Anatomy: Mediastinum: Cross Section

Representative Levels of Cross Sections of the Thorax

These cross sections are arranged so that the right side of the body is on your left. This is how you will examine CAT scans and MRI's if you are heading for the clinical profession. This is difficult for many people but it is something you have to set your mind to at the very beginning of studying cross sections. It might help if you pretend that you are looking at a person, patient or a cadaver lying on a bed. You are standing at their feet and looking up towards their head. Now imagine a section taken from any part of the body, in this case the thorax, and keep in mind where that person's or cadaver's right and left arms are. With practice, it will become second nature to you. Knowing left from right is very important, particulary if you are going to be in a medical profession. I am sure you wouldn't want to cut off the wrong limb or remove the wrong kidney. It has happened, but fortunately rarely.

Cross section through the thorax at vertebra T2This section cuts through the superior mediastinum above the aortic arch.
Cross section through the thorax at vertebra T3.This section is also through the superior mediastinum but a little lower than the one above. You are looking up and into the aortic arch. Although not labeled, you should be able to make out the openings of the brachiocephalic, left common carotid and left subclavian arteries.
Cross section through the thorax at vertebra T5.This section cuts through the anterior, middle and posterior mediastina. You now see the ascending and descending aortae as well as the pulmonary trunk.
Cross section through the thorax at vertebra T8.This section cuts through the heart in such a way that all four chambers of the heart are seen. You should also be able to differentiate the anterior, middle and posterior parts of the inferior mediastinum.
Cross section through the thorax at vertebra T9.This section is taken just below the one above except that you are now beginning to cut into the abdomen. On the right side, you can see a piece of the liver which is just beneath the diaphragm. The dome of the right diaphragm is usually higher because of the massive liver below it.