Nerve fascicle
A nerve fascicle is a bundle of nerve fibers belonging to a nerve in the peripheral [nervous system]. A nerve fascicle is also called a fasciculus, as is a nerve tract in the central nervous system.
A nerve fascicle is enclosed by perineurium, a layer of fascial connective tissue. Each enclosed nerve fiber in the fascicle is enclosed by a connective tissue layer of endoneurium. Bundles of nerve fascicles are called fasciculi and are constituents of a nerve trunk. A main nerve trunk may contain a great many fascicles enclosing many thousands of axons.
In the central nervous system, a bundle of nerve fibers is called a nerve tract. In neuroanatomy, different tracts in the spinal cord are bundled into fasciculi such as the medial [longitudinal fasciculus]. In the spinal cord, fasciculi are bundled into columns called funiculi such as the anterior funiculus.