The structure indicated is the internal carotid artery.

The internal carotid arteries arise from the common carotid arteries.

The brachiocephalic artery arises from the arch of the aorta and divides into the right subclavian artery and the right common carotid artery.

There is no left brachiocephalic artery however, and the left common carotid arises directly from the aortic arch. There are three branches which come off the aortic arch:

1. Brachiocephalic artery
2. Left common carotid
3. Left subclavian

The common carotid arteries then divide into the external carotid and internal carotid arteries. The internal carotid artery ascends to supply the brain, joining the circle of Willis. The external carotid artery supplies the structures of the head and face.

The internal carotid arteries consists of 7 segments:

1. Cervical segment (C1)
2. Petrous segment (C2)
3. Lacerum segment (C3)
4. Cavernous segment (C4)
5. Clinoid segment (C5)
6. Ophthalmic segment (C6)
7. Communicating segment (C7)