Nerves or the nervous system.
[Greek neuron, nerve, sinew, tendon.]
This form appears widely in medicine and related fields. Neuralgia (Greek algos, pain) is a pain along the course of a nerve, often in the head or face; neurasthenia is an ill-defined medical condition characterized by lassitude, headache, and irritability; the adjective neuromuscular refers to nerves and muscles. Neurology is the study of the anatomy, functions, and organic disorders of nerves and the nervous system. A neuron is a specialized cell transmitting nerve impulses; a neuroleptic drug tends to reduce nervous tension by depressing nerve functions. A neurosis in medical usage is a relatively mild mental illness that is not caused by organic disease, while in non-technical use it refers to excessive and irrational anxiety or obsession (adjective neurotic). The form appears in several compound terms for medical sub-specialities, such as neurophysiology and neuropharmacology. The usual adjective is neural.