-: Okay, so as far as the anatomy
of the primary muscles of hip flexion,
the main guy that we wanna pay the most attention
to is going to be the psoas major,
the psoas major connects
and it, it actually originates at the lumbar vertebra
and also at the top,
like T-12 bottom thoracic vertebra.
And the fascia from here continues up
and fuses along with the fibers of the diaphragm
which runs along the entire inside of the ribcage.
So, this has a tremendous ability to create stability
through the trunk and transfers a lot
of those forces from the hip up and through the spine.
So, it's that one of the main links
between the spine and the hip.
As this comes down
onto the femur, you've got this little attachment here
it's this little bump that's known as the lesser trochanter
And it comes on in, and it attaches right there
and fuses with a common tendon that belongs
to a muscle known as the iliacus
and the iliacus originates on the inside of this
entire iliac crest, so it kind of fills in this entire gap.
So, that's why this whole complex here
is known as the iliopsoas
but really it's the iliacus and the psoas major.
Additionally, we have on the lateral side here
there's something called the TFL.
So if we turn a little bit this way,
the TFL is a small muscle belly
but it attaches into this kind of fibrous
like tenderness structure that's known
as the IT band or the iliotibial tract,
and that comes all the way down
crosses the knee and inserts at the tibia
at the tibial tubercle.
There are other muscles that assist
in promoting hip flexion.
So, primarily you've got on this side in blue
you've got the rectus femoris, which is a quadriceps
but that one is only going to be able to shorten
to the degree where, about 90 degrees
it's going to help to assist you into
and then you've got your entire adductor complex
on this side, which includes the pectineus
the adductor longus, the adductor brevis
and even the gracilis.
And each one of these are going to help with hip flexion
but up to a certain degree and maximum probably
the pectineus is the one that can, has the
the greatest degree of the ability to help with hip flexion,
but that one will probably start to taper off
in its ability to help maybe at about 75 to 80 degrees
of hip flexion.
So in reality, when it comes down to it, that psoas majors
and the iliacus are gonna be the only real
hip flexors that are going to have a good amount
of control of hip flexion above 90.
So we'll start to see,
if Chelsea can kind of bend her knee and bring her hip up.
This is where the psoas major is going to start to
have a better line of pull.
And if you start to pull up even higher, this is where that
psoas major is going to help in the,
the greatest capacity for hip flexion.
The hip flexor, being the muscle that gets the shortest
into the greatest amount of hip flexion for the hip,
will actually bring us into a position of slight abduction
as we get all the way through that hip motion.
And the reason why is because this hip,
in most people is going to have some degree
of an angle that kind of angles outward,
which means that as we bring Chelsea's leg
to full hip flexion, it's going to have to abduct slightly
into a slight external rotation relatively
in order to complete that back and forth communication
with the glute max.
So, there is a synergy between the hip flexor
and its greatest range of motion
and the glute max and its direct opposing motion.
So, hip flexion all the way is gonna end up here
with slight abduction, and it's gonna come slightly out
which is gonna pull a full stretch on that glute max
and then moving into full hip extension.
We're gonna end up seeing slight abduction
and full hip extension, which is gonna conversely
put a full stretch on the tissues of the psoas major.
-: So when we look at the function
of the hip and we look at the motion
that's gonna be required to get to full hip flexion,
it's going to be similar to hip extension
and it's not gonna be this straight kind of, you know
forward and backward motion because the pelvis
doesn't function like, as a block
with a pivot point that goes front and back
for the hip to be able to flex and extend.
There has to be this kind of arching motion
because of not only the shape of the pelvis here,
whereas if, as we start to get more flexed, the tissues
the adductors and everything will actually start to come
up and impinge at a certain point.
And then we have this neck of the femur, right?
That's gonna create that angle.
So, as we start to come up into here, right
with that flexion or what this neck of the femur
is gonna do is, it's going to create this little bit
of rotation and as this rotates, because of that neck
it also will abduct, right?
So, we're gonna see that in order to get fully hip flexed
as this comes up for all,
for us to make space for all this tissue
there's gonna have to be this small amount
of external rotation and abduction
that's going to allow for that.
So, if we were to take Chelsea through that range of motion,
if she keeps her leg straight up and she just lifts.
Like, that's the end right there of hip flexion
before we would start to see the pelvis start to roll.
So if I jam her here, that's now pelvic tilt
not ex-not more hip flexion.
So, even though these muscles are pulling this way
if we tried to come in too much towards that psoas
right, we're actually gonna be jamming the joint
before we reach full shortening,
similar to over externally rotating,
or abducting for the glutes.
So, this path actually has to go along
with the angle of the pelvis and the neck of the femur.
So, it's going to come out, it's going
to abduct and have an external rotation force
and that's going to be full hip flexion.
If you imagine these muscles as they come in,
they attach right, are now kind of at an angle like this
because they attach slightly on the medial side
of that femur.
So, that's actually gonna be a shorter position
which, consequently is also our lengthened position
for a glute in this position right here.
So, if we think about fully finishing that arc of the glute
like if we're looking at a sprint, this position,
the fully shortened hip flexion position is gonna be
our most lengthened glute
and then are fully shortened glute that we demonstrated
which was this kind of arced around and back in
is now going to be the fully lengthened hip flexors.
Right? So to get to full hip flexion
we are also getting to a full stretch on that.
So, as into a, get to a full shortened hip flexion
where you're getting a full stretch on the glute.
So, you can imagine that those two muscles
the glute complex and kind of like this
psoas complex is going to have a synergistic
relationship similar to the rectus femoris
and the hamstrings, meaning that they're kind
of managing length, tension relationship to affect all
of the muscles that are going to end
up stabilizing the pelvis
as we're doing hip flexion extensions,
so, there is this communication
between these true like agonist, antagonistic muscles
that really affects the integration
of all of the muscles around that complex.