Superior sagittal sinus
The superior sagittal sinus, within the human head, is an unpaired dural venous sinus lying along the attached margin of the falx cerebri. It allows blood to drain from the lateral aspects of the anterior cerebral hemispheres to the confluence of sinuses. Cerebrospinal fluid drains through arachnoid granulations into the superior sagittal sinus and is returned to the venous circulation.
Structure
It is triangular in section. It is narrower anteriorly, and gradually increases in size as it passes posterior-ward.It commences at the foramen cecum, through which it receives emissary veins from the nasal cavity. It passes posterior-ward along its entire course. It is accommodated within a groove which runs across the inner surface of the frontal bone, the adjacent margins of the two parietal lobes, and the superior division of the cruciate eminence of the occipital lobe. Near the internal occipital protuberance, it deviates to either side before draining into the confluence of sinuses, continuing as the corresponding transverse sinus.
The superior sagittal sinus is usually divided into three parts: anterior, middle, posterior.
Its inner surface presents the openings of the superior [cerebral veins], which run, for the most part, obliquely forward, and open chiefly at the back part of the sinus, their orifices being concealed by fibrous folds; numerous fibrous bands extend transversely across the inferior angle of the sinus; and, lastly, small openings communicate with irregularly shaped venous spaces in the dura mater near the sinus.
Venous lacunae
There are usually three lacunae on either side of the sinus: a small frontal, a large parietal, and an occipital, intermediate in size between the other two.Most of the cerebral veins from the outer surface of the hemisphere open into these lacunæ, and numerous arachnoid granulations project into them from below.