The diaphragm may also be appreciated with
simple imaging, for example, a radiograph.
And again, we’ll be able to appreciate the
fact that the right dome of the diaphragm
does sit at a higher level than the left dome.
There is a little bit of interpretation work
that one kind of has to master in order to
understand where some of these structures
may lie, but the right dome of the diaphragm
is right along this margin here. The left
dome is seen here and the left dome again
is sitting at a lower level than the right
Now, there can be situations that may cause
either the right hemidiaphragm or the right
dome to be much higher than normal. Similarly,
there could be an effect just on the left
side where the left hemidiaphragm or the left
dome becomes situated at a much higher level.
And some of the causes of having an elevated
hemidiaphragm, keep in mind that this radiograph
is the one we saw before, it is normal. But,
if you had a decreased lung volume, for example,
if you had a pneumothorax within the right
pleural cavity, the right lung would collapse,
thereby allowing the right hemidiaphragm to
ascend at a much higher level.
You could have phrenic nerve palsy either
on the right phrenic nerve or on the left
phrenic nerve. A common entity or a common
ideology here for phrenic nerve palsy would
be lung cancer that’s invading and involving
the phrenic nerve. So, if it’s the right
phrenic nerve, you would have an elevated
right hemidiaphragm. If it’s involving the
left phrenic nerve, it would be the left hemidiaphragm
that would be elevated.
A contralateral stroke to the motor neurones
that are conveyed throughout the phrenic nerve,
if it’s on the left side, that would cause
contralateral elevation of the right hemidiaphragm.
You could have an abdominal tumour and so,
you could have this growing tumour pushing
upwards against the diaphragm and causing
an elevation. And there are some other causes
The diaphragm, as mentioned earlier, does
have a central tendon. And we see the central
tendon in this area here. And then we see
the striated muscle fibres that make up the
diaphragm that are more peripherally located.
And they extend all the way along the movement
of the cursor here.
We can divide these muscular parts into a
sternal part of the diaphragm. We also have
a more extensive part of the diaphragm with
attachments to the ribs. And this more extensive
part of the diaphragm would be the costal
part. And then we also have lumbar components
here to the diaphragm. And we see those contributions
in through here.
If we take a look on this side, we have some
more geometry anatomically. And we see the
same geometric configuration on the opposite
side of the diaphragm.
This is the lumbocostal triangle, also referred
to as Bochdalek's triangle. The diaphragm
doesn’t develop appropriately during foetal
life, embryonic life. There can be a defect
and it’s usually on the left side in the
area of Bochdalek's triangle. And this defect
would allow herniation of abdominal contents.
And again, it’s usually on the left up into
the thoracic cavity where the lung is situated.
And that would then result in developmental
defects with the lung.