Flattened sheet-like fornix forming a "Cobra Hood" deformity: A previously unreported variant of fornix anatomy and its implication for surgical approaches to the third ventricle.
BACKGROUND
The fornix is the main efferent tract from the hippocampus and is an important component of the memory pathways. Variations in the anatomy of the fornix are not commonly encountered.


METHODS
The anatomy of the fornix was studied in 30 cadavers of normal adult healthy males who had died in road accidents. The full extent of the hippocampus was prosected up to the tail under the magnoscope.


RESULTS
In 10 of the 30 brains, the crura and the body of fornix were bilaterally broad and flat like a sheet, rather than the usual compact bundle, forming a cobra-like hood over the roof of the third ventricle. The maximum width was approximately 16 mm on the right side (mean: 11.7 mm) and 11 mm on the left (mean: 8.5mm).


CONCLUSIONS
Knowledge of this variation will be useful during the transcallosal approach to third ventricle tumors, especially while going subchoroidal, because an unexpected lateral span of the fornix in the surgical corridor can result in inadvertent injury to it, leading to memory defects.
Department of Anatomy, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Tulika
T
Gupta
Department of Anatomy, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Daisy
D
Sahni
Seattle Science Foundation, Seattle, Washington, USA.
R Shane
RS
Tubbs
Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Sunil K
SK
Gupta
D000328:Adult; D002102:Cadaver; D002552:Cerebral Ventricles / Q000473:pathology* / Q000601:surgery; D020712:Fornix, Brain / Q000002:abnormalities* / Q000601:surgery; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008297:Male; D019635:Neurosurgical Procedures; D020542:Third Ventricle / Q000473:pathology / Q000601:surgery*