Tissue

• Muscular tissue consists of elongated cells, also called muscle fibres.
• This tissue is responsible for movement in our body.
• Muscles contain special proteins called contractile proteins, which contract and relax to cause movement
• On the basis of their location, structure and function, there are following three types of muscle fibres:
  • Striated muscles
  • Smooth muscles
  • Cardiac muscles

Types Of Muscular Tissue

Skeletal or Striated or voluntary Muscles

• Striated muscles are also known as striped, skeletal or voluntary muscles.
• They are mostly attached to bones and help in body movement.
• Since the entire muscle fibres show alternate dark and light stripes (striations or bands), they are called striped muscles.
• They are attached to the bones and are responsible for body movements.
• They are also called voluntary muscles.
• Its nuclei are peripheral in position.
• The cells of this tissue are long, cylindrical, unbranched and multinucleate having many nuclei.

Occurrence:

• Striated muscles occur in the muscles of limbs (e.g, biceps and triceps of arms), body wall, face, neck, etc.
• Striated muscles present in tongue, pharynx, diaphragm and upper part of oesophagus.

Functions:

• Striated muscles are powerful and undergo rapid contraction. These muscles can get tired and may need rest.
• Striated muscles provide the force for locomotion and all over voluntary movements of the body.

Smooth Muscles:

• Smooth muscles are also known as unstriated, visceral or involuntary muscles.
• Smooth muscles occur as bundles or sheets of elongated fusiform or spindle-shaped.
• The cells are long with pointed ends and uninucleate (having a single nucleus).
• They are also called unstriated muscles.

Occurrence:

• Smooth muscles are found I the walls of the hollow (tubular) visceral organs except that of the heart, and so are called visceral muscles.
• They occur in the wall of alimentary canal and internal organs, ducts of glands, urogential ducts and blood vessels.
• They are also found in the iris of the eye, in ureters and in the bronchi of the lungs.

Functions:

• Smooth muscles do not work (contract) according to our will, so they are also called involuntary muscles.
• Smooth muscles cause the characteristic peristaltic movements in the tubes.
• In some organs, smooth muscles contract throughout the organs to produce extrusive movements as in the urinary bladder, the gall bladder and the uterus.

Cardiac Muscles

• Cardiac muscles show characteristics of both smooth and striated muscles.
• Heart muscle cells are cylindrical, branched and uninucleate.
• Cardiac muscles have stripes of light and dark bands.
• These muscle fibres show densely stained cross-bands called intercalated impulse
• The cardiac muscles occur in the heart.

Functions:

• Cardiac muscles contract and relax rapidly, rhythmically and tirelessly throughout a life time. They contract endlessly from early embryonic stage until death.
• The contraction and relaxation of the heart muscles help to pump and distribute blood to various parts of body.

Comparison of smooth, skeletal and cardiac muscles