Terminal nerve

From Wikipedia, the free encyclopedia
  (Redirected from Cranial nerve zero)
Jump to: navigation, search
Cranial nerve zero
Lawrence 1960 1.3.png
Left The terminal nerve as it is shown on the ventral side of a dog-fish brain. (Topmost label)
Latin nervus terminalis
Code TA A14.2.01.002
Anatomical terminology

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[citation needed] controversial. A 1990 study has indicated that the terminal nerve is a common finding in the adult human brain.[2][3] The nerve has been called by other names, including cranial nerve XIII, Zero Nerve, Nerve N,[4] and NT.[5]

Structure[edit]

The original images (1878) of Fritsch's dogfish shark brain showing the nerve marked by an asterisk.

The terminal nerve appears just anterior of the other cranial nerves bilaterally as a microscopic plexus of unmyelinated peripheral nerve fascicles in the subarachnoid space covering the gyrus rectus. This plexus appears near the cribriform plate and travels posteriorly toward the olfactory trigone, medial olfactory gyrus, and lamina terminalis.[2]

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.[4] 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]

Development[edit]

The zebrafish has been used as a developmental model in recent research.[6]

The connections between the terminal nerve and the olfactory system have been extensively studied in human embryos. It was found to enter the brain at stages 17 and 18 from olfactory origins.}[7]

Function[edit]

Although very close to[8] (and often confused for a branch of) the olfactory nerve, the terminal nerve 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 the terminal nerve projects to the medial and lateral septal nuclei and the preoptic areas, all of which are involved in regulating sexual behavior in mammals.[1]

Additional images[edit]

See also[edit]

References[edit]

  1. ^ a b c Fields, R. Douglas (2007). "Sex and the Secret Nerve". Scientific American Mind 18: 20–7. doi:10.1038/scientificamericanmind0207-20. 
  2. ^ a b Fuller GN, Burger PC (1990). "Nervus terminalis (cranial nerve zero) in the adult human". Clinical Neuropathology 9 (6): 279–83. PMID 2286018. 
  3. ^ Berman L (March 25, 2008). "Scientists discover secret sex nerve". TODAY. 
  4. ^ a b Bordoni B, Zanier E (2013). "Cranial nerves XIII and XIV: nerves in the shadows". Journal of Multidisciplinary Healthcare 6: 87–91. doi:10.2147/JMDH.S39132. PMC 3601045. PMID 23516138. 
  5. ^ Vilensky JA (January 2014). "The neglected cranial nerve: nervus terminalis (cranial nerve N)". Clinical Anatomy 27 (1): 46–53. doi:10.1002/ca.22130. PMID 22836597. 
  6. ^ Whitlock KE (September 2004). "Development of the nervus terminalis: origin and migration". Microscopy Research and Technique 65 (1–2): 2–12. doi:10.1002/jemt.20094. PMID 15570589. 
  7. ^ Müller F, O'Rahilly R (2004). "Olfactory structures in staged human embryos". Cells, Tissues, Organs 178 (2): 93–116. doi:10.1159/000081720. PMID 15604533. 
  8. ^ Von Bartheld CS (September 2004). "The terminal nerve and its relation with extrabulbar "olfactory" projections: lessons from lampreys and lungfishes". Microscopy Research and Technique 65 (1–2): 13–24. doi:10.1002/jemt.20095. PMID 15570592. 

External links[edit]

  • Vilensky JA (January 2014). "The neglected cranial nerve: nervus terminalis (cranial nerve N)". Clinical Anatomy 27 (1): 46–53. doi:10.1002/ca.22130. PMID 22836597. 
  • Fuller GN, Burger PC (1990). "Nervus terminalis (cranial nerve zero) in the adult human". Clinical Neuropathology 9 (6): 279–83. PMID 2286018.