the muscles

THE MUSCULAR TISSES
?These tissues form the muscles.
? They are made up of muscle cells, which are
typically elongated and arranged in parallel
array, allowing them to work together
effectively and they are called muscles
fibers .
?Three kinds of muscles are known in the animal
body: -
.Striated or Skeletal Muscles-1
?Note the striated muscle fibers which appear as large
elongated cylindrical cell, each showing a large number of
fine alternating dark and light cross striations commonly
known as the dark bands (myosin filaments) and light
bands (actin filaments), they called (A,I) bands and
contains a large number of peripherally situated nuclei.
?The striated muscles are usually found connected to the
skeleton and their movement is controlled by the will of the
animal. Hence they are called skeletal or voluntary
muscles.

.Unstriated or Smooth Muscles- 2
? In which the cells do not exhibit cross striations.
Note the bundles of unstriated muscle fibers.
Each fiber is:
? a long,
? spindle shaped cell with pointed ends
? a thickened central part housing the nucleus .
? The unstriated muscles are usually found in the
walls of the viscera and work without the
interference of the will of the animal. Hence they
are also called visceral or in voluntary
muscles . (i.e. Alimentary canal, blood vessels).
?

.Cardiac Muscles- 3
? Note that the cardiac muscle fibers are also
cylindrical, but not much elongated.
? Each fiber has one ovoid central nucleus, the
cardiac fiber branch and unite with each other .
Every two connected fibers have a darkly stained
transverse band in between them known as the
intercalated discs , and contains alternating dark
and light bands . The cardiac muscles are found
only in the wall of the heart and contract
rhythmically.