Anatomical Overview and Imaging of the Aorta and Visceral Arteries
Gabriele Ironi, Giorgio Brembilla, Giulia Benedetti, Francesco De Cobelli
The thoracic aorta extends proximally from the aortic annulus to the diaphragmatic crura distally. It is subdivided into three parts: the ascending aorta, the arch and the descending aorta. The ascending aorta comprises the aortic root and the tubular ascending aorta. The aortic root lies between the aortic annulus and the sinotubular junction. The sinuses of Valsalva arise from the aortic root. The tubular ascending aorta runs from the sinotubular junction to the brachiocephalic trunk. The coronary arteries are the only branches of the ascending aorta. The aortic arch begins at the brachiocephalic trunk and ends at the origin of the left subclavian artery. The isthmus extends from the left subclavian artery to the ligamentum arteriosum. Three branches usually arise from the aortic arch: the brachiocephalic trunk, the left common carotid artery and the left subclavian artery. The brachiocephalic trunk divides into the right common carotid artery and the right subclavian artery. In 6% of people, the left vertebral artery arises directly from the arch . The bovine arch is another variant in which the left common carotid artery arises from the brachiocephalic trunk rather than the aorta . Another arch variant is the ductus diverticulum, a focal bulge along the inner aspect of the isthmus representing a remnant of the ductus arteriosus. Traumatic aortic transection also occurs in this location and can occasionally be difficult to differentiate from a ductus diverticulum. However, the ductus diverticulum has smooth margins with obtuse angles relative to the adjacent aorta. Aortic transection has irregular margins with acute angles relative to the nearby aortic walls.