Venous Lacunae

Description

Superior to the cerebral hemispheres, the superior sagittal sinus runs in the midline within the attached margin of the falx cerebri, and the venous lacunae form irregular, laterally placed expansions that parallel it on either side. Bridging veins from the superficial cerebral cortex traverse the subdural space to enter the sinus and lacunae, while arachnoid granulations project into these dural venous spaces as pale intraluminal nodules. Cortical gyri and sulci provide the surface landmarks, with meningeal layers and adjacent diploic veins implied by the venous reservoirs along the inner table of the calvaria. Venous lacunae matter because they are the common receiving sites for parasagittal bridging veins and for cerebrospinal fluid resorption via arachnoid granulations, so pathology here combines venous outflow issues with raised intracranial pressure. This is where bridging veins tear in subdural hematoma, and where superior sagittal sinus thrombosis can extend laterally into lacunae, producing parasagittal venous infarcts that often present with leg-predominant motor deficits from involvement of the medial frontal cortex. A surgical landmark. During craniotomy near the midline, injury to these thin-walled venous spaces can cause brisk bleeding and complicate dural opening. Neurologic anatomy and neurosurgery teaching benefit from this depiction when explaining dural venous sinus anatomy, CSF dynamics, and the route of cortical venous drainage into the superior sagittal sinus complex. It also supports figures for radiology or pathology texts that correlate parasagittal extra-axial collections and venous sinus thrombosis on CT or MR venography with the underlying anatomy. Anatomical accuracy verified by SciePro's Medical Advisory Board.