Aorta
The aorta ( ) is the main artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes oxygenated blood to all parts of the body through the systemic circulation.
Aortic arch
The final section of the aortic arch is known as the "isthmus of aorta". This is so called because it is a narrowing (isthmus) of the aorta as a result of decreased blood flow when in foetal life. As the left ventricle of the heart increases in size throughout life, the narrowing eventually dilates to become a normal size. If this does not occur, this can result in coarctation of the aorta. The ductus arteriosus connects to the final section of the arch in foetal life and the ligamentum arteriosum when the ductus arteriosus regresses.