- Cranial nerve zero
Cranial nerve zero Latin nervus terminalis Code TA A14.2.01.002
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, although its presence in humans remains controversial. However, a study has indicated that the terminal nerve is a common finding in the adult human brain.
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 zero is often not mentioned in anatomy textbooks.
Although very close to (and often confused for a branch of) the olfactory nerve, nerve zero 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.
The connections between cranial nerve zero and the olfactory system has been extensively studied in human embryos. It was found to enter the brain at stages 17 and 18 from olfactory origins.
- ^ a b c 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.
- ^ Von Bartheld CS (September 2004). "The terminal nerve and its relation with extrabulbar "olfactory" projections: lessons from lampreys and lungfishes". Microsc. Res. Tech. 65 (1–2): 13–24. doi:10.1002/jemt.20095. PMID 15570592.
- ^ 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.
- ^ Müller F, O'Rahilly R (2004). "Olfactory structures in staged human embryos". Cells Tissues Organs (Print) 178 (2): 93–116. doi:10.1159/000081720. PMID 15604533.
- Diagram at kent.edu ("nervus terminalis", #4)
Nerves of head and neck: the cranial nerves and nuclei (TA A14.2.01, GA 9.855) olfactory (AON->I) optic (LGN->II) oculomotor
trochlear (TN->IV)no significant branches trigeminal
(PSN, TSN, MN, TMN->V)
abducens (AN->VI)no significant branches facial (FMN, SN, SSN->VII)near origininside
(NA, ISN, SN->IX)before jugular fossaafter jugular fossa
(NA, DNVN, SN->X)before jugular fossaafter jugular fossa
accessory (NA, SAN->XI) hypoglossal (HN->XII)
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