Does it Really Exist? Cranial Nerve Zero aka the Terminal Nerve

I was first introduced to the terminal nerve on Dr. Rob Sinnott’s page on Facebook.

I looked into it a little bit and was fairly fascinated by what was, to me, a completely new concept.

Seeing as how I am constantly reminding you that chiropractic is all about removing nervous system interference, I thought mentioning this here would be appropriate.

Here is a summary from Wikipedia:

“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. 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.

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 zebrafish has been used as a model in recent research.”

Here is some more info I found on the elusive terminal nerve:

“Any of the plexiform nerve strands passing parallel and medial to the olfactory tracts, distributing with the olfactory nerves and passing centrally into the anterior perforated substance.” – The American Heritage Medical Dictionary

“A small nerve originating in the vomeronasal epithelium, projecting to the cerebral hemisphere in the region of the olfactory trigone. It is classified by most anatomists as part of the olfactory, or first cranial, nerve. It courses anteriorly along the olfactory tract and passes through the ethmoid bone. It communicates in the nasal cavity with the ophthalmic division of the trigeminal nerve.” – Mosby’s Medical Dictionary, 8th edition

So if the terminal nerve aka cranial nerve zero has been known since 1913, why didn’t we learn about it in chiropractic school? I’m not sure.

Maybe this is further evidence that chiropractic students really are learning 1895 chiropractic in 2009 chiropractic schools.

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