what are nerves
Medical Definition of Nerve Nerve: A bundle of fibers that uses electrical and chemical signals to transmit sensory and motor information from one body part to another. The fibrous portions of a nerve are covered by a sheath called myelin and/or a membrane called neurilemma. (Note that entries for specific nerves can be found under the names of the particular nerves. For example, the optic nerve is not under 'nerve, optic' but rather under 'optic nerve.')