Anatomy of the falcine sinus during the prenatal period.
The falcine sinus in the falx cerebri is rarely encountered in adults, appearings in approximately 2.1% of CT examinations of adult patients. Some authors have studied the plexus rather than the sinus, a rare form of the venous pathway between the layers of the cerebral falx, which connects the superior sagittal sinus with the inferior sagittal sinus and the straight sinus. The aim of this study was to analyse the anatomy of the falcine sinus in the prenatal period, which will fill a gap in the literature. This study consisted of 50 foetuses with a v-tube length of 89-229 mm and the equivalent of 15-28 weeks of intrauterine development on the Scammon and Calkins scale. Blood vessels were filled with latex LBS 3022, and analysis was performed using the Scion Image for Windows 4.0.3.2 and Image J. We used various linear and nonlinear transformations. In 20 cases, intraventricular and periventricular haemorrhages were detected. The other cases showed sinuses in the cerebral falx, specifically in the back parts of the falx, and were described as oblique, straight, wavy, or network. A very rich venous network is located around the superior sagittal sinus; the middle section grew twice its length and the back section grew three times its width, reaching the lowest areas of the cerebral falx, the inferior sagittal sinus, and the straight sinus. Anastomotic intersinual loops appeared. There were three forms of venous weave crescents: isolated limited to the area adjacent to the superior sagittal sinus, partly merging with the straight sinus and a fully developed falcine sinus, which appeared in the older age groups with the most primitive forms being plexiform. Their remains a plurality of channels within the same superior sagittal sinus that show a predominance in the posterior segment. The location of the falcine sinus has been mostly associated with the rear one-third of the cerebral falx and should be considered during neurosurgery, because the front two-thirds of the cerebral falx are called the "safe zone". Knowledge of the falcine sinus anatomy is important for descriptions in neuroimaging examinations.