00:01
the posterior compartment are also supplied
by the tibial nerve. So if we look at the
anatomy of these, then we can see in greater
detail the nice fleshy gastrocnemius. We can
see the lateral head here. And then from the
medial aspect of the lateral head, we can
see plantaris. And here, we’ve got the medial
head. Remember, it’s this lateral surface
of the medial head, and the medial surface
of the lateral head that forms the inferior
boundary of the popliteal fossa. We can then
look at this diagram and see the fleshy soleus
and we can see the long tendon of plantaris. So the
posterior compartment evolved in plantarflexion
allowing you to stand on tiptoes. The superficial
layer, gastrocnemius, soleus, and plantaris,
are innervated by the tibial nerve and supplied
by the posterior tibial artery and some fibular
vessels which run within the deep layer. The
two heads of gastrocnemius and soleus, together,
are known as the triceps surae. This is responsible
for elevating the heel, and therefore, depressing
the forefoot. And this is what happens when
you stand on your tiptoes. You elevate the
heel and you depress the forefoot, the front
part of your foot. These three muscles really,
the two heads of gastrocnemius and the soleus,
known as the triceps surae form the calcaneal
tendon. And within the calcaneal tendon, the
fibres of gastrocnemius and soleus rotate,
so that gastrocnemius is actually lateral
and soleus is medial within the calcaneal
tendon. And this increases the elastic property
of the tendon, and therefore, its ability
to recoil really important features in being
able to plantarflex. Plantaris is a small
muscle with a long tendon. It has a very small
muscle belly, and the tendon, as we can see,
runs in between soleus and gastrocnemius.
If we look at the deep layer of the posterior
compartment, and we can see here the muscles
have been reflected. So here, we can see we’ve
got soleus that’s been reflected, popliteus
has been reflected. Then we can see these
muscles passing down here. We have tibialis
posterior here in a slightly deep dissection.
02:17
Most superficially, we can see flexor digitorum
longus here. And coming out from quite deep,
we have flexor hallucis longus here. And these
are giving their tendons that pass posterior
to the medial malleolus. We can see that in
this diagram here. So if we look at the deep
layer, including popliteus, flexor digitorum
longus, flexor hallucis longus, and tibialis
posterior, they were all innervated by the
tibial nerve and they’re supplied by the
posterior tibial artery and fibular vessels.
We can see them all lined up here, fibularis,
flexor digitorum longus, tibialis posterior,
and flexor hallucis longus. We can see
them here. And their tendons, as we can see them
passing down here, are running posterior to
the medial malleolus. We can see they’re
also enclosed via this flexor retinaculum,
which is running from the medial malleolus
to the calcaneus. We can see these tendons
passing to the sole of the foot. The three
long tendons or flexor digitorum longus, flexor
hallucis longus, and tibialis posterior pass
posterior to the medial malleolus, from medial
to lateral. So here, if we have a look, we
can see we have the medial aspect of the foot
and the lower leg here. Here, we’ve got
the lateral aspect. And if we go from medial
to lateral, so if we go from medial to lateral,
we see we have the tendon of tibialis posterior.
04:01
We’d see the tendon of tibialis posterior
here. Then moving laterally, we have the tendon
of flexor digitorum longus. And then if we
move laterally again, we have flexor hallucis
longus. So from medial to lateral, we have
tibialis posterior, flexor digitorum longus,
and flexor hallucis longus. And this is at
the level of the medial malleolus. So it’s
posterior to the medial malleolus. Here, we
can see it at the ankle joint, we can see
medial malleolus here, then we have tibialis
posterior, we have flexor digitorum longus,
and then we have flexor hallucis longus. And
these are now passing to enter into the foot.
04:45
In this region, we also have the posterior
tibial artery and the tibial nerve passing
into the sole of the foot. Flexor hallucis
is particularly important as it provides the
final push for elevation of the foot, after plantarflexion
has been initiated by the triceps surae.
05:05
So the triceps are important in elevating
the heel, depressing the forefoot. But the
final push off is by the great toe carried
out by flexor hallucis longus. It’s a very
important muscle. So in this lecture, we started
off by looking at the deep fascia of the leg
and the intermuscular septae in the cross-section
of the leg. We then looked at the anterior
compartment. We looked at the muscles like
tibialis anterior, extensor hallucis longus,
extensor digitorum longus, and fibularis tertius.
We looked at the extensor retinacula. We then
looked at their function and innervation.
We then moved onto the lateral compartment,
looking at fibularis longus and brevis, their
relationship to the lateral malleolus and
the fibular retinacula, and also their function
and innervation. And then finally, we looked
at the posterior compartment, the muscles
in the deep and superficial layers, and the
relationship of those deep muscles to the
medial malleolus. We looked at the triceps
surae and the formation of the calcaneal tendon.
We finally, and throughout the
lecture, looked at their function and innervation.