Class Notes NCERT Solutions for CBSE Students
Question: Explain various kinds of joints found in our body and give example of each.
Answer: There are five types of joints in our body:
(i) Fixed joints: Those joints which do not allow movement are called fixed joint.
(ii) Ball and socket joint: This joint allows movement in all directions. The rounded end of one bone fits into the hollow space of other bone. For example, joint between upper arm and shoulder.
(iii) Pivotal joint: This type of joint allow movement in all planes, i.e. up and down, side and other planes. For example, head.
(iv) Hinge joint: The joint which allows movement only in one plane is called hinge joint. For example, fingers, knees.
(v) Gliding joint: These joints allow only a limited amount of movement of sliding nature of cartilage. For example, the joints of backbone.
Question: What are joints? Write the names of various types of joints.
Answer: The places where two parts of the body seem to be joined together are called joints. There are following types of joints:
- Ball and socket joints
- Pivotal joints
- Hinge joints
- Fixed joints
- Gliding joints
Question: How do the muscles work?
Answer: The muscles work in pairs. When one of them contracts, the bone is pulled in that direction, the other muscle of the pair relaxes. To move the bone in the opposite direction, the relaxed muscle contracts to pull the bone towards its original position, while the first relaxes.A muscle can only pull. It cannot push.
