 Hey everybody, Dr. O here and this is when I cover some of the key muscles in the trunk area. So here we have your abdominal muscles, the rectus abdominis, the internal and external obliques and the transversus abdominis. The reason I talk about all these at one time besides the fact that they share functions is that it kind of functions like a muscular back brace that compresses the abdomen and stabilizes your low back. The rectus muscles, the rectus abdominis means straight, these muscles run straight up and down. That'd be your six pack and they're involved in flexion of the trunk and spine there. Then you have the internal and external obliques that run at these 45 degree angles and they run in different directions. So they play a big role in rotation and also lateral flexion of the trunk but they stabilize the abdomen as well. Then you have the transversus abdominis which is deep. You have to remove all these other muscles but it runs side to side so its job is to compress the abdomen. This is probably the most important one from a low back standpoint. If you can strengthen the transversus abdominis and help people compress their abdomen that should stabilize their low backs when they're moving, lifting things, getting out of bed, these types of things. So having a strong core is really, really important to protecting your back. Not because you're making your back muscles stronger but you're stabilizing your backs. You don't get serious issues if you catch yourself in an awkward position. So those are going to be your abdominal muscles, rectus abdominis, internal oblique, external oblique and transverse abdominis. Then if you go a little deeper, we have two more really important ones. Now you might see this term ilio-soas so the ilio-soas is actually the iliacus muscle plus the soas muscle which I'll point to here. But the soas is the one that I want to focus on. There is a soas major and minor but the soas major is super important muscle. It's the connection between the vertebra of your low back and your hip. So its job is primarily flexion of the hip but it's also a lateral or external rotator. This one's so important because it gets super tight in people that sit all the time. I notice back clinically I do a lot of work to get people to stretch their soas and to work out the soas muscle. It's also a real common cause of anterior hip pain and that snapping. Like if you hear like a snapping or popping in the front of the hip, I noticed that a lot of times the soas major was very tight. So the soas is really kind of our loin muscle just kind of interesting there. But so if you see ilio-soas, it's this iliacus plus the soas. But out of all of them, the soas major is the one I want you to know. Then we have the quadratus lumborum or what's called the QL. Another one, this one connects the pelvis to your lumbar spine and even your bottom rib. So very common in people with achy tight low backs, this quadratus lumborum muscle gets super tight. It's involved in lateral flexion of the trunks. These might be the kind of muscles that need worked out with a really good massage or myofascial release session if you have a lot of chronic low back pain. But for now, just know where they are. So that's the soas major and the iliacus which form that ilio-soas. The quadratus lumborum is there as well. Then we already covered the abdominal muscles. So some of the key muscles of the trunk. All right, I hope this helps. Have a wonderful day. Be blessed.