Aorta Aortic arch Continuation of ascending aorta Curves upward, to the left and posteriorly, then downward, arching over left principal bronchus and pulmonary trunk to lower border of T4 level, to become descending aorta Branches(from right to left a Brachiocephalic trunk Left common carotid artery Left subclavian artel Aortic glomera-chemoreceptorAorta Aortic arch ◼ Continuation of ascending aorta ◼ Curves upward, to the left and posteriorly, then downward, arching over left principal bronchus and pulmonary trunk to lower border of T4 level, to become descending aorta ◼ Branches (from right to left ) ❑ Brachiocephalic trunk ❑ Left common carotid artery ❑ Left subclavian artery ◼ Aortic glomera－chemoreceptor