The aorta is the largest artery of your body, and it is a strong and sturdy vessel. In this lesson, you will learn about its downward path through the chest and abdomen and discover the organs and structures supplied by its branches.
The largest artery in your body is called the aorta. We previously learned that it originates at the left ventricle of the heart and ascends a short distance before making a U-turn at the aortic arch and plunging downward through your chest, which is referred to as the thorax, and into your abdomen. In this lesson, you will learn about the descending aorta, which begins at the aortic arch and is divided into two sections, the thoracic and the abdominal aorta.
The main thing to note about the descending aorta is that it has a number of branches coming off of it, much like back roads would come off of a highway. These branches feed the organs and structures within the thorax and abdomen before terminating into two final branches that eventually supply the legs.
The aorta is a very large artery and where it originates, right off of the left ventricle of the heart, it's about the size of a garden hose. It maintains this large size and decreases only slightly in size as it runs down through your body to its end. The different sections of the aorta are named for their location.
The thoracic aorta feeds many structures in the chest area
Therefore, we see that the section that runs through your thorax is named the thoracic aorta. This portion of the aorta spans from the aortic arch to the level of the diaphragm. The thoracic aorta has a number of paired blood vessels that branch off like back roads off of a highway. If you think about the organs and structures that are found in your chest, you will easily be able to tell where these branches travel.
For instance, there's a paired branch of arteries that come off of the thoracic aorta that feed the lungs. There are branches that feed your esophagus, which lies deep and runs through your thoracic cavity. There are also branches that feed the surrounding structures, including the diaphragm, which lies at the bottom of the thoracic region, just below the lungs and just above the liver.
The abdominal aorta is the next section of the aorta, and it travels from the diaphragm through the abdominal cavity. It travels just anterior to your spinal column. In fact, it travels so close to your spine that it traces the natural curve of your lumbar spine.
Location of the abdominal aorta
The first branch off of the abdominal aorta is called the celiac trunk. You can recall this term by remembering that the word 'celiac' is the anatomical term that refers to the abdomen. The celiac trunk is a single vessel, but it has three branches. If you think about the abdominal aorta as a major highway, then the celiac trunk can be thought of as an exit ramp that leads to three back roads. Here again, if you think about the organs and structures that are found in the top portion of your abdomen, then you will have a good idea of what these back roads, or branches, feed. What we find is that the branches supply blood to the stomach, the spleen, the pancreas, and the liver.
Additional branches off of the abdominal aorta supply the remaining organs and structures of the abdomen, including the intestines, kidneys, reproductive organs, and muscles of the region. These branches are not simply named branch 1, branch 2, branch 3, but their naming system is still pretty easy to remember. The reason that it's easy to remember is because these branches are often named for the organs or area that they supply. For instance, the term 'renal' stands for 'kidneys,' and the renal arteries come directly off of the abdominal aorta and serve the kidneys.
At this point, we have come to the end of the abdominal aorta as it splits into two final branches called the right and left common iliac arteries. The term 'iliac' comes from the fact that the vessels are situated near the large pelvic bone called the ilium. These arteries split at the level of the pelvis and travel down toward each leg. Therefore, they supply blood to the pelvic organs and legs. This would include the bladder, rectum, reproductive organs, and muscles of the lower extremities.
Location of the common iliac arteries
Let's review. After exiting the heart, the aorta makes a U-turn at the aortic arch and becomes known as the descending aorta as it plunges down through the thorax and abdomen. The descending aorta is divided into two sections that are named for their location. The thoracic aorta is the part that travels through your thorax and spans from the aortic arch to the level of the diaphragm. Its branches feed organs and structures in your chest, such as the lungs, esophagus, and diaphragm.
The abdominal aorta starts at the diaphragm and travels through the abdomen. Like the thoracic aorta, the abdominal aorta has many branches that supply blood to the surrounding structures. The first branch off of the abdominal aorta is called the celiac trunk. This vessel is like a large exit ramp that splits into three back roads. These branching back roads supply blood to the stomach, spleen, pancreas, and liver.
There are other branches that come directly off the abdominal aorta, and they are usually named for the organs and region they supply. For example, the kidneys are supplied by the renal arteries. The common iliac arteries are the terminal branches of the abdominal aorta. They supply blood to the pelvic organs and legs.
At the end of this lesson, you'll be able to describe the structure and function of the descending aorta's branches: the thoracic and abdominal aortas.