19
The three tiny bones present in middle ear are called ear ossicles. Write them in correct sequence beginning from ear drum.
Explanation
Each middle ear contains three tiny bones, named, i.e., malleus, incus and stapes which are collectively called as ear ossicles.
20
What is the difference between the matrix of bones and cartilage?
Explanation
Difference between the matrix of bones and cartilage
| Matrix of Bones | Matrix of Cartilage |
|---|---|
| Matrix of bones has an inflexible material, the ossein. | Matrix of cartilage has a flexible material, the chondrin. |
| Matrix of bones contains calcium salts. | Calcium salts may or may not be present in matrix. |
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21
Which tissue is afflicted by myasthenia gravis? What is the underlying cause.
Explanation
Myasthenia gravis is an autoimmune disorder of skeletal muscle, affecting neuromuscular junction, that leads to fatigue, weakening and paralysis of the skeletal muscle.
22
How do our bone joints function without grinding noise and pain?
Explanation
The presence of synovial fluid, between articulating surface of the two bones enclosed within synovial cavity of synovial joints to makes our joints to function without grinding noise and pain.
23
Give the location of a ball and socket joint in a human body
Explanation
Ball and socket joint are present between humerus and pectoral girdle. These joints allows free movement of bone in all direction. e.g., shoulder jointds (humerus bone in socket of pectoral girdle) and hip joints femur bone in socket pelvic girdle.
