The anatomic scheme of the anterior condylar confluence and surroundung venous complex. ACC: anterior condylar confluence, ACV: anterior condylar vein, CS: cavernous sinus, ICA: internal cerebral artery, IJV: internal jugular vein, IPS: inferior petrosal sinus, JB: jugular bulb, LCV: lateral condylar vein, PCV: posterior condylar vein, SS: sigmoid sinus, VVP: vertebral venous plexus, a: anastomotic channel with IJV or jugular bulb, b: anastomtic channel with IPS, c: anastomotic channel with branches from ICA venous plexus (Trolard’s inferior petro-occipital vein), d: anastomotic channel with prevertebral venous plexus, #: hypoglossal canal.