00:00
also flex the fifth digit. So if we now move
on to layer 2, we can see that we’ve had
flexor digitorum brevis removed. Abductor
digiti minimi is still present, and abductor
hallucis is still present. But really, layer
2 is concerned with this arrangement of muscles
in this central compartment. So we have quadratus
plantae and we have lumbricals. And these
are really important. If we look at quadratus
plantae, we can see that’s running forwards
and it’s actually inserting into the tendon
of flexor digitorum longus. So a contraction
of this muscle is going to support flexor
digitorum longus. It may as well straighten
the tendons so the line of pull is more efficient.
Then we have the lumbricals, and we have four
of these lumbricals. And they’re similar
to lumbricals we observed in the hand.
00:56
They’re originating from the tendons of flexor digitorum
longus as well. So if we look at quadratus
plantae, we see it comes from the medial and
lateral aspect of the calcaneus, and it inserts
into the lateral margin of the tendons of
flexor digitorum longus. It’s supplied by
the lateral plantar nerve. And as I mentioned,
this muscle is important in flexing or assisting
the flexion of digits 2 to 5 with flexor digitorum
longus. The lumbricals, just like the lumbricals
in the hand, are coming from the tendons of
flexor digitorum longus. And they insert into
the medial aspect of digits 2 to 5. So they
pass from the tendons of FDL to the medial
aspect of the digits 2 to 5. Their nerve supply
is different. The medial lumbricals are supplied
by the medial plantar nerve, and the two lateral
lumbricals are supplied by the lateral plantar nerve.
01:58
So the medial two lumbricals are supplied
by the medial plantar nerve and the lateral
two lumbricals by the lateral plantar nerve.
These muscles have an important function.
02:08
They are important in flexing the proximal
phalanges and extending the middle and distal
phalanges of digits 2 to 5. So it’s very
similar function to the lumbricals in
the hand. Now let’s move on to layer 3, which
contains a few more muscles. We’re going