[The cerebral venous outflow tract].

It is generally assumed that the jugular veins are the only significant path for cerebral venous drainage. Little attention has been given to the possible role of other venous paths for the cerebral venous outflow. In fact, the meningorachidian venous plexus acts as the major outflow tract of cerebral circulation in the upright position. This phenomenon is linked with postural variations in cerebrospinal fluid pressure. It is difficult to assess the significance of this posterior venous plexus under physiopathologic conditions, which probably depends on the extent of the anastomoses between the two systems.