Cranial nerve zero

From Wikipedia, the free encyclopedia

The terminal nerve, or cranial nerve zero, was discovered by German scientist Gustav Fritsch in 1878 in the brains of sharks. It was first found in humans in 1913,^[1] although its presence in humans remains controversial. However, studies have indicated that the terminal nerve is a common finding in the adult human brain^[2]. It projects from the nasal cavity, enters the brain just a little bit ahead of the other cranial nerves as a microscopic plexus of unmyelinated peripheral nerve fascicles.

The nerve is often overlooked in autopsies because it is unusually thin for a cranial nerve, and is often torn out upon exposing the brain. Careful dissection is necessary to visualize the nerve. Its purpose and mechanism of function is still open to debate; consequently, nerve 0 is often not mentioned in anatomy textbooks.^[3]

Although very close to (and often confused for a branch of) the olfactory nerve, nerve 0 is not connected to the olfactory bulb, where smells are analyzed. This fact suggests that the nerve is either vestigial or may be related to the sensing of pheromones. This hypothesis is further supported by the fact that nerve zero projects to the medial and lateral septal nuclei, and the preoptic areas, all of which are involved in regulating sexual behavior in mammals.^[4]

The zebrafish has been used as a model in recent research.^[5]

[edit] References

^ R. Douglas Fields, Sex and the Secret Nerve, February/March 2007; Scientific American Mind
^ Fuller GN, Burger PC (1990). "Nervus terminalis (cranial nerve zero) in the adult human". Clin. Neuropathol. 9 (6): 279–83. PMID 2286018.
^ R. Douglas Fields, Sex and the Secret Nerve, February/March 2007; Scientific American Mind
^ R. Douglas Fields, Sex and the Secret Nerve, February/March 2007; Scientific American Mind
^ Whitlock KE (2004). "Development of the nervus terminalis: origin and migration". Microsc. Res. Tech. 65 (1-2): 2–12. doi:10.1002/jemt.20094. PMID 15570589.

[edit] See also

Vomeronasal organ

[edit] External links

n_05/12566897 at Dorland's Medical Dictionary
Diagram at kent.edu ("nervus terminalis", #4)

v • d • e

Nerves of head and neck: the cranial nerves and nuclei

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