Hello anatomy colleagues this is Dr Alsup and in this video we will be discussing how
to identify the neurovasculature you need to know for the forearm, wrist, and hand session.
So recall that the artery of the arm that I'm outlining right here is going to be the brachial
artery and we located this in the last session. And the brachial artery will enter the cubital
fossa which is in this general area right here and it will divide into its two terminal branches.
So the more lateral is going to be the radial artery which I'm outlining
in green right here it will continue on into this region so this is the radial artery and so it's
running down the flexor digitorum superficialis here it's heading towards the anatomical snuff
box over here posterolaterally and the other terminal branch is going to be the
the ulnar artery we can only see a little bit of that right here.
And the reason we can only see that here even though it's the major supplier of the forearm
it's going to dive deep and we only see a small portion until we get a much deeper dissection
like we have here. So in this much deeper dissection we have and I can tell this because
we have the ulna over here you can see a bit of the radius here and the interosseous membrane
that's connecting the bodies of the ulna and the radius so we know we're pretty darn deep here.
And these are the same arteries that we saw in the last
image but now we're just a little bit deeper so here's the brachial artery
and then over here, let me change the color
now I'll get a little bit faster at doing this, over here will be the radial artery
and then the where we can really start seeing the ulnar artery is in this deeper dissection. Again
I mentioned that the ulnar artery is a prominent supplier of the forearm. It will continue medially
all the way down here until it gets to the hand
but you can also see that it gives off branches kind of throughout this region of the forearm,
so it's really important in terms of supplying the forearm. You can also see a special guest a
special nerve guest in this image with the ulnar artery so you can see it here you can see it's
behind or posterior to the medial epicondyle which is right here and it will traverse very closely
to that neighboring ulnar artery I really should have the artery be red but this is going to be
the ulnar nerve and then in green here that will be the ulnar artery.
Neither the radial or the ulnar arteries travel through the carpal tunnel
but they most certainly make their ways to the hand and they stay in the positions that they
should. So the radial artery you can see here is going to be lateral and I know this is lateral
because this is the first digit this is the fifth digit, the fifth digit is the most medial.
And so that means that over here you can see the ulnar artery is going to be the medial one.
There are two palmar arterial arches in the hand so these are basically arches of arteries that
get a bunch of branches from different areas and both the radial and the ulnar arteries will send
contributions to both of these palmar arterial arches but one of the arteries will always be
the predominant supply. So for this right here this region right here which is the superficial
palmar arch SPA I never really realized it has that cool
abbreviation there, but so SPA the superficial palmar arch its dominant supply will be the
ulnar artery with small branches from the radial artery. In the deep palmar arch not pictured here
the radial artery will be the dominant supply with a small supply from the ulnar artery.
Now let's turn our attention to some nerves, and now what is this thing I keep saying
about the radial nerve there's something i keep saying over and over again, oh yes
of course it's "radial nerve equals posterior" meaning the radial nerve supplies or is the motor
innervation for the posterior compartments of the arm and the forearm. And we know that the radial
nerve is a terminal branch in fact the largest terminal branch of the brachial plexus and you
can see the radial nerve here in this very classic position near the radial groove of the humerus so
you can see the humerus here. The radial groove of the humerus is on the posterior side of the
shaft or the body of the humerus and the radial nerve travels in very close proximity in fact it
creates a little groove in the bone there, and this is deep to the triceps brachii which is
right here. Fractures of the radial groove region can affect this neighboring radial nerve.
The median nerve is another terminal branch of the brachial plexus and is the dominant
motor supply for anterior forearm muscles and a few muscles in the hand.
You can see in this cubital fossa it is located, I'm going to draw kind of little leader lines so
these are both the median nerve, so it's going to be traveling
neighboring the brachial artery as well as the ulnar artery and some of the veins right here
and so it will be on the more medial side of that vasculature this is medial because here's
your fifth digit see how I always do that that always kind of keeps me grounded there.
But that median nerve will dive deep because it's going to supply these muscles in the or
most of these muscles in the anterior compartment of the forearm. Here we are looking at a posterior
view of the forearm and this is a deeper dissection I can see part of the ulna here
that superficial layer has been removed and we can see and I'm just going to circle it
right here we can see some branches of the radial nerve and this these specific branches
are called the deep branch of the radial nerve which is efferent and will innervate the muscles
in the posterior compartment. So this will be one of the branches of the radial nerve
but we're in this posterior compartment so it makes sense that any of these branches around
here would be from the radial nerve. Lastly in the hand the two dominant nerves are the median
and the ulnar nerve, you can see a bit of the radial nerve right in this region here.
And the radial nerve will provide some cutaneous innervation to small portions of the hand but it's
really the median and the ulnar nerve that are the major nerves associated with the hand and
of the two the ulnar nerve will be the dominant efferent or motor supply for muscles of the hand.
So almost everything almost every intrinsic hand muscle except for the thenar compartment
and a few lumbricals and it will also certainly provide cutaneous or afferent innervation.
You can see the ulnar nerve entering the hand medial and superficial
to the carpal tunnel so the carpal tunnel this is the roof of the carpal tunnel right here
and you can see that the ulnar nerve is coming kind of over that so it does not not not not
traverse the carpal tunnel the ulnar nerve does not. You can see that once it gets to the hand
it begins to send branches everywhere and that makes sense because it has a lot to supply there
and you can see it really nicely here in this kind of close-up view
so this is our ulnar nerve. Now over here you can so this is the again this is the roof
of the carpal tunnel and so the median nerve does traverse the carpal tunnel so that median nerve
is going to be deep to this ligament that's creating the roof of the carpal tunnel called
the transverse carpal ligament or flexor retinaculum we'll talk more about that
in the carpal tunnel video. But the key is that the median nerve does traverse the carpal tunnel. It
provides a small efferent or motor branch called the recurrent branch
of the median nerve to the thenar compartment you can see a little peek of it right there
right there in that thenar compartment and it also has numerous cutaneous branches throughout
the hand. Excellent so that is a review of the neurovasculature we need to identify
in this session. Please take time to review and I hope you have a great rest of your day