Terminal nerve

The accepted name of terminal nerve is due to its entrance in the lamina terminalis regions. The nerve has previously been called nerve of Pinkus, tractus olfacto-commissuralis, nervus terminalis, cranial nerve XIII, zero nerve, nerve N, and NT.

Structure

The terminal nerve appears just in front of the other cranial nerves (rostral to all other cranial nerves, located on the ventral surface of the human brain) and would, if earlier recognized, have been classified as cranial nerve one. It first appears bilaterally as a microscopic plexus of unmyelinated peripheral nerve fibers in the subarachnoid space covering the straight gyrus. The plexus appears near the cribriform plate and travels posteriorly toward the olfactory trigone and lamina terminalis.

The terminal nerve is clearly seen in the human embryo but loses some of its ganglion cells before birth making it less recognizable in adults. The nerve is therefore often overlooked in autopsies, and is often torn out upon exposing the brain. Careful dissection is necessary to visualize the nerve.

Development

The zebrafish was used as a developmental model in research from 2004.

The connections between the terminal nerve and the olfactory system have been extensively studied in human embryos. Olfactory nerve fibers enter the brain at stage 17, fibers from the vomeronasal organ and fibers of the terminal nerve enter the brain at stages 17 and 18. During prenatal development some of the ganglion cells are lost.