The aorta is the largest blood vessel in the body. It is an artery that directly arises from the heart itself and descends through the thorax and into the abdomen. All the arteries of the body, save the pulmonary arteries, stem from the aorta or one of its main branches. This article aims to highlight the path of the aorta from its origins up until the main branches in both the thoracic and abdominal cavities. It should be noted that there are three ways of systematically approaching the aorta and each of these learning strategies will be mentioned here.
The Regional Approach
This is the most simple way of dividing the aorta and its branches, however it is suggested that unless you are a seasoned anatomist, one of the other methods should be looked at first, for clarity. Here, the aorta and its main branches are divided into the thoracic aorta and the abdominal aorta, which happen to be separated by the diaphragm.
The Seven Sections Approach
This is the most complex of the three strategies, but for first time students it is comprehensive and will give any anatomist a solid base of aortic knowledge. The aorta is divided up into seven sections which are listed below:
- The aortic valve which is situated in the posterior superior wall of the left ventricle;
- The aortic root which exists between the aortic valve and the sinotubular junction;
- The ascending aorta which can be seen between the sinotubular junction and the brachiocephalic artery, which is the largest of the aortic branches. The ascending aorta is contained within the pericardial sac and is covered by a visceral layer of serous pericardium.
- The aortic arch or transverse aorta gives three branches which supply the head and upper limbs. They are the brachiocephalic artery, the common carotid artery and the left subclavian artery;
- The descending thoracic aorta runs between the left subclavian artery and the first branch of the abdominal aorta which is the celiac artery. It is situated posteriorly in the thorax, close to the vertebral column to which it offers a blood supply;
- The abdominal aorta starts with the celiac artery and continues with the superior mesenteric artery, the left and right renal arteries and the inferior mesenteric artery. It supplies all the major organs of the abdomen;
- The thoracoabdominal aorta is the last section, which starts at the level of the last abdominal branch and ends at the bifurcation of the aorta into the left and right common iliac arteries;
The Aortic Directions Approach
This final method is both simple and yet detailed. It is based on the directions of the aorta, its ascension, arch and descending part, with no regard for which somatic region it is in or what major branches are formed. It does however lack sufficient details about the abdominal pathway of the aorta and for that reason it is suggested that this method becomes a secondary means if not combined with the seven sections approach.
- The ascending aorta starts at the aortic valve and finishes at the level of the second right sternocostal joint.
- The aortic arch begins from the end of the previous section and continues to ascend into an arch which goes to the left of the mediastinum. It can be found in front of the right pulmonary artery and the bifurcation of the trachea. It surpasses the base of the right lung and finishes at the level of the thoracic vertebra T4.
- The descending aorta begins at the level of the T4 vertebra and descends on the left side of the thoracic vertebrae from T5 until T12. It runs behind the base of the left lung and the pericardium, entering the abdomen via the aortic hiatus of the diaphragm when it reaches T12. Its branches include the bronchial artery, the pericardial artery, the superior phrenic artery, the esophageal artery, the posterior intercostal artery and the subcostal artery.