Which statement about the external carotid artery (ECA) versus the internal carotid artery (ICA) is true?

Which statement about the external carotid artery (ECA) versus the internal carotid artery (ICA) is true?

• A. ECA is typically anterior and medial to ICA
• B. ECA supplies brain predominantly
• C. ECA is typically posterior to ICA
• D. ECA has no branches

Answer: (A)

The key idea here is the spatial relationship between the external carotid artery (ECA) and the internal carotid artery (ICA) in the neck. In a typical arrangement, the external carotid artery lies in front of the internal carotid artery and is closer to the midline, with the internal carotid running more posteriorly and laterally toward the skull. So the ECA is anterior and medial to the ICA, while the ICA is behind and somewhat lateral. This matters because the brain’s blood supply comes mainly from the internal carotid arteries, which is why a statement claiming the external carotid supplies the brain predominantly isn’t correct. The external carotid has many neck and facial branches, unlike the internal carotid in the neck, which has no branches.

The key idea here is the spatial relationship between the external carotid artery (ECA) and the internal carotid artery (ICA) in the neck. In a typical arrangement, the external carotid artery lies in front of the internal carotid artery and is closer to the midline, with the internal carotid running more posteriorly and laterally toward the skull. So the ECA is anterior and medial to the ICA, while the ICA is behind and somewhat lateral.

This matters because the brain’s blood supply comes mainly from the internal carotid arteries, which is why a statement claiming the external carotid supplies the brain predominantly isn’t correct. The external carotid has many neck and facial branches, unlike the internal carotid in the neck, which has no branches.