The endomysium surrounds which structure?

• A. A bundle of muscle fibers
• B. A nerve fiber
• C. A single muscle fiber
• D. The entire muscle

Answer: (C)

The endomysium is the delicate connective tissue that surrounds a single skeletal muscle fiber. It wraps each muscle cell just beneath the sarcolemma, separating it from its neighbors and containing capillaries and sometimes satellite cells that aid in repair. This thin sheath helps distribute forces generated by one fiber to the surrounding extracellular framework and supports exchange of nutrients and signals.

Understanding the surrounding layers helps: the perimysium groups fibers into bundles called fascicles, and the epimysium encloses the entire muscle. The endomysium is not around a nerve fiber—that’s the role of the endoneurium in nerves—nor around a bundle of fibers (that’s the perimysium), nor around the whole muscle (that’s the epimysium). So the endomysium specifically surrounds a single muscle fiber.