 In the early stages of your life as a fetus, certain parts of your external genitalia were inside your abdomen. As they pushed their way out, they created for themselves this space that we now know as the Inguinal Canal. It's a space that begins a couple of centimetres above the halfway point of the Inguinal ligament which runs like this. To make it easier to visualise, we've got it here as a rounded cubic prism. The two ends of the canal are called the Inguinal rings, superficial and deep. The contents of the canal are in males, the spermatic cord, and in females, the round ligament. In both, there's the ilio-inguinal nerve as well. So let's think about what holds these things in the canal, the walls that mark the edges of the prism. The bottom wall is the easiest to remember, it's the Inguinal ligament we mentioned before. The outer or anterior wall is also easy to remember, it's mostly made up of the aponeurosis of the external oblique. The external oblique is the most anterior muscle of the abdominal wall, so you have the anterior wall of the Inguinal canal made up by the most anterior muscle. Interestingly, the Inguinal ligament is actually just an extension or a continuation of this aponeurosis. And further out laterally, the anterior wall is reinforced by the next muscle of the abdominal wall, internal oblique, or IO. For our purposes, this starts at the iliac crest, this bony prominence here. It moves that beside the external oblique, and is joined here by the next muscle of the abdominal wall, which begins further lateral on the iliac crest. That's transversus abdominis, or TA. So IO and TA join together to arch over the top. So what we imagine is the superior wall of the Inguinal canal is simply the part of these muscles which is flying free, arcing over the contents of the canal. They end up joining together to make the aptly named conjoined tendon, which inserts onto the pubic cubicle down here. If we take a look around the back now, you can see that the conjoined tendon actually extends down over part of the posterior wall of the Inguinal canal. So IO and TA have made this journey from the iliac crest, making up part of the anterior wall, all of the superior wall, and then a little bit of the posterior wall of the Inguinal canal. And if we think about it, we've used up all of the abdominal wall muscles now to make up the inferior, anterior, and superior walls. So what else is there between the skin and the abdominal contents? What's going to hold the abdominal contents away from the contents of the Inguinal canal? So we've used up IO, IO, and TA in that order from skin to abdominal cavity, and the last layer isn't a muscle. It's a layer of fascia called the transversalis fascia. It's the last thing we meet in terms of layers from the skin to the abdominal contents. And interestingly, the deep Inguinal ring is actually a hole in the transversalis fascia. So now we've worked all that out, let's take a trip down the canal. We'll hop through the deep ring first, which is the hole in the transversalis fascia. We see right in front of us the muscle reinforcing the anterior wall, the Inguinal canal, that's internal oblique. And then to our right, we see this other muscle that joins up with internal oblique to arc over our heads and make up the superior wall. And that's transversus abdominis. Medially to them on the anterior wall is the aponeurosis of the external oblique. Keep cruising on down the canal now, and we see the transversalis fascia on our left. And then further down from that, we see the end of the posterior wall made up by the conjoined tendon, which of course is the joint tenderness insertion of Io and Ta. The floor is the Inguinal ligament, which is just an extension of the external oblique aponeurosis. And then lastly, to our right, we see a hole in the external oblique aponeurosis, the superficial Inguinal ring. So through this hole we go, and if it's a male we're in, we hop out that ring and land in the scrotum. And if it's a female, we'll end up in the labia majora. All right, so there you go. I hope you enjoyed that little journey through the Inguinal canal. Thanks for watching. Hit subscribe, and we'll see you next time.