Wikipedia
Occipital sinus
The occipital sinus is the smallest of the cranial sinuses.
It is situated in the attached margin of the falx cerebelli, and is generally single, but occasionally there are two.
It commences around the margin of the foramen magnum by several small venous channels, one of which joins the terminal part of the transverse sinus; it communicates with the posterior internal vertebral venous plexuses and ends in the confluence of the sinuses.
Occipital sinuses were discovered by Guichard Joseph Duverney.