Structure and Visibility - The terminal nerve is a microscopic plexus of unmyelinated peripheral nerve fascicles. - It appears near the cribriform plate and travels posteriorly toward the olfactory trigone, medial olfactory gyrus, and lamina terminalis. - The nerve is often overlooked in autopsies due to its thinness and is often torn out when exposing the brain. - Careful dissection is necessary to visualize the nerve. - The nerve is not commonly mentioned in anatomy textbooks.

Development - The zebrafish has been used as a developmental model in studying the terminal nerve. - The connections between the terminal nerve and the olfactory system have been extensively studied in human embryos. - The nerve enters the brain at stages 17 and 18 from olfactory origins.

Function - The terminal nerve is not connected to the olfactory bulb, suggesting it may be vestigial or involved in sensing pheromones. - It projects to the medial and lateral septal nuclei and the preoptic areas, which are involved in regulating sexual behavior in mammals. - A study in hamsters found that mating is reduced when the terminal nerve is severed.

Additional Images - Three forms of the nerve can be observed on the underside of human brains. - The gyrus rectus can be seen at the anterior center when viewing the brain from below.

Related Topic - Vomeronasal organ