The Arch of the Aorta

Key points

• • The arch of the aorta continues from the ascending aorta, arches backward and to the left over the root of the left lung, and becomes the descending aorta.
• • It gives off three great branches: the brachiocephalic trunk, the left common carotid artery and the left subclavian artery, supplying the head, neck and arms.
• • The left recurrent laryngeal nerve hooks under the arch, around the ligamentum arteriosum, so an aortic problem can stretch it and cause hoarseness.
• • The ligamentum arteriosum is the remnant of the fetal ductus arteriosus and tethers the arch to the pulmonary artery.
• • The arch wall carries baroreceptors that sense blood pressure, while nearby aortic bodies act as chemoreceptors sensing blood gases, both feeding back to the brainstem.
• • Because the arch is fixed at the ligamentum arteriosum while the heart is mobile, a sudden deceleration injury tends to tear the aorta at the isthmus, just beyond the left subclavian artery near the ligamentum arteriosum.