Epineuria

Part of speech: noun

Definitions

1. A term referring to the outer layer of connective tissue that encases a peripheral nerve ; or describing multiple such layers in different nerves ; or used to designate this protective sheath in anatomical contexts
2. Denoting the fibrous sheath enveloping an entire peripheral nerve ; signifying the same structure across various nerves ; or referencing this anatomical wrapping in scientific terminology
3. Indicating the protective connective covering surrounding a nerve trunk ; referencing more than one such sheath in anatomical usage ; or the designation for this specific layer in nerve anatomy

Etymology: "Epineuria" is the plural of "epineurium", the name for the tough outer sheath that wraps a bundle of nerve fibres. The singular comes from New Latin, a scientific Latin coined by anatomists and borrowed back into the vocabulary of medicine, and it is built from two Ancient Greek parts: "epi", meaning "upon" or "on top of", and "neuron", meaning "nerve" (the Greek word is "neûron", and in classical use it could also mean sinew or tendon). The pattern is simple. Each nerve is made of many fibres, and the epineurium is the layer that lies on top of the whole bundle, holding it together. The word therefore describes a position, not a substance, and an anatomist could say "epi-" plus "neuron" and be understood at once. Because the parts are ancient but the compound is modern, the word would have meant nothing to a Greek physician, even though every piece of it came from Greek.