Aortic arch

The aortic arch (also known as arch of the aorta, Latin: arcus aortae) is the portion of the aorta between its ascending and descending parts. It lies within the mediastinum and gives rise to major blood vessels that supply the head and neck, and the upper limbs.

The aortic arch is the continuation of the ascending aorta. It begins at the level of the 2nd sternocostal joint when the ascending aorta emerges from the pericardium. This part of the aorta arches upward, backward, and to the left, travels through the superior mediastinum. The aortic arch ends on the left side at the level of 4th/5th thoracic vertebrae.

The arch of the aorta extends as high as the midlevel of the manubrium of the sternum. It is initially in front of and, finally, lateral to the trachea. Three branches arise from the superior side of the arch and all three are crossed anteriorly by the left brachiocephalic vein. In the order in which they branch off the aortic arch (from right to left), they are:

• Brachiocephalic trunk
• Left common carotid artery
• Left subclavian artery

The brachiocephalic trunk is the largest branch of the aortic arch. It arises behind the manubrium of the sternum, and divides further into two branches - the right subclavian artery and right common carotid artery. The right subclavian artery passes laterally, superior to the clavicle, and then runs underneath the clavicle, passing into the right upper limb supplying it. The right common carotid artery travels upwards on the right side of the neck, posteromedial to the internal jugular vein. It supplies arterial blood to the right side of the head and neck.

The left common carotid artery, unlike the right one (which branches off the brachiocephalic trunk), arises directly from the arch of the aorta. It originates to the left of the brachiocephalic trunk and ascends along the left side of the neck. The left common carotid artery provides arterial blood supply to the left side of the head and neck.

The left subclavian artery originates from the aortic arch to the left from the left common carotid artery. It ascends next to the left common carotid artery, both travel through the superior mediastinum on the left side of the trachea. The left subclavian artery mainly supplies the right upper limb. However, some branches of the subclavian arteries supply the thorax and head.