Muscles of the Foot Part 1 – 3D Anatomy Tutorial

Muscles of the Foot Part 1 – 3D Anatomy Tutorial


Okay, this tutorial is on the intrinsic muscles
of the foot. So the intrinsic muscles are those muscles which originate and insert in
the foot. So these muscles act to produce the fine movements of the toes and they also
support the arches of the foot. The relationship between some of the intrinsic
muscles with the tendons of the leg muscles which enter the foot means that these muscles
can actually change the way that the forces are produced by some of these muscles and
we’ll look at that in a bit more detail. So just like the other groups of muscles that
I’ve talked about, the intrinsic muscles of the foot can be separated into different layers.
So you’ve got a plantar group and a dorsal group. The dorsal group is really simple because
there’s actually just one muscle in this group, but the plantar group has four different layers.
So I’ll talk you through those. Just before I start, just a quick mention
about the innervation of the foot muscles. Apart from the extensor digitorum brevis and
the first two dorsal interosseous muscles, all the intrinsic muscles are innervated by
branches of the tibial nerve. So we’ve got two branches, the medial and lateral plantar
branches. I’ll just bring in the nerves and we’ll take a look at those quickly. We’re looking posteriorly at the distal leg
and foot. You can see the tibial nerve running medially behind the middle malleolus and entering
onto the flexor retinaculum to enter the tarsal tunnel. So I’ll just fade away the muscles
we can have a look at this nerve. I’m just showing you the plantar surface of
the foot. You can see the tibial nerve running medially in the distal foot and it enters
the plantar surface of the foot and it splits into these two branches. So laterally, you’ve
got the lateral plantar nerve and medially, we’ve got the medial plantar nerve. So these
two branches for the tibial nerve are responsible for innervation of the majority of the intrinsic
muscles of the foot. So the extensor digitorum brevis muscle is
innervated by the deep fibular nerve. So this is this nerve here which runs anteriorly on
the tibia. It also supports and innervates the anterior muscles of the leg. So this branch,
this nerve, the deep fibular nerve innervates the extensor digitorum brevis muscle and the
first two dorsal interosseous muscles, but all the other intrinsic muscles are innervated
by the medial and lateral plantar nerves, which are branches of the tibial nerve. So in the dorsal group, you only have one
muscle and that’s the extensor digitorum brevis muscle. I’ll just quickly show you that. I’ve just isolated the extensor digitorum
brevis muscle and you may notice that there’s this other label here, which says extensor
hallucis brevis. This is what the software has brought up, but this muscle is actually
often considered part of the extensor digitorum brevis muscle. I’m just going to talk about
the extensor digitorum brevis as it includes the extensor hallucis brevis. So I’ve removed all the other muscles, so
we can take a closer look at this. Just looking at its origin, you can see it originates superiorly
and laterally on the calcaneus. And if we look at the insertion, we can see the first
tendon of the extensor digitorum brevis inserts at the base of the proximal phalanx. And if I bring the rest of the muscles in,
we can see the insertion point of the other three tendons. You can see that they insert
laterally on these tendons. So these are the tendons of the extensor digitorum longus muscle.
So the extensor digitorum brevis muscle inserts laterally on these tendons. These three toes
here, the extensor digitorum brevis inserts laterally on the tendons of the extensor digitorum
longus muscle. So you must notice that there’s no tendon
coming from the extensor digitorum brevis muscle to the little toe. It’s just the medial
four toes that there are tendons to. So this muscle extends the MPT joint, but
it’s innervated by the deep fibular nerve.