Superior Mediastinum

00:00 sides, vein is the inferior most structure. The last part is the mediastinum. This is the superior mediastinum, inferior mediastinum. The superior mediastinum is not further subdivided, but the inferior mediastinum is subdivided into anterior, middle, and posterior.

00:19 So one of the questions you get in the exam is contents of the superior mediastinum. One of the things you can think of the superior mediastinum, very logical. Anything that is going into thorax, anything coming out of thorax has to be in the superior mediastinum.

00:35 So, your brachiocephalic trunk, subclavian artery, the left common carotid, your brachiocephalic vein joining in, vagus nerve, phrenic nerve, superior vena cava, what else? Esophagus, trachea, they’re all there. Thoracic duct.

00:55 Thoracic duct, yeah. Anything you can think of in the root of the neck to the thorax, it has to be there. There’s nothing which is not there. When it comes to the inferior mediastinum, you need to be careful. Inferior mediastinum, the mediastinum in that area, what essentially that implies is, if you take your thorax and take the lungs off, that bit is your mediastinum. So imagine, this is thorax, and if we take both the lungs to the sides, whatever is remaining is the mediastinum. So the heart is part of the mediastinum and it is part of the middle mediastinum. So, heart is the most important content in the middle mediastinum. Anterior mediastinum does not have anything significant. It has got some lymph nodes, some fat, and the thymus. Middle mediastinum has got most of the structures in relation to the heart. Anything you can think of with the heart will be in the middle mediastinum. I've mentioned, if you remember the phrenic nerve I said that lies over the heart, so that is also the middle mediastinum. The way to remember the middle mediastinum is to remember that nothing important in the anterior mediastinum. So take it off in your thought process. Then think, what is in the posterior mediastinum? If you go back in the posterior mediastinum, what do you think it could be? Trachea, esophagus. Trachea, esophagus. Well, trachea is not there.

02:31 Do you know why? Because trachea is already bifurcated. Yeah, trachea is not there.

02:35 Esophagus, whenever you think esophagus, think vagus, because vagus is going towards food, towards the stomach, towards abdomen. So vagus. So you have the right vagus and the left vagus.

02:46 They are in the posterior mediastinum. What else? Inferior vena cava or something? No. Inferior vena cava does not really enter the mediastinum because inferior vena cava enters T8 and immediately goes to the heart. So it’s not part of the mediastinum.

03:01 Descending aorta. Descending aorta. Descending aorta is in the inferior mediastinum. So whenever you think aorta, what are the other two structures you need to think immediately? Thoracic duct and azygos vein, because remember, you are in the diaphragm. These are the three structures coming out through the diaphragm, abdominal aorta, thoracic duct, and azygos vein. So these three structures are in the posterior mediastinum, as well as the esophagus and the two vagus. If you remember the six structures, I don’t think you will go wrong.

03:41 Two vagus. Correct, yeah, two vagus, yeah. Anything apart from this goes for the middle mediastinum. Finally, the lung surface markings you don’t