Microanatomy of lamina terminalis cistern

Objective To supply microanatomical data for operations related to lamina terminalis cistern. Methods Lamina terminalis cistern was dissected and measured progressively in 14 cadaver's heads by using an operating microscope. Results Lamina teminalis Cistern was like a tent with high crown. Its upper part was like a gap between bilateral septic areas. The lateral walls inclined laterally and inferiorly. The anterior border was a midline along which two sides of pia mater adhered. The posterior and posterior -inferior wall was lamina terminalis. The bottom was optic chiasma and the arachnoid stretching between optic nerves. The cistern extended anterior -inferiorly to limbus sphenoidalis. It formed a recess between optic nerves in most cases. Both the mean height and length were about 2cm. Anterior cerebral-anterior communicating-artery complex and its fine branches were main contents of the cistern. The fibrous trabeculae were few in most cisterns. Conclusions Fibrous links were few in most lamina terminalis cistern, so it could not be difficult to enter the cistern. But careful and sharp dissection was important between anterior communicating artery and optic nerve/ chiasma. The threadlike things seen behind anterior communicating artery were generally rather perforating branches to hypothalamus than fibrous trabeculae, so they should not be cut rashly. Recurrent artery of Heubner courses anterior, superior or posterior to Al segment of anterior cerebral artery, so separation of these vessels was not difficult in most cases.