Venous Malformation Receiving Brain Cortical Drainage

often a good idea to check if a facial “venous malformation” is somehow “connected” to the brain — basically is the malformation receiving brain venous drainage. Especially in the temporalis and nasal bridge / periorbital areas

Typical MRI for right masseter/temporal venous malformation. Atypically large round structure in middle of head…

Question: What normal intracranial venous structure is not sufficiently developed — and what relationship could that have with everything else?