Olfactory trigone

The olfactory trigone is a small triangular region at the posterior end of the olfactory tract. It is formed where the fibres of the olfactory tract spread out and continue into the different olfactory striae.

It lies on the inferior surface of the frontal lobe, immediately anterior to the anterior perforated substance, whose anterior boundary it helps define. The olfactory tubercle is closely related but should not be confused with the olfactory trigone; the former refers to a prominence in the anterior part of the anterior perforated substance.

Functionally, the olfactory trigone can be best understood as a transition and branching point in the olfactory pathway, rather than as a major processing centre. Processed olfactory information reaches it through the olfactory tract and is then distributed through the olfactory striae toward different olfactory regions of the forebrain.

Simple pathway: Olfactory bulb → olfactory tract → olfactory trigone → olfactory striae → olfactory cortical regions.