noun
perineurium
Anatomical term for the protective sheath surrounding a bundle of nerve fibers (fascicle).
神経周膜は神経線維束を包む結合組織の層です。
The perineurium is a layer of connective tissue that surrounds a bundle of nerve fibers.
Compound of 神経 (nerve) + 周 (surrounding) + 膜 (membrane), directly describing its anatomical function.