12. Venous phase of internal carotid arteriogram, AP projection
The right transverse sinus begins at the confluence of sinuses as a
continuation of the superior sagittal sinus. The left transverse sinus
begins in the same place as a continuation of the straight sinus. Each transverse
sinus lies in the lateral, attached margin of the tentorium cerebelli, and drains
directly into the adjacent sigmoid sinus. Each sigmoid sinus curves downward
behind the mastoid antrum, grooving the internal surface of the temporal bone.
The sigmoid sinuses leave the skull via the jugular foramina to become the internal
jugular veins.
