Abstract:

Objective　To perform a microanatomy of the orifice of cerebral bridging veins (BVs) into the superior sagittal sinus (SSS), in order to provide a morphologic basis for the mechanism of cerebral venous thrombosis.　Methods　Thirty cadaveric head specimens were used in this study. The number, location, types and distribution of the orifice were recorded.　Results　A total of 367 outer orifices and 375 inner orifices were found. The outer orifice was the junction outside of the SSS between BV and dural mater. The inner orifice was the sinusal entrance inside of the SSS. For eight cases, two inner orifices drained one of BVs into the SSS with one outer orifice. The orifice mainly located in the anterior or posterior segments of the SSS. Most of outer orifices (70%) directly drained into the SSS, and the others drained into the SSS indirectly by the meningeal veins or parasagittal sinues. A part of outer orifices (37%) drained into the posterior segment of SSS indirectly, in which 85% of them changed the direction of the BVs from against the direction of blood flow in the sinus to along or at a right angle.　Conclusions　This study reveals the complexity of the orifice which commonly changed the direction of the BVs and played an important role for reducing the cerebral venous system thrombosis.

Key words: Superior sagittal sinus, Cerebral bridging vein, Orifice, Microanatomy