<Li> Mixed nerves contain both afferent and efferent axons, and thus conduct both incoming sensory information and outgoing muscle commands in the same bundle . </Li> <P> Nerves can be categorized into two groups based on where they connect to the central nervous system: </P> <Ul> <Li> Spinal nerves innervate (distribute to / stimulate) much of the body, and connect through the vertebral column to the spinal cord and thus to the central nervous system . They are given letter - number designations according to the vertebra through which they connect to the spinal column . </Li> <Li> Cranial nerves innervate parts of the head, and connect directly to the brain (especially to the brainstem). They are typically assigned Roman numerals from 1 to 12, although cranial nerve zero is sometimes included . In addition, cranial nerves have descriptive names . </Li> </Ul> <Li> Spinal nerves innervate (distribute to / stimulate) much of the body, and connect through the vertebral column to the spinal cord and thus to the central nervous system . They are given letter - number designations according to the vertebra through which they connect to the spinal column . </Li>

A neuron is a muscle cell. nerve cell. fiber cell. cartilage cell