Fig. 5: CVS model architecture: focus on the cerebrovascular and ocular compartments.

The 1D arterial network (red vessels, the upper aortic-vertebral, and carotid branches are reported here as a magnification of the entire arterial network, on the left) is connected to the 0D lumped-parameter head, cerebral, and ocular compartments (Zc denotes lumped characteristic impedances). ECA,l, and ECA,r represent the left and right external carotid arteries, connected to the extra-cerebral head circulation, where H,v denotes (extra-cerebral) head veins. Left and right internal carotid arteries are denoted as ICA,l and ICA,r while VA,l and VA,r represent the left and right vertebral arteries, respectively (BA indicates the basal artery). For the left (l) cerebrovascular circulation, ACA, MCA, and PCA indicate the anterior, middle, and posterior large (proximal) cerebral arteries, while da, dm, and dp denote distal anterior, middle, and posterior arteries, respectively. The right (r) cerebral circulation is symmetric to the left side and not represented here for simplicity. Compartments ccap, cv, and dvs refer to the cerebral capillaries, cerebral veins, and dural venous sinus, respectively. Qf and Qo are the cerebrospinal fluid formation and outflow rates, respectively, while CBF represents the cerebral blood flow rate and ICP denotes the intracranial pressure. In the ocular compartment, IOP denotes the intraocular pressure, whereas pa,eye, pv,eye, Qaq,in, and Qaq,out indicate the arterial and venous pressures at the level of the eye and the aqueous humor inflow and outflow rates, respectively.