The occipito-hypothalamic interconnection fiber within the fornix: (The first report).

ABSTRACT

Objective: To demonstrate the occipital crus of the fornix from the brain of Thai cadavers and provide here the first finding and the first report. Methods: 10 brains of Thai cadavers, 5 males and 5 females, were bisected. Each half was further dissected to demonstrate the inferior horn, the body and the collateral trigone of the lateral ventricle by removing the cerebrum from the superior part down and backwards. The dissection also removed the body of the corpus collasum and left only the splenium portion. When exposing the inferior horn and the collateral trigone, the hippocampal formation was situated at the inferomedial aspect. We can see the fornix arises from the fimbria of the hippocampus and curves anteriorly to terminate at the mammilary body and the septal nuclei. Another 15 sets of horizontal brain sections and 15 sets of coronal brain sections also helped in confirming this report. The sections passed through the crus of the fornix were selected and observed. Results: We can define and demonstrate another crus of the fornix, which arises from the occipital lobe of the brain, the occipital crus. This crus may arrange in a round elevated bundle or a flat bundle beneath the ependyma and join the posterior part of the hippocampal crus of the fornix at the medial border of the body of the lateral ventricle. Conclusion: The fornix is the fiber which originates from the hippocampal formation to be the fimbria and leaves the hippocampus as the crus part of the fornix. Then it curves superiorly anteriorly and inferiorly to terminate at the septal nuclei and the mammillary body. Another crus of the fornix comes from the occipital cortex posteriorly and joins together with the hippocampal crus to terminate in the same area. This suggests that the occipital crus of the fornix involves in another part of the limbic structures that are responsible for the memory consolidation, emotions and autonomic responses.