Cut Section of the Skull Revealing the Venous Lacunae

Description

Cut calvaria exposes the midline dura mater and the superior sagittal sinus (sinus sagittalis superior) coursing anteroposteriorly along the attached margin of the falx cerebri. On either side, venous lacunae (lacunae laterales) form irregular, laterally placed dural reservoirs that sit superficial to the cerebral convexities and communicate medially with the sinus. Bridging superior cerebral veins traverse from the cortical surface through the subarachnoid space and arachnoid mater to pierce the dura and empty into the lacunae and sinus, with the gyri and major sulci of the cerebral hemispheres visible deep to these meningeal layers. A midline landmark. This relationship matters because the lacunae house clusters of arachnoid granulations, a common site of cerebrospinal fluid resorption and a frequent cause of parasagittal “granulation pits” and focal thinning on the inner table that can be mistaken for lytic lesions on CT. From a surgical standpoint, parasagittal craniotomy planning hinges on appreciating how bridging veins and lateral lacunae can extend farther laterally than the sinus itself, raising the risk of venous infarction or troublesome dural bleeding if the bone flap crosses these channels. It also helps explain why traumatic tears near the sagittal suture can produce extra-axial hemorrhage patterns that do not respect the midline when lacunar spaces are involved. Use this asset in neuroanatomy and meningeal teaching blocks to clarify dural venous sinus anatomy, in radiology primers discussing arachnoid granulations versus pathology, and in neurosurgical atlases covering interhemispheric and parasagittal approaches with emphasis on bridging vein preservation. Anatomical accuracy verified by SciePro's Medical Advisory Board.