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Today we'll explain the muscles of the abdominal walls. This is the anterior abdominal wall,
and this is the iliac crest. Attached, to the iliac crest and forming the anterior abdominal
wall are three abdominal muscles that will form the *** sheath. They are arranged
from superficial to deep, number 1: the external oblique muscle, this is the external oblique
muscle, where the fibres are directed obliquely. Then, will have the internal oblique muscle, also the
muscles are directed obliquely. Then will have the inner most muscle which is the transversus
abdominis, where the fibres are arranged transversely. Therefore, to the iliac crest, we have the
external oblique muscle, we have the internal oblique muscle, and we have very close to
the internal oblique the transversus abdominis, where the fibres are are arranged transversely.
These, muscles forms the *** sheath medially, (the aponeurosis) forms the *** sheath.
So, if I go medially, this will be the anterior wall of the *** sheath. Then, we'll have
the *** abdominis, where the fibres are arranged in a vertical direction and it has
tendonitis intersections, dividing it into sections. So, medially the aponeurosis of
the three muscles will form the anterior wall of the *** sheath, then I'll find the ***
abdominis with the tendonitis intersections, then when I reflect the *** abdominis,
I'll find the posterior wall of the *** sheath. So, these are the: posterior wall
of *** sheath, the *** abdominis and the anterior wall of the *** sheath. When,
I remove the anterior abdominal wall and I look backward to the vertebrae "these are
the vertebrae". Anterior, to the vertebrae to the left side, there will be the abdominal
aorta and on the right side, there will be the inferior vena cava. So, the main vessels,
which are lying on the vertebrae, is the aorta and the inferior vena cava. Coming from all
lumbar vertebrae, are the two psoas major muscles, which arise from the sides of the
bodies of the vertebrae and from their transverse processes and from the internal vertebral
disks between them. Lateral, to the psoas major, " this is the iliac crest, as we agreed"
and here is the iliac fossa. From, the iliac fossa arises the iliacus. So, we have two
vessels lying on the vertebrae and the disks, which are the aorta and the inferior vena
cava. From the sides of the vertebrae and their disks arises the psoas major, and as
we go down, there will be the iliac crest and the iliac fossa, giving origins to the
iliacus. Then, the iliacus and the psoas major will join together to form one muscle which
is the iliopsoas muscle, that it will descend in front of the hip joint to become inserted
into the lesser trochanter of the femur, the iliopsoas is the main muscle that flexes the
hip joint. So, "the psoas and the iliacus are joined to form the iliopsoas". Again,
on the other side, this is the psoas and this is the iliacus, they join together to form
one muscle, their fibres become close to each others and join together to form the iliopsoas,
that will descend down to the lesser trochanter of the femur. Between, the psoas major and
the iliacus and crossing the iliacus, we'll have two important nerves, lateral to the
psoas major, these nerves which is the nerve supply of the iliacus also, and the muscle
of the front of the thigh, is the femoral nerve , "it is lateral to the psoas and crossing
the iliacus". Also, crossing the iliacus, there is a thin nerve that it is directed
towards the iliac crest, towards the anterior superior iliac spine, this nerve is the lateral
cutaneous nerve of the thigh. So, lateral to the psoas major and crossing the iliacus,
we'll have the femoral nerve and the lateral cutaneous nerve of the thigh. Anterior, to
the psoas major we'll find that the psoas major is pierced and crossed vertically by
a very thin nerve, which is the genitofemoral nerve. Of course, the genitofemoral nerve
from its name, will divide into a genital branch going to the cremasteric muscle and
a femoral branch that will go to the muscles of the medial side of the thigh. So, this
very thin nerve that pierces the psoas major and passes anterior to it, will be the genitofemoral
nerve. Just, medial to the psoas major we'll have two important nerves, the obturator nerve,
which arises from the same root of the femoral, from the lumbar ventral rami "2,3,4" (from
their ventral divisions), the femoral arises from their dorsal divisions, so they have
the same roots. This is the femoral and this is the obturator, and deep to the obturator,
we'll find a thick nerve, which is the lumbosacral trunk, that arises from the lumbar nerves
"4 &5"