Meet John, a 54-year-old man who had a special map of his brain's blood vessels made. This map, called a computed tomography angiogram (CTA), showed something unique. John's left posterior cerebral artery (PCA) wasn't just getting blood from the vertebrobasilar system, like most people. It also had a link to the internal carotid artery (ICA). This connection was made through a vessel called the posterior communicating artery (PComA), which started 7 mm away from where the PCA normally begins. Even more interesting, there was an extra vessel that branched off the ICA, 4. 2 mm away from the PComA's start. This extra vessel was called an accessory posterior cerebral artery (APCA), which is like a super-powered version of the anterior choroidal artery (AChA).

Why is this important? Well, the brain's blood supply is like a network of highways. Normally, the PCA's territory gets blood from either the ICA or the vertebrobasilar system, but not both. John's brain had a unique highway system where these two major roads connected. This isn't too common, making John's brain a special case study. Understanding these kinds of variations can help doctors better understand how blood flows through different brains, which can be crucial in treating conditions like strokes.

The Unusual Journey of Blood in the Brain

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