Muscle fascicle

A muscle fascicle (or fasciculus) is a bundle of skeletal muscle fibres (muscle cells) surrounded by a connective tissue sheath called the perimysium.

Each fascicle contains multiple muscle fibres, which are individually enclosed by endomysium. Groups of fascicles together form the whole muscle, which is surrounded by an outer connective tissue layer called the epimysium.

The arrangement of fascicles within a muscle (e.g., parallel, pennate, convergent, circular) determines the muscle’s shape, range of motion, and strength.

Example

In a bipennate muscle like the rectus femoris, fascicles are arranged on both sides of a central tendon, allowing powerful contractions within a limited range.