Systemic or general circulation

The blood pumped out from the left ventricle is carried by the branches of the aorta around the body and returns to the right atrium of the heart by the superior and inferior venae curiae.  shows the general positions of the aorta and the main arteries of the limbs. provides an overview of the venae cavae and the veins of the limbs. The circulation of blood to the different parts of the body will be described in the order in which their arteries branch off the aorta.
Aorta The aorta  begins at the upper part of the left ventricle and, after passing upwards for a short way, it arches backwards and to the left. It then descends behind the heart through the thoracic cavity a little to the left of the thoracic vertebrae. At the level of the 12th thoracic vertebra it passes behind the diaphragm then downwards in the abdominal cavity to the level of the 4th lumbar vertebra, where it divides into the right and left common iliac arteries. Throughout its length the aorta gives off numerous branches. Some of the branches are paired, i.e. there is a 
right and left branch of the same name, for instance; the right and left renal arteries supplying the kidneys; and some are single or unpaired, e.g. the coeliac artery. The aorta will be described here according to location: 
• thoracic aorta (see below) 1 
• abdominal aorta . 1 Thoracic aorta This part of the aorta lies above the diaphragm and is] described in three parts: 
• ascending aorta
• arch of the aorta 
• descending aorta in the thorax. Ascending aorta This is the short section of the aorta that rises from; the heart. It is about 5 cm long and lies behind the
sternum. The right and left coronary arteries are its only branches; and they arise from the aorta just above the level of the aortic valve These important arteries supply the myocardium.