 There we go, Dr. O here. In this video we're going to cover all the key muscles involved in pronation and supination. So let's talk about those actions. So supination, simple sweater, remember it is you make a bowl of soup. So if you put your forearms in the position where you can make a bowl of soup, they are supinated. Pronation, you're turning the palms of your hands backwards if you're in the anatomical position. Supination, your palms, your hands would be anterior. So that's going to be pronation and supination that was covered in their places. Here we see the first one is the biceps brachii. So it does primarily flex the elbows but it's also a very powerful supinator, the most powerful one we have. So the biceps brachii flexes the elbow but also supernates the forearm. That's the biceps brachii. Here in this image you also see the pronator teres. Teres basically means like cigar shaped muscle. So the pronator teres, like the name implies, it's a pronator muscle. This one's really important. We'll cover this one more in the nervous system. But the median nerve, in about 10% of people give or take, the median nerve runs through this muscle and everyone else it runs underneath it. So if you get a really tight pronator teres muscle, which can happen from using tools a lot, typing a lot, these kind of things, you get a really tight forearm, the pronator teres can actually put pressure on your median nerve and give you the symptoms of carpal tunnel syndrome. So I've had multiple patients that were scheduled for carpal tunnel surgery and I was able to loosen up the muscles in this area and get them stretching it and rehabbing it and they didn't need the surgery. So not medical advice, but if you have carpal tunnel syndrome symptoms, I definitely recommend getting your elbow looked at to make sure that the forearm muscles aren't super tight and they aren't causing part of the problem. So biceps brachii is a supinator, pronator teres is a pronator. We also have the pronator quadratus down here at the bottom, near the wrist. It's named that because it's a pronator and also it's shaped like a box. That's your pronator quadratus. In this last image here we have a muscle called the supinator, like the name implies. It's a supinator, so it supinates the forearm. All right, so those are the four key muscles, biceps brachii and supinator are both supinator muscles and the pronator teres and pronator quadratus are both pronator muscles. Okay, I hope this helps. Have a wonderful day. Be blessed.