Figure 1 depicts the brain’s blood supply routes. The Carotid arteries – both internal and external branches – serve as main supply routes. Both originate from the common carotid artery; here we see the right side supply routes. We have a similar system on the left side too.

The outer external branch transports oxygen and food to the face and all over the skull; the inner branch transports to the inside of the brain.

The junction where the common carotid artery divides into two is a crucial place. It is the commonplace where fat deposits, a plaque develops, and then narrowing the route happens. We can hear a sound – “bruit” – using a stethoscope. They are at high risk of getting a stroke either by cutting off the blood supply or by dislodging plaque particles. The plaque particles can travel higher through blood further inside and may cut off blood supply to a smaller area of the brain. This type of stroke, which is the commonest type, is called an ischemic stroke.

Figure 2 (below) illustrates blood supply on the skull base.

Figure 3 shows the brain regions’ main supply routes: Anterior, middle, and cerebral. Knowing these supply areas is vey useful because the impairments due to an interruption to the blood supply in a stroke depends on which supply route is blocked.