Cranial Nerves

Cranial Nerves | Type | Origins | Destination | Functions | Clinical Testing |

Olfactory nerve I | Purely Sensory | Olfactory mucosa in nasal cavity | Olfactory bulbs | Transmits the sense of smell. | In order to test the olfactory nerve, the physician has the patient hold a nostril shot, close the eyes and let the doctor know when he smells a test odor. Repeated for other side. |

Optic nerve II | Purely Sensory | Retina of the eye | Thalamus of the midbrain | Transmits visual information to the brain. | Is tested through techniques similar to those an eye doctor uses to evaluate visual acuity. |

Oculomotor nerve III | Mainly Motor | Midbrain | Somatic motor: superior, inferior, and medial rectus muscles, intrinsic eye muscles | Moves the eyeball. Also carry autonomic (parasympathetic) nerve fibers that constrict the pupil. | The oculomotor nerve is tested by observing pupil dilation in response to changes in light. |

Trochlear nerve IV | Mainly Motor | Midbrain | Superior oblique muscle of the eye | Turns the eyeball downwards and outwards. | Tested by evaluating the patient's ability to visually track a moving object. |

Trigeminal nerve V | Mixed | Ophthalmic branch (sensory); orbital structures, nasal cavity, skin of forehead, superior eyelid, eyebrow, and part of the nose | Ophthalmic, maxillary and mandibular branches to sensory nuclei in the pons | Receives sensation from the face and innervates the muscles of mastication. | This nerve is tested by evaluating the patient's ability to sense touch over the forehead, cheek and jaw, as well as her ability to move and clench the jaw. |

Abducens nerve VI | Mainly motor | Inferior Pons | lateral rectus muscle of the eye | Moves the eyeball outwards. | Tested by evaluating the patient's ability to visually track a moving object. |

Facial Nerve VII | Mixed | Sensory from taste receptors on anterior two-thirds of the tongue; motor from motor nuclei of pons | Sensory to sensory nuclei of pons Somatic...