The ascending aorta is the first part of the aorta artery. Beginning at the aortic annulus, it arises from the heart left ventricle and extends to the aortic arch, which is the second part. The ascending aorta gives off two branches: the right and left coronary arteries that supply blood to the myocardium (heart muscle). At the union of the ascending aorta with the aortic arch the caliber of the vessel is increased due to a bulging of its right wall. Contained within the pericardium, the ascending aorta is covered by the trunk of the pulmonary artery as it comes off the heart. The aortic root is the portion of the ascending aorta beginning at the aortic annulus.