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.
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.
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, 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. Well, trachea is not there.
Do you know why? Because trachea is already
bifurcated. Yeah, trachea is not there.
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.
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.
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
Two vagus. Correct, yeah, two vagus, yeah.
from this goes for the middle mediastinum.
Finally, the lung surface markings you don’t