-: Okay, so when we're talking about plantar flexion
as a whole motion, these are drawn on here.
The primary muscles that are involved
in taking that ankle joint and pointing it
as much as possible.
So the biggest guys here most obviously
in green are gonna be the gastroc, okay.
Gastroc medial head and then the gastroc lateral head.
And they basically come in and fuse together
into this Achilles tendon which attaches down
into the calcaneus down here.
Now cross here on the other side, these guys
will come up here and almost sneak underneath the hamstrings
into the the medial condyle and the lateral condyle
of the femur, okay.
And because of this unique attachment
they're actually, this is considered a biarticular muscle.
So they're going to play an important role
in knee stability from like a, like a gate standpoint
every time you take a step and walk
but also they're going to add to knee flexion.
They'll be one of the initiators,
the primary initiators of knee flexion
and also one of the primary plantar flexors of the foot.
So they do quite a lot.
Underneath that, so deep to that, we have this guy in red
which I've also kind of dotted an outline up here.
So it attaches a lot higher than it seems.
That's your soleus.
And the soleus has a medial and a lateral head as well.
And it also creates plantar flexion and it fuses
into the same Achilles tendon as the gastrocnemius does.
So they both kind of help each other out.
Lateral to that we have flexor hallucis longus,
which comes from the big toe and wraps all the way around.
And then it comes up and attaches at the lateral fibula
and then opposite that on this side.
So let's have you turn just a little bit this way.
Okay, opposite that on this side,
we've got the flexor, flexor digitorum longus here,
which attaches directly to the, the posterior tibia as well.
And that wraps underneath the entire foot.
And then we've got, it attaches
to the tips of the phalanges there.
So towards the lateral side of the foot
we have the peroneus brevis,
which comes lateral to the fibula.
So this could also be considered the fibularis brevis.
Comes out here and it attaches into the fifth,
the tip of the fifth metatarsal.
So that's also gonna create plantar flexion
and also it's going to be a primary like
pronator of the foot.
And then we have this fibularis longus
which has the highest attachment,
comes down and across and wraps all the way
underneath the foot, having two attachments,
one attaching to the cuboid bone and also attaching
to the bottom of the first metatarsal.
So if we look on the foot here
we're gonna see that we've got a long attachment
across the fibula coming all the way around.
And it wraps around the bottom of the foot,
attaching at these two bones here,
which is the first metatarsal
and also the, the cuboid bone right here.
So it creates kind of this, it kind of helps
to like we talked about with dorsiflexion,
cinching up the bones of the bottom of the foot,
adding a tremendous amount of stability
so that the rest of these guys can do their job.
So hopefully you can see that even though we have
such an obvious muscle here that is a primary motion,
primary for plantar flexing the foot,
we also have a lot of these other muscles
that create kind of this like corset that wraps up
underneath all of the forefoot bones in order
to be that stability so that the rest of these guys
can do their job properly.
Okay, so as far as going over the motion of the ankle,
it's not just plantar flexion in the exact sagittal plane,
because you've got two joints here
that actually have to move through whatever range
gets them to a maximally shortened position
for these tissues.
So really what it's gonna be is, once it gets to this point
you're gonna see some supination deviation
in order to complete that motion here.
Just relax for me, Chelsea.
Right? So we're gonna see that once it gets here
that's not the end, it actually deviates in.
And so you're gonna see things move
kind of in this axis of motion right here.
Now, one thing that's interesting
is if you supinate too soon
you're actually gonna get less plantar flexion out of it.
So really the order of operations is important.
It's gonna be full plantar flexion
with that final deviation.
And because of the structure of this joint,
most of us assume just because we know maybe a little bit
about engineering, that it's actually like a straight axis.
Like there's like a, as if there was a pin
through this joint and it spins on its own axis.
But because of the shape of this bone,
we're actually gonna see that the axis kind of moves
as it kind of moves all the way around to its end range.
And so what you're gonna notice is that as it starts here
in, in like relative dorsiflexion,
the part of the foot here is facing up
and as it kind of comes around right,
once we get to that fully plantar flex position,
the foot is facing completely in this direction.
So what that means is that most calf raises,
they're only going to allow you to exert
a good amount of pressure up until about here.
So a real calf raise would actually allow you
to continue to push back that way.
So it would be back behind you
rather than down into the floor, okay.
I don't know too many calf raises that allow for that
but there are some modifications that can be done
and that will actually help you to work plantar flexion
through its fullest active range.
Okay, one other muscle that I have not drawn on here.
And the reason I have not drawn on here
is because it's very deep to the rest of these tissues
and that's called your posterior tibialis muscle.
And that guy runs in between these two bones, like very deep
and it actually wraps around the front
and it spreads out like a hand and it attaches
to all the cuneiforms
and these middle three metatarsal bones, okay.
And it is one of the most important muscles
for stabilizing the forefoot.
And as I've talked about, the stability of the forefoot
is going to determine how much ultimate motion
you can get outta the prime movers of the entire ankle.
So one assumption that's made is that the muscles
on the front of the, the shin attaching
to the top of the foot are what's responsible
for keeping that arch stable and steady under load,
but really because of the mechanics
and the way that the arch of the foot is structured,
a downward pull from this very important muscle
called the posterior tibialis is what's actually
going to create the stability necessary
to keep your arch nice and high and stable
and all this really stable in order
for the rest of these guys to do their job better.
So posterior tibialis is one of the more important
stabilizer muscles in the foot.
That's as about as deep as it gets.