So we're talking about the lower limb muscles particular to the leg and these muscles are very
different depending on if you're looking at the anterior portion or the posterior portion so let's
start with the anterior compartment of the leg and before we get into the actual muscles I want
to talk about how these muscles are very tightly bound within the connective tissue here so if you
have any blood or fluid that's going to escape it's not going to get very far it's going to get
trapped within the compartment so have you ever heard of the term compartment syndrome typically
they're talking about in the specific compartment so there's three main muscles in this region I'm
not going to have you memorize the particular muscles but I want you to understand at least
the actions that can occur with contraction of these muscles so importantly you're gonna have
dorsiflexion of the ankle so remember dorsiflexion those toes are going to be pointing up extension
of the digits so those tendons are going to allow for the the digits remember this would be flexion
extensions going to be coming out so when you're just standing normally and then inversion of the
foot so in particular if you're looking here here is your tibia all of these anterior compartment
muscles are going to be on the lateral side right here and the largest one right here
is your tibialis anterior any muscle that starts with tibialis is going to play a role in terms of
inversion of the foot all of these muscles are going to be efferently or motor innervated by the
deep fibular nerve and the deep fibular nerve is going to be a branch of your common fibular
nerve and the common fibular nerve is one of the terminal branches of your sciatic so say
you do have some type of escape in terms of the fluids that can occur within these this area this
can cause for your tibialis anterior to really be smashed down so that can cause some issues
there also if you continuously use your tibilalis anterior this can allow for little micro tears
within the muscle that can actually affect the periosteum of the tibia here so if you've ever
heard the term shin splints is typically having something to do with your tibialis anterior now
on the lateral compartment of the leg these are going to be composed of two muscles your
fibularis longus and brevis and longus is going to be the more important of the two and you can
see right here only in this view you have your fibularis longus the brevis is going to be deep
to this muscle so this is going to be innervated by the other branch of the common fibular your
superficial fibular nerve and you can actually see right here in this image your common fibular and
that superficial the split of the superficial and deep is going to be right underneath your
fibularis longus muscle so remember the tibialis muscles are going to play a role in terms of
inversion of the foot so the fibularis muscles are going to be eversion of the foot so allowing for
the sole of the foot to move more laterally also they're going to play a very very weak role in
terms of plantarflexion all right so let's move posteriorly now and you have two compartments
associated with the posterior side you're going to have a superficial which is what we're looking at
here and this is by far the more substantial and the more important of the two compartments and
you're gonna have a deep which we'll just discuss in just a moment so the superficial compartment is
composed of two muscles your gastrocnemius or gastrocnemius you'll hear it either way and
your soleus muscle which is going to be deep to the gastrocnemius so you can see here when you
think of your calf muscles these are the two muscles that you're thinking of gastrocnemius
is going to be the more superficial and soleus will be deep to these two muscles or to this
area now what's important is you're going to have these two muscles they're going to kind of come
together in terms of their distal attachment and they're going to share one tendon and that's your
calcaneal tendon and we've all heard of your calcaneal tendon referred to as your Achilles
tendon this is these strongest tendon in the body if you have damage to your calcaneal tendon that
can really play have devastating effects in terms of being able to plantarflex the foot or even to
simply be able to walk because plantar flexion is going to play a role there this these muscles are
going to be innervated by the tibial nerve which is one of the terminal branches of the sciatic
plantar flexion this is hugely important here so these are the main plantar flexors of the ankle
also that gastrocnemius if you can see here and you can see a little bit you can see that it's
extending past the knee joint region so it can play a role in terms of flexion of the knee now if
you were to reflect these muscles out of the way then you would be looking at the deep posterior
compartment of the leg similarly innervated by the tibial nerve which you can actually see in
this visual here so it kind of sits on top and since muscular branches to these these are also
going to play a role in terms of plantar flexion of the ankle however it is such a minor role that
say something did happen in terms of the calcaneal tendon or in terms of just the gastocnemius muscle
or the soleus muscle these could not compensate for that particular action certain muscles within
this compartment will also play a role in terms of flexion of the digits so think about curling
your toes as well as inversion of the foot because you have in here your tibialis posterior muscle
so tibialis you know we're talking inversion of the foot so these these muscles as you can
see they're going to extend into the foot so the tendons are actually extending so they can
play a role in terms of the digits or in terms of the subtalar and transverse tarsal joints