 Shall we talk about the muscles that move the forearm? Forearm movement, granted, we can pronate and supinate, and there are definitely muscles that are involved in that, but for the most part, we're talking about forearm flexors and forearm extensors. We actually only have one forearm extensor, and who is that? You know that's triceps. And if triceps is extending the forearm, and let's make sure we're good, that we're talking just extension of the forearm, where does one of our attachments have to be on the forearm? And in fact, go ahead and take a wild guess. Those of you who know me quite well, it attaches to my favorite bone bump. What is it? It attaches to the alecranon. There it is. Don't make me mad, or that thing will be like, wap, wap, yeah. So the alecranon is the elbow bone, elbow bump that is found on the posterior surface of the ulna. So triceps brachii, all of them attached to the alecranon. Now, two of the heads, triceps, means there are three heads. You have a long head, a short head, and a lateral head. Oh, jeez, they're not even long lateral medial, any of that. And the lateral head and the medial head attach to the humerus. So they like attach to the shaft of the humerus. But do you remember how I told you there was that one that snaked between Terri's major and Terri's minor? That's the long head, and it attaches to the scapula. It attaches to the scapula near the glenoid cavity. And so because of the long head, we have a little bit of arm movement. We have a little bit of arm extension as well. But that's only the lateral head that's responsible for the arm extension. The rest of the tricep is really just for arm extension. Let's go look at that one really fast. Look, who is that? No, that's not where I'm looking. Okay, look, oh, here's latissimus, here's triceps. The, whatever head this is, the lateral head and the medial head is deep. And they're like truly smushed onto the muscle itself. There's so many attachments onto the muscle that you can't really, I like muscles where you can grab the attachment and wiggle it. And triceps is very challenging. You shred it if you try to pull it up off the bone. Sad story, but the long head of the triceps is easy to find because it passes between Terri's minor and Terri's major. Okay, life is fantastic. Let's get rid of our triceps and go figure out what our next one is. Let's do biceps next. We have two heads that you have to know of the biceps. You have the long head, which we already know that one, right? Because remember the long head of the biceps tendon passed between the two tubercles, the greater and lesser tubercle, in the inter-tubercular groove, good lord. It's also known as the bicepital groove. Dude, who came up with inter-tubercular groove? Bicepital groove is way cooler. So the long head travels through that groove and comes up and attaches to the scapula by the glenoid fossa, fossa, fossa on the superior end. The short head, this is nice. The short head attaches to the coracoid process. Why am I not writing these down? Why didn't you remind me to write them down? Okay, short head attaches to coracoid process. Long head attaches to above the glenoid fossa, fossa, fossa. And I say above, it's actually a bump called the superglenoid process, but we didn't learn that one in our boom bumps, so you can just know that it attaches near the glenoid fossa. Who else attaches to the coracoid process? Peckminer attaches to the coracoid process, so they share because we're friends. Biceps brachii, there's a little bit of messiness in the distal attachment, but the piece that I want you to know is that biceps, we'll just say both of them, attach to the, I can do this, it's on the radius, I think it's the radial tuberosity. I can see it in my head, I just want to make sure I have the right name for it. Radial tuberosity, and it's so cool because, well, we'll talk about the biomechanics of biceps brachii and we'll have a push-up, push-up challenge in class. That'll be super fun and I'm really competitive, so I better start training. All right, major action, both, okay, now think about this. We are traveling from the radius across the humerus and up to the scapula, so tell me about the actions that we're going to have. Across the elbow joint, so one of our actions is going to be flexion of the forearm, and that makes sense, right, and you can feel it, flex your bicep when you contract your bicep, when you flex your forearm at the elbow joint, you're cool. But that's just one piece of it because your bicep is also activated when you flex your humerus, when you flex your arm at the shoulder joint. And I'm trying to say that these happen at both, like both of my bicep flavors are responsible for arm flexion and forearm flexion because both of them attach to the radius, which is distal to the elbow joint, cross that joint, cross the shoulder joint as well and attach to the scapula. Biceps, rockin' two joints, doggies, that's exciting. Brachialis, brachialis is a flexor. It does not cross two joints. It only crosses the elbow joint, so it flexes the forearm, and let's see if I can remember where brachialis attaches. It smashes onto the humerus, so it attaches to the shaft of the humerus on the anterior surface and deep to biceps. And then my other attachment is gonna have to be, I know it has, oh, I got it. See, this is why you had to learn these things. What bone am I being right now? Oh, this is my favorite part of the bone, whack, whack. Okay, this is your ulna. And do you remember that little annoying process? That's the coronoid process. Remember that thing? I gotta make sure that I'm correct. Let me make sure. Brachialis, coronoid process? Dude, I studied all night last night and I'm rockin' this thing. Now think about this, coronoid process. And who was the coronoid process on? I was trying to do that little whole thing. It's on the ulna. So, coronoid process, ulna, two smashed on the humerus, strong, like crazy, strong forearm flexor. When brachialis and biceps work together, you aren't messin' around unless, of course, you pronate. Uh-uh. But I'll fight you because we'll have a competition, a pull-up chin-up competition. And I know the trick. I know how to make sure biceps and brachialis are engaged. Brachioradialis. Brachioradialis is clutch for making sure that you can identify the next set of muscles, which are all hand and finger movers. Okay, whatever. So, brachioradialis, brachioradialis, which side is it gonna be on, medial or lateral? Let's just be loud and in charge. It's lateral because it's on the radial side. And guess what one of its attachments is? The distal attachment is to the styloid process of the radius. That's why we had to know that one, you guys. And then its other attachment is somewhere on the humerus. Shall we check where? Brachioradialis, lateral, distal, humerus. I love that. Look, lateral, distal, humerus. And what does it do? Flexes the forearm. All right, let's go look at them really fast before we do anything else. Because I know you want to do other stuff. Where are we? Triceps were good. Let's look at biceps brachii. We talked about biceps brachii. It's two pieces. It's attached to the radial tuberosity. Think about what happens if you pronate your hand, what happens to your radius and what might happen to that little biceps tendon. The long head of biceps, long head is lateral. It passes between the tubercles through the inner tubercular groove. It attaches superior to the glenoid fossa. Fossa, fossa, fossa. The short head is medial. The short head, I mean, I'm looking at this going, dude, the short head looks longer than the long head. It's always helpful. So just go with short head is medial. Short head travels up and attaches to the coracoid process on the scapula. Fantastic. And we're going to have flexion of the arm and the forearm with this because it's spanning two joints. That would be an awesome test question to analyze. I could give you a scenario where I'm not telling you the muscle name, but I could tell you it spans two joints and it, I don't know how I would say that, but your answer to this question that I don't know how to say it is, it spans two joints. So it's going to cause movement at two joints. Okay? So memorize that. Oh, geez. Let's look at brachialis. Remember I said brachialis was deep to biceps. So if we peeled back biceps, we would see brachialis underneath there. Biceps would go up over the top. In fact, let's put our biceps back on. See how biceps is on there? Let's get rid of biceps and now we can see brachialis deep. It smears on to the shaft of the humerus and it comes down and it attaches to the coronoid process of the ulna and is a really powerful forearm flexor. And then brachioradialis. Now look at this thing. Brachioradialis is weird because it's a long, long, long muscle, but it isn't a hand mover. It doesn't cross the wrist joint. It just goes from the lateral distal end of the humerus all the way down to the styloid process on the radius. So that puppy's going all the way down. Now you have a wad of muscles right here, also known as the mobile wad of Henry. Dude, how awesome is that? Everybody palpate your mobile wad of Henry. Seriously, brachioradialis is part of the mobile wad of Henry. All right, the good news is we have one left and our last section is all about muscles that move the hand at the wrist joint, although we do have some phalange flexors and extensors. These are the flexors. K, I'll see you in a second.