hi let's talk about the associated structures to the lungs and ventilation pathway
these are structures which are very important to the session but don't neatly fold into any of the
other videos so let's begin with the sternal angle what we're looking at here is an osteological
structure called the sternum the sternum as you recall is tripartite there is a manubrium a body
and a xiphoid process and the sternal angle is this convexity that is anteriorly facing
that is between the manubrium and the body this is a palpable landmark recall that the second ribs
articulate at this point and they are setting up the thoracic plane
which runs posteriorly from this sternal angle back to the intervertebral disc between t4
and t5 that thoracic plane is going to separate superior mediastinum from the remainder of the
mediastina and will be in the vicinity of the tracheal bifurcation among other structures
the phrenic nerves come from the cervical plexus predominantly so they are rooted in ventral
primary rami of cervical nerves three four and five which five comes from the brachial plexus the
brunt of the phrenic nerve is coming from c4 however recall that in the root of the neck we
can see the phrenic nerve in close association with the anterior scalene muscle and then it
dives down into the thoracic inlet and is going to run between the lungs and the pericardium
so we can see the phrenic nerve here it's generally accompanied by branches of the internal
thoracic artery so the pericardiacophrenic artery as well as the pericardiacophrenic
veins which are draining into the internal thoracic vein we can see these phrenic nerves
here they are lateral to the vagus nerves which we can see coming down there and uh
it's the vagus nerve on the right is obscured here by the superior vena cava and bronchotracheal tree
but we can see the phrenic nerve there going down to the right hemidiaphragm
and the phrenic nerve there going down to the left hemidiaphragm
and that leads us to our final albeit major structure of lungs and ventilation pathway
the diaphragm the diaphragm is the muscular fibers sheet or just the muscle which is separating the
thoracic cavity superiorly from the abdominopelvic cavity inferiorly it has a very complex shape so
there is a right cupula then a left cupula which is less dramatic so there's the right
cupula and left cupula between the two is the central tendon of the diaphragm which is in very
close association with the pericardium surrounding the heart in profile here we have a nice view of
the right cupula as well as the left cupula and we can see the right and left phrenic nerves
descending down to serve those cupula so we've discussed the sternal angle the phrenic nerves
and the diaphragm which the phrenic nerves serve thank you very much for your time