What is the descending abdominal aorta?

The aorta is the large blood vessel that comes out of your heart and contains the blood that has been oxygenated in your lungs and is ready to go to the rest of your body. It is one big tube with smaller arteries coming off of it until it needs to split in two to reach the legs, at which point it becomes the two femoral arteries.

The aorta is shaped a bit like a question mark. Get out a piece of paper and a pencil, and start by drawing a short (a couple of inches) vertical line in the middle of the page. Now from the top of that line, continue it in an arch curving up and to the right, then back toward the middle of the page, then down, like a question mark. The line that goes up at the beginning is the ascending aorta, the middle more horizontal part is the arch, and when it turns and comes back down, it is the descending aorta.