Drawing of brain in a horizontal section. One can see the choroid plexus (red) which enters the inferior horn of the lateral ventricle with its vessels (mainly the superior choroid vein).The posterior horn of the lateral ventricle is sharply cut.The fornix has been cut through and folded back.Lateral to the choroid plexus the terminal vein runs on each side.Source: Grays Anatomy (1918, Henry Gray)