fascicle

Fascicle is a term used to describe a small bundle or cluster of parts that function together. The word comes from Latin fasciculus, a diminutive of fascis, meaning bundle.

In anatomy, a fascicle refers to a bundle of fibers within a nerve or a bundle of muscle fibers within a muscle. A peripheral nerve is organized into fascicles, each surrounded by perineurium, with several fascicles making up the full nerve. In skeletal muscles, groups of muscle fibers are enclosed by perimysium to form a fascicle. In the central nervous system, related terms such as fasciculus or lemniscus describe similar bundles of axons or tract-like arrangements.

In botany, fascicle denotes a bundle or cluster of leaves, flowers, or vascular elements arising from a common point. A well-known example is the fascicle of pine needles, where two to five needles are grouped together on a short shoot. The term can also describe clustered leaves or inflorescences in other plant groups.

In publishing, a fascicle is a separately published installment of a larger work, such as a monograph or a multi-volume encyclopedia. Fascicles may be issued periodically and later combined into a single volume.

See also: fasciculus, fasciculation, bundle.