Hello anatomy colleagues this is Dr Alsup and in this video we will be discussing the lateral
compartment of the leg. And this is a smaller compartment so this will be a shorter video
but we will be covering the similar players which of course are the muscles the actions
they play a role in as well as innervation. Excuse me, all right so again the lateral
compartment is the smallest or the narrowest compartment of the leg. In fact when looking at
a directly lateral view which you can see here we can see the two muscles of the lateral compartment.
These are going to be the fibularis or peroneus longus as well as the fibularis or peroneus brevis,
peroneus you see a lot of times replacing the term fibularis. But as you can see you can
have other compartments or other muscles of other compartments as well so you can see the tibialis
anterior as well as the extensor digitorum longus muscle from the anterior compartment
as well as the soleus and the gastrocnemius which is not labeled here but these two are
going to be part of the posterior compartment. So all this to say that you just have this relatively
small region right here that is going to make up the lateral compartment. The fibularis longus
as its name would suggest is longer and it's more superficial as well so it's going to become more
tendoness you can see it kind of narrowing down to this tendon right here as you get more distally.
The fibularis or peroneus brevis is shorter and deeper but it's often visible right where
the fibularis longest tendon is so you can see the fibularis brevis
deep to the fibularis longus tendon.
The primary action of the lateral compartment is eversion so we have the e here the e version of
the subtalar and transverse tarsal joints and this is going to move the sole of the
foot or the plantar surface laterally so in essence it's elevating the lateral margin
of the foot. And this makes sense because I hope at this point that you can understand if we're
talking about fibularis muscles or peroneus muscles that fibularis muscles evert whereas
tibialis muscles invert so inversion is moving the sole of the foot more medially.
The fibularis longus and brevis also play a weak role in plantar
flexion or lifting the heel up and the toes down such as when one stands on
their toes but again I want to emphasize this is a weak roll
it's that posterior compartment of the leg that's going to play the biggest role in plantar flexion.
Lastly this compartment is entirely innervated by the superficial fibular or peroneal nerve which is
one of the terminal branches of the common fibular or peroneal nerve and you can see in this image
here the common fibular nerve coming down from the popliteal fossa, it will wrap around the neck
of the fibula in a fairly subcutaneous location so less protected right around this region here,
to direct trauma in that region because it's right up against the bone and it's
fairly subcutaneous there. But that common fibular peroneal will give off the superficial fibular
which will supply this lateral compartment and the deep fibular peroneal nerve which supplies
the anterior compartment of the leg. Excellent we have arrived at the summary slide which is
short and sweet which makes sense for a fairly small muscle compartment. Please take time to
review and always feel free to reach out with any questions. Have a great rest of your day