Incidental Intracranial Aneurysm in a Dog Detected by 16-Multidetector Row Computed Tomography Angiography

Figure 5

The drawing shows the blood flow to the Circle of Willis from the three vessels: 1, basilar artery (BA), and 2, internal carotid arteries (ICAs). From internal carotid arteries, blood flows from circle of Willis to the brain through the rostral cerebral arteries (RCA). The anterior communicating artery that connects the two anterior cerebral arteries in humans is rarely described in dogs. However, either the canine rostral cerebral artery can be subdivided into a pre-joining point (R1) and, generally, in a single median R2 segment (post-joining). Internal carotid artery gives off the median cerebral arteries (MCAs) and the caudal communicating arteries (CCoAs), that connect the circle with the basilar artery. In most dogs, the caudal cerebral artery (CCA) and the rostral cerebellar artery (RcAs) are from the caudal communicating artery.