Notes
Olfactory Cortical Projections (Advanced)
DIAGONAL BAND OF BROCA:
Prominent cholinergic gray and white matter structure.
MEDIAL STRIAE:
Communicate at the anterior commissure.
ANTERIOR PERFORATED SUBSTANCE:
Lies in between the olfactory trigone and the diagonal band of Broca. The perforated appearance of this gross anatomic area gives it its name.
OLFACTORY TUBERCLE:
Gray matter structure that overlies the anterior perforated substance. Innervated by the intermediate olfactory stria.
ANTERIOR OLFACTORY NUCLEUS:
Lies along the anteroposterior length of the olfactory tract. Has cortical cytoarchitecture and, thus, is often referred to as the anterior olfactory cortex.
FLOW FROM OLFACTORY BULB TO PRIMARY OLFACTORY CORTEX:
- The olfactory system bypasses the thalamus, which is unique.
- Impulse passes from the olfactory bulb down the olfactory tract into the lateral olfactory stria to the primary olfactory cortex.
- From the primary olfactory cortex, impulses project to secondary olfactory regions, which include the orbitofrontal cortex, lateral hypothalamus, insula, anterior hippocampus, and indusium griseum.
- Next, impulse passes from the anterior olfactory nucleus down the ipsilateral olfactory tract to the ipsilateral medial stria.
- It decussates in the anterior commissure to the contralateral medial stria and then passes anteriorly along the contralateral olfactory tract to the olfactory bulb.
- Olfactory sensory impulses are bidirectional, which means that the olfactory cortex also communicates with the olfactory bulb in a reciprocal manner.