What are the 12 cranial nerves Functions and diagram Health ConditionsHealth ConditionsAlzheimer's & DementiaAnxietyArthritisAsthma & AllergiesBreast CancerCancerCardiovascular HealthCOVID-19Dermatology & SkincareDiabetesEnvironment & SustainabilityExercise & FitnessEye HealthHeadache & MigraineHealth EquityHIV & AIDSHuman BiologyInflammatory Bowel DiseaseLeukemiaLGBTQIA+Men's HealthMental HealthMultiple Sclerosis (MS)NutritionParkinson's DiseasePsoriasisSexual HealthWomen's HealthDiscoverNewsLatest NewsOriginal SeriesMedical MythsHonest NutritionThrough My EyesNew Normal HealthPodcastsHow to understand chronic painWhat is behind vaccine hesitancy?The amazing story of hepatitis C, from discovery to cureNew directions in dementia researchCan psychedelics rewire a depressed, anxious brain?Why climate change matters for human healthToolsGeneral HealthDrugs A-ZHealth HubsHealth ToolsBMI Calculators and ChartsBlood Pressure Chart: Ranges and GuideBreast Cancer: Self-Examination GuideSleep CalculatorHealth ProductsAffordable Therapy OptionsBlood Pressure MonitorsDiabetic SuppliesFitness TrackersHome GymsGreen Cleaning ProductsHow to Shop for CBDQuizzesRA Myths vs FactsType 2 Diabetes: Managing Blood SugarAnkylosing Spondylitis Pain: Fact or FictionConnectAbout Medical News TodayWho We AreOur Editorial ProcessContent IntegrityConscious LanguageNewslettersSign UpFollow UsMedical News TodayHealth ConditionsDiscoverToolsConnectSubscribe What are the 12 cranial nerves Medically reviewed by Heidi Moawad, M.D. — By Shannon Johnson — Updated on June 5, 2022The cranial nerves are a set of twelve nerves that originate in the brain. Each has a different function responsible for sense or movement. Share on PinterestIbai Acevedo/StocksyThe functions of the cranial nerves are sensory, motor, or both. Sensory cranial nerves help a person see, smell, and hear. Conversely, motor cranial nerves help control muscle movements in the head and neck.Each nerve has a name that reflects its function and a number according to its location in the brain. Scientists use Roman numerals from I to XII to label the cranial nerves in the brain. The 12 cranial nerves include the:olfactory nerveoptic nerveoculomotor nervetrochlear nervetrigeminal nerveabducens nervefacial nervevestibulocochlear nerveglossopharyngeal nervevagus nerveaccessory nervehypoglossal nerve This article will explore the functions of each of the cranial nerves and provide a diagram. I Olfactory nerve The olfactory nerve transmits information regarding a person’s sense of smell to the brain. When an individual inhales fragrant molecules, olfactory receptors within the nasal passage send the impulses to the cranial cavity, which then travel to the olfactory bulb. Specialized olfactory neurons and nerve fibers meet with other nerves, which pass into the olfactory tract. The olfactory tract then travels to the frontal lobe and other areas of the brain that have a role in memory and the notation of different smells. II Optic nerve The optic nerve transmits information to the brain regarding a person’s vision. When light enters the eye, it hits the retina, which contains rods and cones. These are photoreceptors that translate signals from light into visual information for the brain. These cones sit within the central retina and have a role in color vision. Conversely, the rods in the peripheral retina are responsible for noncolor vision. The photoreceptors carry signal impulses along nerve cells to form the optic nerve. Most of the fibers of the optic nerve cross into a structure called the optic chiasm. The optic tract then projects to the primary visual cortex in the occipital lobe at the back of the brain. The occipital lobe is where the brain handles visual information. III Oculomotor nerve The oculomotor nerve helps control muscle movements of the eyes. The oculomotor nerve provides movement to most of the muscles that move the eyeball and upper eyelid, known as extraocular muscles. The oculomotor nerve also helps with involuntary functions of the eye. For example, the sphincter pupillae muscle automatically constricts the pupil to allow less light into the eye in bright light conditions. When it is dark, the muscle relaxes to allow more light to enter. Another function is when the ciliary muscles help the lens adjust to short-range and long-range vision. This happens automatically when a person looks at near or far objects. IV Trochlear nerve The trochlear nerve also has a role in eye movement. The trochlear nerve, like the oculomotor nerve, originates in the midbrain. It powers the contralateral superior oblique muscle that allows the eye to point downward and inward. V Trigeminal nerve The trigeminal nerve is the largest cranial nerve and has both motor and sensory functions. Its motor functions help a person to chew and clench the teeth. It also gives sensation to muscles in the tympanic membrane of the ear. Its sensory division has three parts that connect to sensory receptor sites on the face:The ophthalmic part gives sensation to parts of the eyes, including the cornea, mucosa in the nose, and skin on the nose, the eyelid, and the forehead.The maxillary part gives sensation to the middle third of the face, side of the nose, upper teeth, and lower eyelid.The mandibular part gives sensation to the lower third of the face, the tongue, mucosa in the mouth, and lower teeth. Trigeminal neuralgia is a common disorder of the trigeminal nerve that can cause intense pain and facial tics. VI Abducens nerve The abducens nerve also helps control eye movements. It helps the lateral rectus muscle, one of the extraocular muscles, turn the gaze outward. The abducens nerve starts in the pons of the brainstem, enters an area called Dorello’s canal, travels through the cavernous sinus, and ends at the lateral rectus muscle within the bony orbit. VII Facial nerve The facial nerve also has both motor and sensory functions. The facial nerve is consists of four nuclei that serve different functions:movement of muscles that produce facial expressionmovement of the lacrimal, submaxillary, and submandibular glandsthe sensation of the external earthe sensation of taste The four nuclei originate in the pons and medulla and join together to travel to the geniculate ganglion. Bell’s palsy is a common disorder of the facial nerve, which causes paralysis on one side of the face and possibly loss of taste sensation. VIII Vestibulocochlear nerve The vestibulocochlear nerve helps with a person’s hearing and balance. This nerve contains two components: the vestibular nerve and the cochlear nerve. The vestibular nerve helps the body sense changes in the position of the head with regard to gravity. The body uses this information to maintain balance. The cochlear nerve helps with hearing. Specialized inner hair cells and the basilar membrane vibrate in response to sounds and determine the frequency and magnitude of the sound. These fibers combine in the pons and exit the skull via the internal acoustic meatus in the temporal bone. IX Glossopharyngeal nerve The glossopharyngeal nerve possesses both motor and sensory functions. The sensory function receives information from the throat, tonsils, middle ear, and back of the tongue. It also has a role in the sensation of taste on the back of the tongue. The motor division provides movement to the stylopharyngeus, a muscle that allows the throat to shorten and widen. The glossopharyngeal nerve starts in the medulla oblongata in the brain and leaves the skull through the jugular foramen, which leads to the tympanic nerve. X Vagus nerve The vagus nerve has a range of functions, providing motor, sensory, and parasympathetic functions.The sensory part provides sensation to the outer part of the ear, throat, heart, and abdominal organs. It also plays a role in taste sensation.The motor part provides movement to the throat and soft palate.The parasympathetic function regulates heart rhythm and innervates the smooth muscles in the airway, lungs, and gastrointestinal tract. Doctors use vagus nerve stimulation therapy to treat various conditions, including epilepsy, depression, and anxiety. Learn more about the vagus nerve and stimulation therapy. XI Accessory nerve The accessory nerve provides motor function to some muscles in the neck. It controls the sternocleidomastoid and trapezius muscles that allow a person to rotate, extend, and flex the neck and shoulders. The accessory nerve separates into spinal and cranial parts. The spinal component starts in the spinal cord and travels into the skull through the foramen magnum. From there, it meets the cranial component of the accessory nerve and exits the skull along the internal carotid artery. The cranial part of the accessory nerve combines with the vagus nerve. XII Hypoglossal nerve The hypoglossal nerve is a motor nerve that supplies the tongue muscles. It originates in the medulla. Disorders of the hypoglossal nerve can cause paralysis of the tongue, most often occurring on one side. Diagram of cranial nerves The following diagram illustrates the different ways cranial nerves impact the brain:Share on Pinterest Summary The twelve cranial nerves are a group of nerves that start in the brain and provide motor and sensory functions to the head and neck. Each cranial nerve has unique anatomical characteristics and functions. Doctors can identify neurological or psychiatric disorders by testing cranial nerve functions. Frequently asked questions Here are some common questions and answers about the 12 cranial nerves. How do I remember the 12 cranial nerves There are many mnemonics a person can use to remember the 12 cranial nerves. One example is: “Oh Oh Oh To Touch And Feel Very Good Velvet — Ah, Heaven!” Which cranial nerve is largest The vagus nerve is the longest cranial nerve as it starts in the medulla — the bottom part of the brain — and extends to the abdomen. Which is the shortest nerve The shortest cranial nerve is the trochlear nerve, as it has the lowest number of axons. Last medically reviewed on May 30, 2022Neurology / NeurosciencePsychology / Psychiatry 9 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Bordoni, B., et al. (2021). Neuroanatomy, cranial nerve 8 (vestibulocochlear).https://www.ncbi.nlm.nih.gov/books/NBK537359/Bordoni, B., et al. (2021). Neuroanatomy, cranial nerve 11 (accessory).https://www.ncbi.nlm.nih.gov/books/NBK507722/Crowther, G. (n.d.). Cranial nerve functions.https://faculty.washington.edu/crowther/Misc/Songs/cranial.shtmlHelwany, M., et al. (2021). Neuroanatomy, cranial nerve 1 (olfactory).https://www.ncbi.nlm.nih.gov/books/NBK556051/Kenny, B. J., et al. (2021). Neuroanatomy, cranial nerve 10 (vagus nerve).https://www.ncbi.nlm.nih.gov/books/NBK537171/Kim, S. Y., et al. (2021). Neuroanatomy, cranial nerve 12 (hypoglossal).https://www.ncbi.nlm.nih.gov/books/NBK532869/Nguyen, J. D., et al. (2021). Anatomy, head and neck, eye nerves.https://www.ncbi.nlm.nih.gov/books/NBK549919/Smith, A. M., et al. (2021). Neuroanatomy, cranial nerve 2 (optic).https://www.ncbi.nlm.nih.gov/books/NBK507907/Thomas, K., et al. (2022). Neuroanatomy, cranial nerve 9 (glossopharyngeal).https://www.ncbi.nlm.nih.gov/books/NBK539877FEEDBACK:Medically reviewed by Heidi Moawad, M.D. — By Shannon Johnson — Updated on June 5, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related CoverageTrigeminal neuralgia treatment, symptoms, and causesMedically reviewed by Nancy Hammond, M.D. Trigeminal neuralgia is a rare nerve disorder that causes sudden, sharp attacks of pain in the face. Learn about its causes and treatment.READ MORENerve conduction velocity: Side effects and normal valuesMedically reviewed by Seunggu Han, MD A nerve conduction velocity test measures how fast the nerves in the body send important signals. If they are too slow, this may indicate nerve damage…READ MOREWhat to know about Bell's palsyMedically reviewed by Seunggu Han, MD Bell's palsy causes muscle weakness or paralysis on one side of the face. Learn about causes, risk factors, and treatment options.READ MORERadial nerve injury: Everything you need to knowMedically reviewed by Nancy Hammond, MD The radial nerve is prone to injury, even from minor incidents, such as sleeping on the arm. Radial nerve injury is also common after breaking the arm.READ MOREWhat to know about epilepsyMedically reviewed by Heidi Moawad, MD Epilepsy is a fairly common neurological condition characterized by recurrent seizures. In this article, learn about the different types of epilepsy…READ MORE