Venous blood from the brain enters the cerebral veins which converge on a series of sinuses that feed into the internal jugular vein.
The main veins on the surface of the brain are shown opposite.
The main venous sinus is the superior sagittal sinus which carries blood in the midline of the skull backwards towards the transvers and sigmoid sinuses which feed into the internal jugular vein.
Cavernous Sinus Thrombosis
Veins from the eye and face drain into the cavernous sinus and then into the internal jugular vein. It should be noted that the cavernous sinus, because of its anatomical relationships to major nerves and other structures, can cause major disability if it becomes thrombosed.
In patients with cavernous sinus thrombosis, headaches often start within five to 10 days of developing an infection in the face or skull. Normally this infection would be treated with antibiotics, but if not other sympatoms develop. These include swelling, bulging and redness of the eyes, eye pain, double or blurred vision, and difficulty moving the eyes and the eyelids. Unless treated,patients with cavernous sinus thrombosis become increasingly drowsy and eventually fall into a coma.
The cavernous sinus is close to, but outside the pituitary fossa, and has relationships to the internal carotid artery and some major nerves innervating the eye and face.
The diagram shows the major veins within the skull, which drain into the internal jugular vein.
These larger veins taking blood from the brain and skull are protected the strong fibrous membranes such as the falx cerebri and the tentorium.
The superior sagittal sinus occurs at the top edge of a fibrous membrane that separates the two cerebral hemispheres, called the falx cerebri, which is continuous with the dura mater. Cerebral veins cross the subarachnoid space to enter the sinus.