CBSE Class 9 Answered

The muscles are of 3 types - Striated, nonstriated and Cardiac.

The striated muscle cells are long, cylindrical, non-tapering and unbranched. Each muscle cell is multinucleate. The nuclei are present just below the surface membrane.

The alternate light and dark striations are also present in the striated muscles.

These muscles are also called skeletal muscles since they are mostly attached to bones and help in body movements. Striated muscles can carry out forceful work. But they can be tired and need rest.

Smooth muscles are found in the walls of the visceral organs, except heart, hence they are also called visceral muscles.

These muscles are found in the wall of alimentary canal and internal organs. They also occur in the iris of eye, ureters and in the bronchi of the lungs. Other body parts like ducts of glands and blood vessels also show the presence of smooth muscles.

The cells of smooth muscle are long and spindle shaped . Spindle shaped means pointed at both ends and broad in the middle. They are present as bundles in the muscle and are held together by connective tissue. Each cell has a single centrally located nucleus.

Cardiac muscles are composed of branched fibres or cells. These cells are cylindrical and uninucleate.

Cardiac muscles have stripes like striated muscles. In addition, there are present densely stained cross-bands called intercalated discs. These are the regions of joining of individual muscle cells to one another.

 Cardiac muscles are found in the heart. Cardiac muscles contract and relax rhythmically throughout life. This helps to pump and distribute blood to various parts of the body.