hello anatomy friends this is dr alsup and welcome to station number 11 where we are
going to talk about the anterior compartment of the forearm sometimes referred to as the flexor
compartment of the forearm because many of these muscles when they contract will either flex the
wrist or some of the digits of the hand so let's start with this anterior view we know
we're anterior we can see the polymer aponeurosis right here this is the palmar surface of the hand
and we are looking at a superficial dissection first and the first muscle i want to identify
is going to be the brachioradialis you can see here that i have an asterisk right next to it
and why do you think that is why do i have this as something we need to talk about a little bit more
well because conceptually when we discuss brachioradialis we typically talk about
it as being part of the posterior compartment or extensor compartment
and um that is mainly because it is innervated by the radial nerve whereas most of the nerves
or most of the muscles in this region in the anterior region are going to be innervated by
the median some by the ulnar but mostly by the median so usually this is discussed with the
posterior compartment because of its innervation but as you can see you can very clearly see
the brachioradialis from an anterior view it's taking up this whole lateral portion
of the anterior part of the forearm it's really not until you get into kind of this area on from
here that you are talking about the anterior compartment or flexor compartment of the forearm
recall though even though it is often discussed with the posterior compartment it does play a
role in terms of flexion weak flexion but flexion of the elbow joint so this is kind of that that
oddball but you can see it really well on this superficial dissection of the anterior forearm
okay next you can see right here that i'm outlining
the pronator teres so right here is the pronator teres muscle this is going to
be the most lateral of the superficial flexor compartment it is also going to not extend as
distally as the rest of these tendons because it is going to insert on the radius
and as its name would suggest it will play a role in terms of pronation of the forearm
next you have the flexor carpi radialis so i'm going to put an r right here for that one you can
see the muscle belly right here and then about mid in the middle of the forearm its muscle belly is
completely replaced by this long flattened tendon which is quite dominant in this superficial view
this next muscle right here we're not having you identify it has a almost the same length
of a tendon this is the palmaris longus it's not a very functionally important muscle so you don't
have to identify this one but i did want you to be aware of what that was and then the flexor
carpi ulnaris is going to be the most medial of these muscles it's so medial in fact we can't see
the muscle belly very well but you can see the tendon right there of the flexor carpi ulnaris
one muscle that you can see kind of peeking through here just deep to the palmaris longus and
the flexor carpi radialis is the flexor digitorum superficialis which you can see a little bit
better right here where the polymers longus has been cut so this is the flexor digitorum
superficialis oftentimes this is called a part of the intermediate layer it's the only muscle
in the intermediate layer but sometimes you hear it referred or lumped in with the superficial
layer because it does also have an attachment up here in terms of the medial epicondyle
so the flexor digitorum superficialis is just deep to the superficial layer in fact you can
see it from that superficial layer and it will have its tendons traveling through the carpal
tunnel the carpal tunnel is in this general region right here so the tendons are diving deep to this
region and then you can see them kind of popping out in this region heading towards the digits
deep to the flexor digitorum superficialis will be the flexor digitorum profundus which
is this whole muscle right here so you can see most of those uh superficial and
intermediate muscles have been removed in this particular dissection and you only see
the one muscle here which is flexor digitorum profundus
and again you will have these um these tendons that are traversing the carpal tunnel in this
region to head to the digits so you can see this is a really long or a really long muscle a very
flat muscle it will take up the whole space if you don't see any other muscles in the region you
know you're likely deep enough to in terms of the dissection to see the flexor digitorum profundus
and lastly the deepest muscle of the anterior part of the forearm and we
know we're still anterior because here's the interosseus membrane here and this muscle is
anterior to that this is the pronator quadratus but almost everything has to be removed in the
anterior compartment in order to get to the depth that you would need to get to
to find the pronator quadratus as its name would suggest suggests the muscle is going
to be quadrangular i almost think of it as like a little band-aid just above the wrist region
and again as its name would suggest it is going to be a powerful pronator of the forearm
all right excellent forearm muscles i think are some of the more difficult ones to identify
so take your time here find those ones that you still have some questions about
and please reach out with any specific questions and we'll work through it together thanks for your
time and attention here and we will talk the extensor carp compartment in the next station