Chapter 14 - The Brain and Cranial Nerves - Checkpoint - Page 502: 25

Functions of the Cranial Nerves CN I . Olfactory. The olfactory nerve conducts impulses for the sense of smell. CN II. Optic Nerve . Conducts impulses for the sense of sight (vision).. CN III. Oculomotor Nerve. Controls muscles that move the eyeballs and eyelids CN IV. Trochlear Nerve. Controls muscle of eyeball movements. CN V, Trigeminal Nerve. Ophthalmic branch, conducts sensory impulses from skin of upper eyelid, cornea, tear glands, upper nasal cavity, side of head nose forehead and anterior half of scalp. Mandibular branch : conducts stimuli from anterior 2/3rds of tongue, from cheek, mucosa, lower teeth, skin over mandible, side of head, anterior to ear, and mucosa of floor of mouth. It also innervates muscles concerned with mastication and swallowing. The maxillary branch is sensory; it innervates lower eyelids, and conjunctiva, lacrimal glands, inferior nasal cavity, cheeks, upper lip, upper teeth and gingiva, and upper palate. CN VI. Abducens Nerve. Purely somatic afferent. Responsible for control of rectus muscle which abducts the eyeball ipsilaterally. CN VII Facial Nerve Mixed cranial nerve. Responsible for contraction of muscles of facial expression.; also transmits taste from anterior 2/3rds of the tongue. Conducts sensations from middle ear, and innervates sublingual salivary glands, nasal mucosa, and lacrimal glands. CN VIII Vestibulocochlear : Vestibular branch conducts balance sensations. The cochlear branch conducts auditory stimuli. CN IX. Glossopharyngeal nerve:This nerve conducts taste sensations from the posterior 1/3rd of the tongue. It also transmits parasympathetic signals to the parotid gland, and otic ganglion. CN X. Vagus Nerve. This is a mixed nerve. It is the longest cranial nerve.--it traverses through neck, and thorac to the position of the splenic flexure of the colon in the abdomen. The vagus conducts taste sensations from the root of tongue and epiglottis, It also modulates swallowing and sound production. Most of the muscles of the pharynx and larynx are served by the vagus.. In addition, parasympathetic fibers from the vagus modulate heart rate and rhythm, stimulate smooth muscle contraction in the digestive tract, and promote gastric emptying and glandular secretion. CN XI. Accessory; This comprises both a cranial accessory branch and a spinal accessory branch. The sensory axons end in the medulla; the motor axons descend to the spinal cord. The cranial branch coordinates head movements; the spinal branch controls movements --elevation and depression-- of the shoulders. CN XII Hypoglossal Nerve. Neurons of this nerve originate in the hypoglossal nucleus of the medulla. It helps. to regulate the functions of speech, and swallowing.

The trigeminal nerve has sensory fibers that conduct stimuli for pain , pressure, thermal sensations, and proprioception