Muscle fascicles bundle muscle fibers together for extra strength, allowing the muscle to exert more force. The diameter and length of muscle fascicles vary depending on the specific function of the muscle.
A muscle fascicle is a group of muscle fibers or cells that are bound together by a membrane of connective tissue called perimysium. The fascicle is much stronger than a single muscle fiber in the same way that a rope is much stronger than a single thread. Muscle fascicles range from a few fibers to over 100. Fascicles are arranged in parallel, pennate or circular patterns. Parallel fascicle groups allow for an extended range of motion. Pennate patterns exert the largest amount of force but have a small range of motion. Circular fascicle groups open and close openings.