The structure indicated is the epineurium
of a nerve. Nerves are surrounded by three layers
of connective tissue:
is a delicate layer of connective tissue which surrounds individual axons. Collections of axons are known as nerve fascicles
; the perineurium
surrounds each nerve fascicle, and consists of several concentric layers. The epineurium
is the outermost layer of connective tissue which encloses the whole nerve. It is composed of dense irregular connective tissue
and encloses all the nerve fascicles together with any blood vessels which supply the nerve.