Several fascicles may be in turn bundled together with a blood supply and fatty tissue within yet another sheath, the epineurium.

The perineurium is composed of connective tissue, which has a distinctly lamellar arrangement consisting of one to several concentric layers.

The perineurium is a smooth, transparent tubular membrane which may be easily separated from the fibers it encloses.

A sort of lesion called axonotmesis[3] can happen, where the axon of the nerve is damaged while the integrity of the perineurium and epineurium is preserved.

In that case, there will be a loss of neural transmission which will be causing a diminished response in the distal part of the nerve.