The three main types of muscle fibers are striated (or skeletal), smooth, and cardiac. Striated muscle fibers are long, cylindrical, and multinucleated, with a striped appearance due to the arrangement of muscle proteins. Smooth muscle fibers are spindle-shaped, uninucleated, and lack striations. Cardiac muscle fibers are branched, uninucleated, and possess a faint striation pattern, similar to striated muscle, but with intercalated discs connecting them.
Striated (Skeletal) Muscle Fibers:
Shape: Cylindrical, long, and multinucleated.
Nuclei: Multiple nuclei located along the length of the fiber.
Appearance: Striated (striped) due to the arrangement of actin and myosin filaments.
Function: Voluntary movement, posture, and body support.
Smooth Muscle Fibers:
Shape: Spindle-shaped (tapering at both ends).
Nuclei: Single nucleus located in the center of the fiber.
Appearance: Non-striated (lack stripes).
Function: Involuntary movement of internal organs, like the stomach, intestines, and blood vessels.
Cardiac Muscle Fibers:
Shape: Branched, cylindrical, and uninucleated.
Nuclei: Single nucleus located in the center of each fiber.
Appearance: Faintly striated, similar to striated muscle, but with intercalated discs (specialized cell junctions) connecting the fibers.
Function: Pumping of blood by the heart.