Morphology of the Willis chords in the superior sagittal sinus during various periods of life.

UNLABELLED Numerous fibrous elements known as the Willis chords are situated in the light of the superior sagittal sinus. The paper is aimed at a comparative evaluation of the appearance of the Willis chords appearing in the superior sagittal sinus during various periods of human life and a determination of their role. The material comprises 200 brains at the foetal period as well as 200 adult and senile brains. The experimental methods include injection methods, infrared light, the Pickworth method and computer image analysis. During adulthood, various elements such as valvulae, divisions, plates, beams and arachnoidal granulation are situated in the light of superior sagittal sinus. The number of arachnoidal granulations increases continuously due to age, new ones appearing close to those already in existence and old granulation spreading. The superior sagittal sinus contains numerous valvulae similar to the feedback flaps typical for hydraulic systems. Divisions act as orifices which lead to a fall in pressure and induce blood into the sinus. Large differences between the cross-sections of meningeal veins and bridge veins were noticed, which resembles the structure of ejector. The blood flow in the bridge veins ending at the superior sagittal sinus is controlled by the valvulae and their geometrical form changes according to age. CONCLUSION The Willis chords situated in the superior sagittal sinus may control the circulation. Their number grows with age and their morphology changes.