A funiculus is a small bundle of axons (nerve fibres), enclosed by the perineurium.

A small nerve may consist of a single funiculus, but a larger nerve will have several funiculi collected together into larger bundles known as fascicles.

Fascicles are bound together in a common membrane, the epineurium.

[1][2] Funiculi in the spinal cord are columns of white matter.

[3][4] Examples include: This article incorporates text in the public domain from page 728 of the 20th edition of Gray's Anatomy (1918)