NCERT Solutions for Class 9th Science Chapter 3 .4.1 The musculoskeletal system in action — Activity 3.5: Let us observe

Book page 393 Updated on2026-09-08

Q1.
Move different parts of your body and observe what movement(s) it can make.
Answer

Here is Table 3.5 filled in. The book gives the elbow row (No, No, Yes) as your model; the rest follow from the type of joint at each place.

Body partComplete rotationPartial rotationBendingTurning, side-raising, up-down or any other movementJoint
ElbowNoNoYesOnly bending and straightening, in one planeHinge
ShoulderYesYesYesForward, backward, sideways and circularBall and socket
KneeNoNoYesBending and straightening only; kneecap protects itHinge
NeckNoYesYesSide-to-side turning (‘no’), nodding up and downPivot
FingersNoNoYesBending at each joint; the thumb base also swingsHinge
ToesNoNoYesBending up and down (that is what you feel in the tendon at the heel)Hinge
WristNoYesYesUp-down, side-to-side and a small circling movementGliding joint between many small bones
Why the answers are not all the same: the movement a part can make is decided by the shape of the bone ends at the joint. A rounded head sitting in a shallow socket (shoulder) can swing in every direction. A cylinder held in a curved notch (elbow, knee) can only swing in one plane, like a door on its hinge. A peg turning in a ring (neck) can only rotate. Bones fused edge to edge (skull) cannot move at all. Structure fixes function here just as it does in a tissue.
Tip: a joint by itself cannot move anything. Muscles pull on the bones through tendons; the joint only decides which way that pull is allowed to move the bone.
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