Microsurgical anatomy of the structures at stoma of the third ventricle

Objective: To provide anatomic basis for better use of third ventriculostomy to treat obstructive hydrocephalus. Methods: Blood vessles were infused with colored silicone to distinguish arteries and veins in 4 head specimens, while structures at stoma of the third ventricle were observed and messured in other 8 specimens adopting the technique of low temperature sections. Results: The distance from optic chiasm to infundibulum was about(3.5±1.4)mm (2.5～5.3 mm), the distance from the infundibular recess to mamillary body was(8.6±2.3)mm(6.9～11.4 mm), while the infundibular recess and dorsum sellae were in the same ventral level, keeping the dorsum sellae as the major anatomical landmark. Resection of the area which 6.9mm behind the dorsum sellae was feasible. Diencephalic leaf of liliequist membrane constituted the supra-anterior wall of interpeduncular cistern, which had some holes. In interpeduncular cistern, basal artery divided into left and right post cerebral artery P1 branch, separated from dorsal part of P1 and penetrated into brain parenchyma, however no branch separated from ventral part. Conclusions:Protecting hypothalamus and its relevant structures and basal artery could be achieved by selecting the site properly in the floor of the third ventricle, and resection of diencephalic leaf of liliequist membrane can promote CSF circulation.