hi let's talk about the superior mediastinum in this video we'll discuss the major contents of
the superior mediastinum as you may recall the superior mediastinum is the superior portion
of the mediastinum its borders include the first rib and superior thoracic inlet
so that's going to be more antero superior posteriorly we have thoracic vertebrae two three
and four at least their bodies and then inferiorly we have the thoracic plane that's the plane
that's prescribed by the line between the sternal angle and the intervertebral disc between t4 and
t5 now over here we can see the rough borders of the superior mediastinum but i want you to keep
in mind that this is a little deceptive because that manubrium is back at an angle so there's more
of a wedge shape to that than a cube let's take a look at some of the contents and we can move from
anterior or superficial to posterior or deep and take a look at what we can see so there is the
superior vena cava draining into the right atrium that superior vena cava has tributaries
of the right brachiocephalic vein the left brachiocephalic vein which is cut and reflected
away here but which would normally traverse this space we can also see a little bit of the azygos
vein there we'll detail that in the posterior mediastinum we can see the arch of the aorta
and its major branches so the proximal portions of the brachiocephalic trunk
the left common carotid artery and the left subclavian artery are within this space we can
also see the vagus nerves descending down from the carotid sheath to enter into this space as well
as we move a little deeper there's one component here that is pretty superficial
and this is reflected upwards this is an example of thymic fat which is the replacement for the
thymus gland which would normally overlay this region it involutes post-puberty and
goes through a process of fibrosis and turns into connective tissue which is what you see there we
can still see the superior vena cava the arch of the aorta here we can also see moving toward the
superior mediastinum the pulmonary trunk and that bifurcates into the pulmonary arteries
left and right and in association with that right pulmonary artery we can see this
structure that's the ligamentum arteriosum which is a remnant of the ductus arteriosus
which conducts blood from the origin of the right pulmonary artery to the arch of the aorta
in utero so that's a way to bypass pulmonary circulation here it's just a fibrous ligament
however moving deeper we can see the trachea and behind the trachea we can see the esophagus that
muscular tube heading down towards the stomach the trachea is going to bifurcate at about the level
of the thoracic plane so we've got the carina there that helps to direct air traffic between
the right main stem bronchus and the left main stem bronchus we can see further there's a vagus
nerve the left vagus nerve giving off the left recurrent laryngeal nerve the right vagus nerve is
in a little closer approximation there it's it's a little out of view but it's going to
be wrapping around there we can see the phrenic nerves so there's one phrenic nerve there is
the other phrenic nerve just on the borders of the superior mediastinum and we we can't
get a good look at it here but moving up in this tracheoesophageal groove and then crossing over
from left to right before ascending again is going to be the thoracic duct of the lymphatic system
and speaking of lymphatics we'll find some lymph nodes in this region so tracheobronchial nodes
around here these are going to feed into bronchomediastinal trunks which will ascend
the superior mediastinum heading towards the venous angles at the uh the root of the neck
so we've discussed the boundaries of the superior mediastinum and some of the major contents again
please do pay close attention to that thoracic plane that's going to give you a lot of guidance
with respect to to how to navigate this space this is your summary slide thank you for your time