Which statement is true about muscle fascicles?

• A. They are surrounded by perimysium
• B. They surround individual muscle fibers
• C. They make up the outer layer around the entire muscle
• D. They slip between myofilaments

Answer: (A)

Muscle organization relies on three connective tissue layers: endomysium around each individual muscle fiber, perimysium wrapping a group of fibers to form a muscle fascicle, and epimysium surrounding the entire muscle. A fascicle is exactly that bundle of fibers enclosed by perimysium, which is why this statement is true. The other options mix up these layers: endomysium surrounds single fibers, not the fascicle; epimysium is the outer layer of the whole muscle, not the fascicle; and fascicles don’t slip between myofilaments, since myofilaments are the contractile proteins inside each fiber, organized within sarcomeres. The perimysium also carries nerves and blood vessels to supply the fibers inside each fascicle.