Trigeminal nerve

The trigeminal nerve (the fifth cranial nerve, also called the fifth nerve or simply V) is responsible for sensation in the face. It is similar to the spinal nerves C2-S5 that are responsible for sensation in the rest of the body. Sensory information from the face and body is processed by parallel pathways in the central nervous system.

The etymology of trigeminal is often given as Latin tri (three) + gemini (twins). However, "three twins" is not the intended meaning. The Oxford English Dictionary (2nd edition, 1989) gives the etymology as Latin trigeminus (born three at birth), which in turn derives from tri + geminus (born at the same birth). This makes a certain amount of sense, since the plural of geminus (gemini) then implies "twins," while trigeminal implies "three parts."