Cranial nerve zero

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,[1] 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.[2]

Contents

Anatomy

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 zero is often not mentioned in anatomy textbooks.[1]

Function

Although very close to[3] (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.[1]

Development

The zebrafish has been used as a developmental model in recent research.[4]

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.[5]

See also

References

  1. ^ a b c R. Douglas Fields, Sex and the Secret Nerve, February/March 2007; Scientific American Mind
  2. ^ Fuller GN, Burger PC (1990). "Nervus terminalis (cranial nerve zero) in the adult human". Clin. Neuropathol. 9 (6): 279–83. PMID 2286018. 
  3. ^ 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. 
  4. ^ 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. 
  5. ^ 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. 

External links

  • Diagram at kent.edu ("nervus terminalis", #4)
v · d · eNerves of head and neck: the cranial nerves and nuclei (TA A14.2.01, GA 9.855)
olfactory (AON->I)
optic (LGN->II)
oculomotor
(ON, EWN->III)
trochlear (TN->IV)
no significant branches
trigeminal
(PSN, TSN, MN, TMN->V)
abducens (AN->VI)
no significant branches
facial (FMN, SN, SSN->VII)
near origin
vestibulocochlear
(VN, CN->VIII)
glossopharyngeal
(NA, ISN, SN->IX)
ganglia (superior, inferior)
vagus
(NA, DNVN, SN->X)
ganglia (superior, inferior)
accessory (NA, SAN->XI)
hypoglossal (HN->XII)

M: PNS

anat(h/r/t/c/b/l/s/a)/phys(r)/devp/prot/nttr/nttm/ntrp

noco/auto/cong/tumr, sysi/epon, injr

proc, drug(N1B)



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