00:01
If we then move on to the thigh, we then want
to look at the thigh in cross-section.
00:06
We?re familiar with this view from the upper limb.
We have the outer skin, and then we have the
medial aspect here. Remember, we?re looking
at it from below. So medially, we find the
great saphenous vein within the subcutaneous
tissue. Laterally, we find the iliotibial
tract. And here we have fasciae latae, and
this passes deep into the thigh. We can see
the lateral femoral intermuscular septum here.
And then we can see we have this posterior
intermuscular septum passing through here, and
we can see we?ve got this middle intermuscular
septum. And these separate the thigh into
three compartments; the adductor or the medial
compartment which we can see here, we can
then see the anterior compartment here, and
we can see a posterior compartment which we
can see here. And these are all separated by the
intermuscular septum. So it?s been separated
into the various parts. We can also see that
we have the sciatic nerve here and we have
various branches coming here from the femoral
nerve, and these are going to supply the various
muscles within these compartments. The anterior
compartment supplied by the femoral nerve
is going to be the extensor compartment, and
this is going to extend the knee. The posterior
compartment is the flexor compartment supplied
by the tibial nerve, and this is going to
flex the knee. And then we have the medial
compartment known as the adductor compartment
supplied by the obturator nerve and this is
going to adduct the thigh. The movements of
these muscles in the thigh, they act on both
the hip and the knee joint, and there are
two types of movement. We have flexion and
extension that?s allowed to occur at the
hip, and also at the knee. And we also
have adduction. Adduction is created via the adductor
compartment, the medial compartment, whereas,
abduction is carried out by muscles within
the gluteal region. So if we have a look at
the posterior thigh, then we can see there
are just a few muscles to see. We?ve got
semitendinosus and we?ve got semimembranosus.
These muscles are coming from the ischial
tuberosity and they pass straight down the
medial aspect of the leg, we can see here.
02:32
We?ve got some biceps muscles that are running
down the lateral aspects. And as we can see
on this diagram, some of these muscles from
a very intimate relationship as they have
a common tendinous insertion onto the anteromedial
aspect of the knee joint. So if we have a
look, we?ve got biceps femoris, the long
head and the short head, similar to biceps
in the upper limb, it has two heads. The long
head comes from the ischial tuberosity and
the short head comes from the linear aspera
and the lateral supracondylar line.
03:09
So if we look at biceps, we can see the long head
here is coming from the ischial tuberosity.
03:13
It?s passing all the way down. It?s then
joined by the short head that?s coming from
the linear aspera, and these then combine to
attach to the fibula. We can see them attaching
to the lateral surface on the head of the
fibula. Biceps is quite important.
03:30
It has two nerves that supply it. The long head is
supplied by the tibial division of the sciatic
nerve. So the long head of biceps is supplied
by the tibial division of the sciatic nerve.
03:44
The short head, however, is supplied by the
common fibular division of the sciatic nerve.
03:50
So the biceps has two different nerve supplies,
long head tibial division, short head
common fibular. The biceps femoris is associated
with flexing the knee joint, and also, laterally
rotating it when flexed. It can also extend the
hip joint. If we now look at semitendinosus
and semimembranosus, these originate from
the ischial tuberosity. We can see both of
these muscles coming from the ischial tuberosity
of the ischium and passing down the medial
aspect of the thigh. Semimembranosus is deeper
than semitendinosus with semitendinosus having
this tough and cylindrical-shaped tendon. We
can see both of these coming from the ischial
tuberosity. Semitendinosus passes to the medial surface
of the proximal tibia, whereas, semimembranosus
passes the posterior surface on the medial
condyle of the tibia. So, both of these are
passing to the tibia. Semitendinosus is passing
to the medial surface of the proximal tibia
and membranosus is passing to the posterior
surface of the medial condyle of the tibia.
05:06
These are supplied just like the long head
of biceps by the tibial division of the sciatic
nerve. These muscles which collectively can
be known as the hamstrings including biceps
femoris, but semitendinosus and semimembranosus
extend the hip joints and they can also flex
the knee joints. They?re also associated
with medial rotation when it is flexed.