Which statement about the third branch of the aortic arch is true?

Which statement about the third branch of the aortic arch is true?

• A. Right subclavian artery
• B. Left common carotid artery
• C. Left subclavian artery
• D. Brachiocephalic trunk

Answer: (C)

The main idea here is the normal arrangement of the major branches of the aortic arch in the adult. As the arch curves, three primary branches arise in sequence: first the brachiocephalic trunk, which gives rise to the right subclavian and right common carotid; second the left common carotid; and third the left subclavian. So the third branch is the left subclavian artery, which supplies the left upper limb and becomes the axillary artery after crossing the first rib. The right subclavian isn’t a direct branch of the arch (it comes from the brachiocephalic trunk), and the left common carotid is the second branch, not the last.

The main idea here is the normal arrangement of the major branches of the aortic arch in the adult. As the arch curves, three primary branches arise in sequence: first the brachiocephalic trunk, which gives rise to the right subclavian and right common carotid; second the left common carotid; and third the left subclavian. So the third branch is the left subclavian artery, which supplies the left upper limb and becomes the axillary artery after crossing the first rib. The right subclavian isn’t a direct branch of the arch (it comes from the brachiocephalic trunk), and the left common carotid is the second branch, not the last.