Cerebrospinal fluid drains through arachnoid granulations into the superior sagittal sinus and is returned to the venous circulation.

[3] 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 (chordae Willisii) extend transversely across the inferior angle of the sinus; and, lastly, small openings communicate with irregularly shaped venous spaces (venous lacunae, also called 'lateral lacunae' or 'lacunae laterales') in the dura mater near the sinus.

[citation needed] 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.

[citation needed] Most of the cerebral veins from the outer surface of the hemisphere open into these lacunæ, and numerous arachnoid granulations (Pacchionian bodies) project into them from below.

[citation needed] Cerebrospinal fluid drains through arachnoid granulations into the superior sagittal sinus and is returned to venous circulation.