Final answer:
Muscle fibers are organized into fascicles by a layer of connective tissue called the perimysium.
Step-by-step explanation:
Inside each skeletal muscle, muscle fibers are organized into individual bundles called fascicles. These fascicles are divided by a middle layer of connective tissue called the perimysium. The perimysium acts as a scaffold and provides support and protection to the muscle fibers within each fascicle. This organizational structure allows the nervous system to control specific movements by activating subsets of muscle fibers within a fascicle.