Hello anatomy colleagues this is Dr Alsup and in this video we will be discussing or identifying
the muscle compartments of the upper limb without the hand we'll leave that for a little bit later.
And this will be a superficial introduction as we will continue to build on details
of these muscle compartments such as name of the muscles, innervation, etc as we continue throughout
the curriculum but for today we are just going to get a basic spatial understanding of these named
compartments. And as we tend to do we will start proximally and move distally starting with the
shoulder region. The shoulder region does not have the typical type of muscle compartments that we
will discuss like in the arm and forearm which are separated by thick intramuscular septa or bone
but there are certainly muscles in this area including the deltoid muscle and the rotator
cuff muscles which are deeper and we're not going to see in this superficial view. We will be
locating the deltoid muscle in this session which is located in the superior portion of the shoulder
I often think of it as a cap on the top of the shoulder. It starts off wider and then it begins to
taper off to have a distal attachment around the midpoint a little bit above the midpoint of the
humerus or the midshaft of the humerus. You will see that the deltoid muscle is dominant in both
this anterior view as well as a posterior view, this is the deltoid muscle here you can see a few
of those rotator cuff muscles right here. So the deltoid is a very thick and coarsely fibered
muscle, so hard to miss even in individuals that do not have particularly robust deltoid muscles.
Moving to the arm, there are two compartments of the arm and they are very well named.
There is an anterior compartment
which as its name would suggest is located anterior to the humerus
and a posterior compartment which is located posterior to the humerus.
There are less muscles in the compartments of the arm than what we will see in the forearm
and they tend to be larger muscles particularly when discussing the posterior compartment
which is dominantly occupied by the triceps brachii muscle, which you can see very clearly here.
When looking at a superficial view of the anterior arm the biceps brachii is the muscle that's most
easily observable because it's superficial and you can see the two heads or the two tendons
of the biceps brachii or proximal tendons. Lastly let's discuss the compartments of the
forearm which like the arm there is an anterior compartment and a posterior compartment separated
by the radius, ulna, interosseous membrane which is the joint connecting the two bones,
and the intermuscular septa. And there are considerably more muscles in the forearm than
what we have in the arm and this is visible from even looking at a superficial view which is what
we are looking at here for both the anterior and posterior. There are even more muscles in
these compartments the deeper you get within the compartments. I can usually pretty quickly
tell if I'm looking at an anterior posterior view for a few reasons. So starting anteriorly
this is the palmar or anterior surface of the hand and I can tell because you have the palmar
aponeurosis right here, you have more muscles that are visible, this large thenar compartment and
hypothenar compartment so all signs are pointing towards this being the palmer or anterior surface.
Additionally if you look at this proximal portion of the image you can see a depression here with a
lot of neurovasculature. This is going to be a region called the cubital fossa and if you look at
your own anterior portion of the elbow region you will notice that there's a depression right there
and so that is this region right here, all signs leading to this region being the
anterior compartment of the forearm. We'll get to this interesting muscle right here in the in the
sessions where we actually discuss the muscles but this actually is often considered part of
the posterior compartment. So most of the anterior compartment of the forearm is more medially placed,
and I know that's medial because first digit is always lateral, fifth digit is going to be medial.
Looking posteriorly the major thing I notice is that the olecranon is right here
which is the point of the elbow if you feel the back of your own elbow region
that is what you are feeling that bump and this is where that triceps brachii
muscle tendon is going to insert and so I know that i'm looking at a more posterior view.
So more to come regarding these muscle names but for now I just wanted to look at them
and begin developing strategies for understanding basic positioning. Alright excellent thank you
all for your time and attention here, and please always feel free to reach out with any questions