Morphological study of sinus flow in the confluence of sinuses

The confluence of sinuses (CS; torcular herophili) is represented by the junction of the superior sagittal (SSS), straight (SS), occipital (OS), and two transverse sinuses (TS). The objective of this study was to interpret sinus flow around the CS by morphological investigation of the sinuses. This study is based on visual examination of dural venous sinuses in the region of the CS in 31 adult cadavers. In the inflow zone, we examined the direction of SSS and SS flow. In the communication zone, we examined the extent to which outflow sinuses communicate with other sinuses. In the outflow zone, we used the diameters of outflow sinuses to determine anatomical dominance. The SSS entered the CS via the right TS in 16 cases (51.6%) and via the center of the CS in 14 cases (45.2%). The SS entered via the center of the CS in 18 cases (58.1%) and via the left TS in 11 cases (35.5%). Outflow sinuses communicated freely in 26 cases (83.8%) and communicated partially in five cases (16.2%). Partial communication was the result of a septate CS. In terms of outflow, the right TS was dominant in 11 cases (35.5%), and in 18 cases (58.1%), outflow was symmetrical. The direction of SSS inflow was different from that of SS inflow, and partial communication was observed in five cases (16.1%). Therefore, the presence of a septum may be considered an anatomical factor, with implications in diagnosis or in the sacrifice of the outflow sinus of the CS.