After the carotid siphon, which arteries arise from the internal carotid?

• A. Anterior cerebral and middle cerebral arteries
• B. Posterior cerebral and basilar arteries
• C. Ophthalmic and posterior communicating arteries
• D. Superior cerebellar and anterior inferior cerebellar arteries

Answer: (A)

The key idea is that the internal carotid artery, after passing through the carotid siphon, gives rise to the two terminal arteries that supply the cerebral hemispheres’ anterior circulation: the anterior cerebral artery and the middle cerebral artery. These arteries continue the internal carotid’s intracranial path to supply most of the frontal, parietal, and some temporal regions.

Ophthalmic arteries come off earlier, from the intracranial/internal carotid before the siphon, supplying the eye and orbit. The posterior communicating arteries are connections that link the internal carotid to the posterior circulation and are not the main intracranial branches arising after the siphon. The posterior cerebral arteries and basilar artery belong to the posterior circulation; the cerebellar arteries come off the basilar artery, not directly from the internal carotid after the siphon.

So the arteries arising from the internal carotid after the siphon are the anterior cerebral and middle cerebral arteries.