Structure of Muscle

Because muscle is converted to meat post slaughter it serves as a raw material for the meat industry
and hence its composition & structure are likely to influence the overall meat quality. It is therefore
important to understand the structure and composition of muscle. In any living system there is a basic unit of
life and that is cell. ( It is assumed here that students registering themselves for this course are aware of the is
structure of cell and what their functions . If one doesn`t then please refer to books that deal with it - - list
appendix at 1A) Cells having similar specialized functions form together and lead to formation of organs or
tissues. Based on such specializations there are three different types of muscles in a meat animal -
1.Striated voluntary or Skeletal muscles.
2. Striated involuntary or Cardiac muscles.
3.Smooth muscles or involuntary muscles.

Let us have a look at these so as to know how they are different from each other-

As now we know that skeletal muscles constitute the bulk of a slaughtered animals muscle mass therefore
special emphasis shall be laid upon the structure and organization of skeletal muscles.

Skeletal muscle:
1.Muscle fiber is the structural unit of skeletal muscle.
2.Muscle fiber constitutes 75-92% of skeletal muscle volume.
3.The rest is contributed by nerve fibers blood vessels,connective tissue and the

If you look at a cross section you will see following important layers holding different structural elements together -

1.Epimysium-It is connective tissue sheath surrounding the entire muscle.
2.Perimysium– A layer beneath epimysium which divide the muscle fibers into small groups or fasciculi
( These groups are also known as primary bundles. When few primary bundles come together they form
secondary bundles and secondary bundles coming together leads to formation of tertiary bundles.)
3. Endomysium– The layer beneath perimysium with surrounds each muscle fiber individually. These are very
thin strands. ( endomysium should not be confused with sarcolemma or muscle cell membrane

The epimysium , perimysium and endomysium serve as the structural basis for skeletal muscles. They conduct
the vascular and neural supply to and from the muscle. Larger nerves and blood vessels lie at the periphery of
perimysium and between the adjacent fasciculi . The size of fasciculi, in fact, has bearing on the texture of the
muscle i.e. muscles engaged in lighter activities have fine texture and it is reverse for the heavier muscles or
muscles which have to work more.