Muscle Cell
Muscle Fiber
About the Muscle Cell
Muscle Fiber
Skeletal muscles
Muscle fibers contain repeating contractile bundles that shorten to generate force.
Clinical and real-world context
Muscle fiber architecture links microscopic structure with contraction, fatigue, rehabilitation, and neuromuscular disease teaching.
3 structures to explore
Myofibril
The contracting thread
Each muscle fiber contains hundreds to thousands of myofibrils running its full length, packed tightly together.
A single muscle fiber can be up to 30 cm long.
Sarcolemma
The excitable membrane
The sarcolemma conducts electrical signals that trigger contraction throughout the muscle fiber.
Membrane signals reach deep into fibers through T tubules.
Mitochondria
The endurance supply
Muscle cells need many mitochondria because contraction consumes large amounts of ATP.
Endurance training can increase mitochondrial density.