hi let's talk about the diaphragm in this video i'll describe the basic structure
of the diaphragm and identify its neurovascular supply so the diaphragm is a musculofibrous sheet
that's going to separate the thoracic cavity from the abdominopelvic cavity that muscular fiber
sheet has a bimodal dome shape to it so on the donor right side that consists of the most robust
right cupula separated from the less robust left cupula and the two cupula cupili are
separated by the central tendon that central tendon has a very close physical relationship
in fact it's bonded to the fibrous pericardium now if we think about the relationship of the
abdominal pelvic viscera that kind of helps to understand the shape of the diaphragm and we'll
get to these organs in the gi sessions but deep to the right cupula we have the right lobe of
the liver which is very robust as well as the right kidney in there and super renal gland um
those are more associated with the posterior aspect of the diaphragm rather than the the
cupula itself deep to the left cupula we can see a little bit of it here we have the left lobe of the
diaphragm we also have the fundus of the stomach so if you can see the esophagus going in there
the fundus of the stomach is right there we'll also have adjacent to that the spleen and the
left kidney and superno gland in that vicinity so the diaphragm itself is the major muscle
of respiration so it contracting is going to increase the volume of the thoracic cavity thereby
decreasing pressure thereby allowing air to flow into the lungs and it's able to do so because
its attachment is all along the thoracic outlet the thoracic inlet is that space between the uh
the first ribs and the manubrium and the first thoracic vertebrae and the thoracic outlet
is that space lining the the division between thoracic and abdominal pelvic cavities so that
includes the costal margin here and the lateral margins of ribs 11 and 12 as well as the crura
of the diaphragm which extend down to the third lumbar vertebra as we'll see now this is a view
of the inferior surface of the diaphragm this would be the surface that is in contact
with the abdominal pelvic cavity and we can see that there are one
two three apertures through the diaphragm that are going to conduct
some very important neurovasculature so the first aperture that i'd like us to discuss
is the cable opening that cable opening is the space through which the inferior vena cava
is going to pass on its way up into the right atrium of the heart also through this aperture
is going to be a branch of the right phrenic nerve and some lymphatics this cable opening is the
highest of the three apertures at t8 left lateral and a little posterior to the cable opening
is the esophageal hiatus the esophageal hiatus is the space through which the esophagus
is transmitted also in association with the esophagus are going to be the vagal trunks
both anterior and posterior an esophageal branch of the left gastric artery is going to ascend
because that's a branch of the celiac trunk up through that esophageal hiatus to follow the
esophagus and there will also be some lymphatics now keep in mind those vagal are going to be
innervating the gut tube so it's a good thing that they're traveling along with the esophagus
the esophageal hiatus is two vertebral levels down at t10 and then finally we have the aortic itis
the aortic hiatus is less of a an aperture through more of an aperture behind the diaphragm so if
we're to actually pay attention to what's going on here here is the posterior margin of the diaphragm
and we have a left crease and a right crease here and the margins of these crura come down to l3
and there's this nice teardrop space through which the aorta can transition between thoracic
and abdominal parts now along with that descending aorta we're going to have the thoracic duct
ascending through that space we'll also have a branch of the azygos system
ascending through that space as well and it's important to note that the thoracic splanchnic
nerves will be transmitted in this vicinity but they don't travel through the aortic itis they
are going to pierce through the left and right crore themselves
and then finally the the sympathetic trunks are also going to travel posterior to the diaphragm
as well just lateral to the carrera on the they'll share a nice lateral relationship to the vertebral
bodies as we'll see so that aorticitis is at t12 so cavalier 8 esophageal at 10 and aortic at 12.
in terms of the neurovasculature we should think about both the superior and inferior surface
of the diaphragm the nerves that innervate the diaphragm or that innervate each hemidiaphragm
are the phrenic nerves the phrenic nerves are predominantly branches of the cervical plexus
the cervical plexus is a somatic plexus considered
consisting of ventral primary rami of the first through the fourth cervical nerves
there's also a tiny contribution from c5 c5 comes from the brachial plexus
the brachial plexus consists of contributions of ventral primary rami of c5 c6 c7 c8 and t1
so you can see how the phrenic nerve is going to expand both of those plexuses the bulk of fibers
are coming from c4 so that roots this pretty solidly within the cervical plexus so the mnemonic
here to remember is c345 keeps the diaphragm alive and each phrenic nerve innervates a hemi diaphragm
so they're going to predominantly drive respiration now in terms of arterial supply
the dominant arterial supply is going to come from inferior to the diaphragm but there are
three arteries that will supply the diaphragm superiorly the main arteries are going to be the
superior phrenic arteries and these are direct branches of the abdominal i'm sorry the
the thoracic part of the descending aorta also pericardiacophrenic arteries these are branches of
internal thoracic artery that are going to accompany the phrenic nerves on the way down
and there will also be branches i mean while we're talking about internal thoracic
of the musculophrenic
arteries the musculophrenic arteries are those terminal branches of the internal thoracic
artery so the superior epigastric artery divides from the musculophrenic artery and
that musculophrenic artery as its name suggests will supply some blood to the superior surface
of the diaphragm now draining the superior surface of the diaphragm are the pericardiacophrenic veins
and the musculophrenic veins those are going to drain into the internal
thoracic veins posteriorly there may be a little bit of drainage through the azygos system
minor contributions and then the inferior surface supplies the bulk of the blood to the diaphragm
via the inferior phrenic arteries these inferior phrenic arteries supply the diaphragm inferiorly
and then in terms of veins there's a bit of an asymmetry here on the left side the left inferior
phrenic vein typically goes down and drains into the left renal vein as we'll see in that session
whereas on the right side the right inferior phrenic vein drains into the inferior vena
cava that left renal vein eventually drains into the inferior vena cava so all roads lead to rome
or in this case the inferior vena cava to conduct the blood back up to the right atrium of the heart
so we've discussed the structure of the diaphragm and its various apertures so the the cable
opening the esophageal hiatus as well as the aortitis and their contents we've discussed the
various neurovascular supply of the diaphragm including the phrenic nerves and the inferior
phrenic arteries among other vessels this is your summary slide thank you very much for your time