Cranial nerve zero | |
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![]() Left The terminal nerve as it is shown on the ventral side of a dog-fish brain. (Topmost label) | |
Details | |
Identifiers | |
Latin | nervus terminalis |
TA98 | A14.2.01.002 |
TA2 | 6179 |
FMA | 76749 |
Anatomical terminology |
Cranial nerves |
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The terminal nerve, also known as cranial nerve 0 or simply as CN 0, is a nerve that was not included in the seminal classification of the cranial nerves as CN I through CN XII but is now generally classified as a cranial nerve. It was discovered by German scientist Gustav Fritsch in 1878 in the brains of sharks. It was first found in humans in 1913.[1] 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 unofficially by other names, including cranial nerve XIII, zero nerve, nerve N,[4] and NT.[5]
The presence of an additional cranial nerve (the nervus terminalis or cranial nerve zero) is well documented in many non-human vertebrate species. However, its existence in the adult human has been disputed. The present study focused on the structure and incidence of this nerve in the adult human brain. The nerve was examined post-mortem in 10 adult brains using dissection microscopy, light microscopy, transmission electron microscopy, and immunohistochemistry. In all specimens, the nervus terminalis was identified bilaterally as a microscopic plexus of unmyelinated peripheral nerve fascicles in the subarachnoid space covering the gyrus rectus of the orbital surface of the frontal lobes. The plexus appeared in the region of the cribriform plate of the ethmoid and coursed posteriorly to the vicinity of the olfactory trigone, medial olfactory gyrus, and lamina terminalis. We conclude that the terminal nerve is a common finding in the adult human brain, confirming early light microscopic reports.