Dictionary.net

These are two in number. 1. SUPERIOR LONGITUDINAL SINUS, S. falsifor’mis superior seu triangula'ris. Sinus median, (Ch.) A long, triangular canal; convex above, concave below; which occupies the whole of the upper edge of the falx cerebri. It is broad behind, and much narrower before, where it commences by a cul-de-sac, at the crista galli of the ethmoid bone. It passes along the frontal or coronal crest, sagittal suture, and the vertical groove of the occipital bone. It receives several veins from the dura mater; and all those that are spread over the convex and plain surfaces of the two hemispheres of the brain. It discharges itself into the upper part of the torcular Herophili. 2. INFERIOR LONGITUDINAL SINUS, S. falcifor'mis inferior, Vena falcis cer'ebri. This is much narrower than the last, and occupies the inferior edge of the falx cerebri, from its anterior third to the tentorium cerebelli, where it terminates, commonly by two branches, in the straight sinus.