Fig. 1
Cerebral (a, d), and extracranial (b, c, e) venous network: anatomical representation and lumped-parameter model. The 164 resistive elements (D and E) model 164 vessels. Flow inputs are indicated as arrows (Qc at cerebral level, Qf at femoral level, Qv at vertebral level). The following venous vessels were included in the model, distinguishing between the right (subscript r) and left (subscript l) vessel whenever appropriate: for the intracranial area (a), ophthalmic veins (OVl, OVr), basal veins of Rosenthal (RVl, RVr), internal cerebral veins (ICVl, ICVr), inferior sagittal sinus (ISS), superior sagittal sinus (SSS), great vein of Galen (GV), straight sinus (SRS), transverse sinuses (TSl, TSr), posterior occipital sinuses (POS, POSl, POSr), basilar plexus (BAl, BAr), cavernous sinuses (CSl, CSr), superior petrosal sinuses (SPSl, SPSr), inferior petrosal sinuses (IPSl, IPSr), sigmoid sinuses (SSl, SSr); for the extracranial area (a and b), internal jugular veins (IJVl, IJVr), vertebral veins (divided into six segments, VVl 1…6, VVr 1…6), cervical plexus (divided into seven segments plus two, CPa, CPp, CP 1…7; subscripts a and p stand for anterior and posterior, respectively), connective vessels between cervical plexus and vertebral veins (CPVVl 1…6, CPVVr 1…6), thoracic plexus (divided into twelve segments, TP 1…12), azygos vein (divided into twelve segments, AZ 1…12), connective vessels between thoracic plexus and azygos vein (TPAZ 1…12), inferior vena cava (divided into three segments, CV, CV1, CV2), lumbar plexus (divided into two segments, LP1, LP2), lumbar vein (divided into two segments, LV1, LV2) and connective vessels between lumbar plexus and lumbar veins (LPLV1, LPLV2)