Nerve: Cranial nerves
Inferior view of the brain and brain stem showing cranial nerves. An unlabelled version is here
Latin	nervus cranialis

Cranial nerves are nerves that emerge directly from the brain stem in contrast to spinal nerves which emerge from segments of the spinal cord.

Contents 1 Origin and function 2 Cranial nerves in non-human vertebrates 3 List of cranial nerves 4 Mnemonic devices 5 See also 6 References

[edit] Origin and function

Although thirteen cranial nerves in humans fit this description, twelve are conventionally recognized. The nerves from the third onward arise from the brain stem.

Except for the tenth and the eleventh nerve, they primarily serve the motor and sensory systems of the head and neck region. However, unlike peripheral nerves which are separated to achieve segmental innervation, cranial nerves are divided to serve one or a few specific functions in wider anatomical territories.^{[citation needed]}

[edit] Cranial nerves in non-human vertebrates

Human cranial nerves are evolutionarily homologous to those found in many other vertebrates. Cranial nerves XI and XII evolved in the common ancestor to amniotes (non-amphibian tetrapods) thus totaling twelve pairs. These characters are synapomorphies for their respective clades. In some primitive cartilaginous fishes, such as the dogfish (Squalus acanthias), there is a terminal nerve numbered zero (as it exits the brain before the first cranial nerve).

[edit] List of cranial nerves

#	Name	Sensory, Motor or Both	Origin	Nuclei	Function
0	Cranial nerve zero (CN0 is not traditionally recognized.)[1]	Sensory		olfactory trigone, medial olfactory gyrus, and lamina terminalis	Still controversial New research indicates CN0 may play a role in the detection of pheromones [2][3]
I	Olfactory nerve	Purely Sensory		Anterior olfactory nucleus	Transmits the sense of smell; Located in olfactory foramina of ethmoid
II	Optic nerve	Purely Sensory		Lateral geniculate nucleus	Transmits visual information to the brain; Located in optic canal
III	Oculomotor nerve	Mainly Motor	Midbrain	Oculomotor nucleus, Edinger-Westphal nucleus	Innervates levator palpebrae superioris, superior rectus, medial rectus, inferior rectus, and inferior oblique, which collectively perform most eye movements; Located in superior orbital fissure
IV	Trochlear nerve	Mainly Motor	Midbrain	Trochlear nucleus	Innervates the superior oblique muscle, which depresses, rotates laterally (around the optic axis), and intorts the eyeball; Located in superior orbital fissure
V	Trigeminal nerve	Both Sensory and Motor	Pons	Principal sensory trigeminal nucleus, Spinal trigeminal nucleus, Mesencephalic trigeminal nucleus, Trigeminal motor nucleus	Receives sensation from the face and innervates the muscles of mastication; Located in superior orbital fissure (ophthalmic nerve - V1), foramen rotundum (maxillary nerve - V2), and foramen ovale (mandibular nerve - V3)
VI	Abducens nerve	Mainly Motor	Posterior margin of Pons	Abducens nucleus	Innervates the lateral rectus, which abducts the eye; Located in superior orbital fissure
VII	Facial nerve	Both Sensory and Motor	Pons (cerebellopontine angle) above olive	Facial nucleus, Solitary nucleus, Superior salivary nucleus	Provides motor innervation to the muscles of facial expression and stapedius, receives the special sense of taste from the anterior 2/3 of the tongue, and provides secretomotor innervation to the salivary glands (except parotid) and the lacrimal gland; Located and runs through internal acoustic canal to facial canal and exits at stylomastoid foramen
VIII	Vestibulocochlear nerve (or auditory-vestibular nerve or statoacoustic nerve)	Mostly sensory	Lateral to CN VII (cerebellopontine angle)	Vestibular nuclei, Cochlear nuclei	Senses sound, rotation and gravity (essential for balance & movement). More specifically. the vestibular branch carries impulses for equilibrium and the cochlear branch carries impulses for hearing.; Located in internal acoustic canal
IX	Glossopharyngeal nerve	Both Sensory and Motor	Medulla	Nucleus ambiguus, Inferior salivary nucleus, Solitary nucleus	Receives taste from the posterior 1/3 of the tongue, provides secretomotor innervation to the parotid gland, and provides motor innervation to the stylopharyngeus (essential for tactile, pain, and thermal sensation)[citation needed]. Some sensation is also relayed to the brain from the palatine tonsils. Sensation is relayed to opposite thalamus and some hypothalamic nuclei. Located in jugular foramen
X	Vagus nerve	Both Sensory and Motor	Posterolateral sulcus of Medulla	Nucleus ambiguus, Dorsal motor vagal nucleus, Solitary nucleus	Supplies branchiomotor innervation to most laryngeal and all pharyngeal muscles (except the stylopharyngeus, which is innervated by the glossopharyngeal); provides parasympathetic fibers to nearly all thoracic and abdominal viscera down to the splenic flexure; and receives the special sense of taste from the epiglottis. A major function: controls muscles for voice and resonance and the soft palate. Symptoms of damage: dysphagia (swallowing problems). Located in jugular foramen
XI	Accessory nerve (or cranial accessory nerve or spinal accessory nerve)	Mainly Motor	Cranial and Spinal Roots	Nucleus ambiguus, Spinal accessory nucleus	Controls muscles of the neck and trapezeus, overlaps with functions of the vagus. Examples of symptoms of damage: inability to shrug, weak head movement, velopharyngeal insufficiency; Located in jugular foramen
XII	Hypoglossal nerve	Mainly Motor	Medulla	Hypoglossal nucleus	Provides motor innervation to the muscles of the tongue (except for the palatoglossus, which is innervated by the vagus) and other glossal muscles. Important for swallowing (bolus formation) and speech articulation. Located in hypoglossal canal

[edit] Mnemonic devices

As the list is important to keep in mind during the examination of the nervous system, there are many mnemonic devices in circulation to help remember the names and order of the cranial nerves. Because the mind recalls rhymes well, the best mnemonics often use rhyming schemes. Three of the best known examples are,"Oh, Oh, Oh To Take A Family Vacation! Go Vegas After Hours!", or "On old Olympus' Towering Tops, a Finn and German viewed and hopped" and "Oh Oh Oh To Touch And Feel a Virgin Girl's Vagina And Hymen" ^[4].

[edit] See also

• Cranial nerve nucleus
• List of mnemonics for the cranial nerves

Old Opie Occassionally Tries Trigonometry And Feels Very Gloomy, Vague, And Hypoactive (taken from the second edition of Human Anatomy by Kenneth S. Saldin 2008).

[edit] References

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (January 2008)

v • d • e Nervous system (TA A14, GA 9) Central nervous system Meninges Spinal cord Brain: Rhombencephalon (Medulla oblongata, Pons, Cerebellum) • Mesencephalon • Prosencephalon (Diencephalon, Telencephalon) Peripheral nervous system Somatic Sensory nerve • Motor nerve • Cranial nerves • Spinal nerves Autonomic Sympathetic • Parasympathetic • Enteric nervous system central nervous system navs: anat/physio/dev, noncongen/congen/neoplasia, symptoms+signs/eponymous, proc peripheral nervous system navs: anat/histo/physio/dev, noncongen PNS somatic/autonomic/congen/neoplasia, symptoms+signs/eponymous, proc

v • d • e Nerves of head and neck: the cranial nerves and nuclei (TA A14.2.01, GA 9.855) olfactory (AON->I) olfactory bulb · olfactory tract optic (LGN->II) optic chiasm · optic tract oculomotor (ON, EWN->III) superior branch (parasympathetic root of ciliary ganglion/ciliary ganglion) · inferior branch trochlear (TN->IV) no significant branches trigeminal (PSN,TSN,MN,TMN->V) trigeminal ganglion • ophthalmic • maxillary • mandibular abducens (AN->VI) no significant branches facial (FMN,SN,SSN->VII) near origin nervus intermedius • geniculate inside facial canal greater petrosal (pterygopalatine ganglion) · nerve to the stapedius · chorda tympani (lingual nerve, submandibular ganglion) at stylomastoid foramen posterior auricular · suprahyoid (digastric, stylohyoid) · parotid plexus (temporal, zygomatic, buccal, mandibular, cervical) vestibulocochlear (VN, CN->VIII) cochlear (striae medullares, lateral lemniscus) • vestibular (Scarpa's ganglion) glossopharyngeal (NA, ISN, SN->IX) before jugular fossa ganglia (superior, inferior) after jugular fossa tympanic (tympanic plexus, lesser petrosal, otic ganglion) • stylopharyngeal branch • pharyngeal branches • tonsillar branches • lingual branches • carotid sinus vagus (NA, DNVN, SN->X) before jugular fossa ganglia (superior, inferior) after jugular fossa meningeal branch · auricular branch neck pharyngeal branch (pharyngeal plexus) · superior laryngeal (external, internal) · recurrent laryngeal (inferior) · superior cervical cardiac thorax inferior cardiac · pulmonary · vagal trunks (anterior, posterior) abdomen celiac · renal · hepatic · anterior gastric · posterior gastric accessory (NA,SAN->XI) cranial · spinal hypoglossal (HN->XII) lingual branches