Internal Oblique – Anterolateral Abdominal Wall

00:00 Let's move on and deep to this muscle, deep to external oblique, we find internal oblique.

00:08 So, here on the diagram, we can see external oblique here is being cut away and we are left with this muscle that?s radiating underneath. So, here we have some details. You can notice that the fibers of internal oblique run in the opposite direction to that of external oblique and this is really important. So, external oblique is running down in this direction, like you are putting your hands in your pockets, external oblique. Internal oblique radiates downwards and backwards, so like you are forming the roof of a house and these fibers run in this direction, away from the midline. And this is internal oblique. We have got some details of its origin and its insertion here. It originates from the iliac crest, from the pelvic bone and also, an important piece of fascia most posteriorly go to thoracolumbar fascia. It also attaches to the inguinal ligament and we will see that in more detail when we look at the inguinal canal. As its running up in this direction, we can see it inserts into ribs 10 and 12 and there also lies some aponeurosis, which we will talk about, the internal oblique muscles attached to the linea alba. Nerves supply, again, is similar to the external oblique and rectus abdominis and it?s the thoracoabdominal nerves coming from the spinal cord T6 through to T12. Internal oblique does the same function as external oblique. It helps to flex and rotate the trunk enabling us to... to move and importantly, like I mentioned before, it helps to compress the internal viscera, increase the pressure and support the abdominal cavity. So, we have got internal oblique that lies deep to external oblique.