00:01
Now let's have a look at these
muscles in a bit more detail.
00:03
So let's have a look at the
posterior thigh muscles.
00:07
Here we can see a number of
muscles that form in this location.
00:10
We have semimembranosus,
and we have a
similarly named muscle
known as semitendinosis.
00:16
The difference between these two
apart from their positioning
is that the semitendinosis
has a very thick tendon
that actually starts
quite more proximately
than semimembranosus,
which has a slightly
flatter muscle
helpings, give them
their two names.
00:30
So running on the medial aspect,
we have semimembranosus,
semi tendinosis,
and then running more
on the lateral aspect,
we have biceps femoris.
00:39
As its name implies,
like biceps brachii,
it has two heads.
00:43
Let's have a look
at semibranosus,
the origin and insertion
of semimembranosus.
00:49
The origin is it comes down
from the ischial tuberosity
and it goes and attaches
to the posterior surface
of the medial tibial condyle.
00:58
So we see it runs distally
down towards the leg.
01:02
Semi tendinosis, this also comes
from the ischial tuberosity.
01:05
It lies more superficial
than semimembranosus.
01:08
But it also goes and
attaches to the tibia.
01:11
This time is attaching
to the medial surface
of the proximal tibia.
01:16
So it's attaching just medial
to the tibial tuberosity.
01:21
Biceps femoris is the more
laterally positioned muscle
in the posterior thigh.
01:25
And here we can
see it's long head,
remember biceps means
it has two head,
its long head is coming
from the ischial tuberosity.
01:33
It also has a shorter head
and this is coming
from the linear aspera.
01:37
Remember that line on the
posterior aspect of the femur.
01:41
So the two heads,
long head, short head,
coming from the
ischial of tuberosity
and the linea
aspera respectively.
01:48
And then passes
down and attaches
to the head of the fibular.
01:53
These muscles are supplied
by the sciatic nerve,
but primarily they also
have an important function
in movement of the knee.
02:02
So here we can see
the position of the
hamstring muscles
is sitting very much
posterior to the femur.
02:09
Now what this means is,
as it runs posterior
to the femur,
it runs posterior
to the knee joint.
02:15
And as it actually runs
posterior to the knee joint,
it is going to flex the knee
as it moves the knee backwards.
02:22
So here we see flexion
of the knee joint
as the hamstring muscles
cross the knee joint
and attach to the neck.
02:28
So that's going
to flex the knee.
02:30
As they also cross the hip joint
as they're attaching to
the ischial tuberosity,
contraction of these muscles
will also lead to extension
of the hip joint.
02:40
So the hamstrings are
important in flexing the knee
and also extending
the hip joint.
02:46
If we have a look at
the neurovasculature
of the posterior thigh,
here we can remove biceps
to see clearly sciatic nerve
and we can see a number of
various perforating arteries
that are coming from
the deep femoral artery
and these are running down
and how many to supply the deep
substance of these muscles.