpBones of the skullFixedNo movement — the brain, eyes and ears stay protected
Why classical dance is such a good demonstration: a dance pose holds a joint at the extreme of its range, so the limit set by the joint's shape becomes obvious. The arm can be raised straight overhead — a ball and socket allows that. The knee cannot bend backwards no matter how the dancer moves — a hinge forbids it. And nothing is possible without muscles pulling on bones through tendons while ligaments keep the bones in place.
Try This: stand in one of the poses and, without moving, list the joints you are holding bent. Then try the same pose with your knees locked straight — you will find you cannot balance, because the small adjustments of the ankle and knee are what keep you upright.
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