Which term refers to a bundle of muscle fibers surrounded by perimysium, with the epimysium surrounding multiple such bundles to form a complete muscle belly?

• A. Striated fibers that are attached to bone and are responsible for movement of the skeleton at its joints
• B. A fluid-filled bag that cushions tendons
• C. Striated fibers that make up the walls of the heart
• D. Muscle fascicles

Answer: (D)

Muscle organization is layered: individual muscle fibers are wrapped in endomysium, groups of fibers bound together form a fascicle and are wrapped by perimysium, and several fascicles together are encased by the epimysium to create the whole muscle belly. The bundle of muscle fibers surrounded by perimysium, with the epimysium around multiple such bundles, is exactly a muscle fascicle. This arrangement allows coordinated force transmission and houses nerves and blood vessels within the connective tissue layers. The other descriptions point to general skeletal muscle function, a tendon sheath, or cardiac muscle, none of which define this specific bundle envelopment.