Now let’s turn to the plantar aspects of the
foot and the plantar aponeurosis and its
various compartments. So what we see is if
you take away the skin of the foot, you have
a very tough membrane, the tough connective
tissue layer, and this is known as the plantar
aponeurosis. We can see it here. It’s thickened
within this central compartment of the foot,
just like the palmar aponeurosis in the hand.
So the deep fascia of the foot, it passes
down from the deep fascia of the leg. And
dorsally, we can’t see it here on the screen,
but it’s very thin and it’s continuous
with the extensor retinaculum. But on the
sole of the foot, the deep fascia is continuous
with the plantar fascia. And as I said, this
is thickened centrally as the toughened plantar
aponeurosis. This is really important.
This tough plantar aponeurosis, we can see it here.
This tough plantar aponeurosis, this triangular-shaped
thickening of aponeurosis, this plantar aponeurosis
protects the sole of the foot from injury.
As we’ll see later, it supports longitudinal
arches of the foot. So it helps to maintain
those arches and it helps to hold the bones of
the foot together. So it’s a really important
membrane, this plantar aponeurosis. So extending
from the calcaneus all the way towards the
digits, the plantar aponeurosis actually divides
into five bands. And these contain the flexor
tendons of the digits. At the level of the heads
of the metatarsals, the plantar aponeurosis,
as we can see here, is actually reinforced,
and it forms its ligament, which is known
as the superficial transverse metatarsal ligament.
And this helps to hold the metatarsals together.
Passing superior are intermuscular septa and these
divides the sole of the foot into compartments.
So the plantar aponeurosis is most inferiorly,
and then passing superiorly up through the
foot of a whole series of these intermuscular
septa, and they divide the foot into compartments,
a lateral, a medial, and a central compartment.
So we have the superficial transverse metatarsal
ligament helping to stabilize the metatarsals,
and also protect them as the forefoot bears
a great deal of weight. And then we have the
septa passing up that divide the foot into
compartments. If we look at the lateral, the
medial, and the central compartment, then
we see that these are covered by the plantar
fascia. So laterally, we can see here, associated
with the little toe, we’ll have the lateral
plantar fascia. And then medially, associated
with the great toe, we’ll have the medial
plantar fascia. Centrally, we have this thick
toughened band which is the plantar aponeurosis.
Compartments within the foot; there’s also
interosseous which contains the metatarsals
and the interossei, and the dorsal compartment
which we’ve spoken about before. So let’s
have a look at the muscles within the sole
of the foot and how they form these layers.
We have a whole series of muscles, and the
best way to describe them is by looking at
layers in which muscles form which layer.
So we can see we have layer 1 which is the most
superficial of the layer. We have a middle
layer which is layer 2 slightly deeper. And
then we have a deeper still layer, and that
is layer 3. So we’ve got consecutive dissections
revealing layers of the foot. So if we look