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MUSCULAR TISSUE

• It is one of the four basic types of tissues primarily responsible for
locomotion and movement of the various body parts.

General features
• Muscle cells are long and narrow; therefore they are called muscle fibers or

myofibers.
• Muscle fibers are highly specialized for contractility, which occurs due to

the presence of contractile proteins within their cytoplasm.
• Muscle fibers originate primarily from the mesoderm, except the muscle of

the iris, and myoepithelial cells that are ectoderm.
• Special terms are used for muscle fibers: plasmalemma=sarcolemma;

cytoplasm=sarcoplasm; endoplasmic reticulum=sarcoplasmic reticulum;
mitochondria=sarcosomes.
• Muscle tissue is a composite tissue where it contains a minimal amount of
connective tissue beside its principal cells.
• There are three types of muscle tissue: skeletal, cardiac and smooth
muscles.

Skeletal muscle (Striated and voluntary myofibers)

• They are found in all skeletal muscles, tongue larynx, pharynx and eye.
• It is called skeletal because its contraction moves some parts of the

skeleton; voluntary because its contraction is under conscious control, and
striated because under microscope, its fiber shows alternating dark and light
bands called cross-striation.
• A skeletal muscle is composed of skeletal myofibers and connective tissue.
• A sheath of dense connective tissue called epimysium encloses the entire
muscle.

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