Peripheral Nerves Notes PERIPHERAL NERVES n Peripheral nervous

Peripheral Nerves Notes

PERIPHERAL NERVES n Peripheral nervous system is made up of the 31 pairs of spinal nerves plus 12 pairs of cranial nerves n Most are mixed nerves – carrying both sensory and motor information

SPINAL NERVES n Allow brain and body to communicate n Attach to spinal cord by dorsal and ventral roots.

n Posterior/dorsal roots contain sensory fibers whose cell bodies are located in dorsal root ganglion n Anterior/ventral roots contain motor axons and conduct impulses from brain and cord to periphery

CRANIAL NERVES I – Olfactory – sensory nerve that functions in sense of smell II – Optic – arises from retina of the eye and functions in vision III – Oculomotor – mostly motor function – most of muscles of eye, eyelid, and pupillary constriction

n IV – Trochlear – superior oblique muscle of eye n V – Trigeminal – 3 branches – motor- chewing; sensory – skin of face n VI – Abducens –laeral rectus eye muscle abducts the eye

n VII – Facial – motor to muscles of facial expression; sensory – taste n VIII – Vestibulococholear – sensory –hearing and equilibrium (balance) n IX – Glossopharyngeal – motorsecretion of saliva; sensory – taste, regulation of blood pressure, and proprioception of muscles involved in swallowing

n X – Vagus – motor- smooth muscle contraction and relaxation, secretion of digestive fluids; heart, lungs – parasympathetic innervation; sensory from visceral organs it supplies and proprioception

n XI – Accessory – motor: swallowing and movements of head; sensory - proprioception n XII – Hypoglossal – motormovement of tongue during speech and swallowing; sensoryproprioception

COVERINGS n Endoneurium – surrounds individual neuron n Perineurium – surrounds fascicles (bundles of nerve fibers) n Epineurium – surrounds entire nerve