The internal carotid artery is one of two terminal branches of the common carotid artery. The main areas supplied by the branches of the internal carotid artery include the cerebral hemispheres, eyes, forehead, nose, nasal cavity and paranasal sinuses. This artery does not supply any neck structures. Also, the internal carotid arteries contribute to the anterior circulation system of the brain and, together with the posterior circulation system, form the circle of Willis.