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097 Innervations Of The Arm Muscles

In this video, Leslie talks about the muscles of the arm and the nerves that innervate them. Did you know there are only two nerves? What are these? Find out by watching the video.

Have fun!

Transcript of Today’s Episode

Hello and welcome to another episode of Interactive Biology TV where we’re making Biology fun. My name is Leslie Samuel and in this episode, I’m going to be talking about the innervations of the arm muscles. We’re talking about the muscles in the arm. Let’s get right into it.

When it comes to the innervations of the muscles in the arm, there are only two nerves that we need to be concerned with. Remember, I’m not dealing with the forearm, just the arm. Those two nerves are the musculocutaneous nerve, and you can see that here. It comes from the lateral branch of the lateral cord, the musculocutaneous nerve; and the radial nerve. You can see the radial nerve right here. That is the medial branch of the posterior cord. Those are the two nerves that we are concerned with with the arm muscles. They’re going to innervate all the muscles in the arm. So, let’s look at all the muscles in the arm.

I don’t know if you ever noticed before but, when you go to the gym, there’s always a guy there or maybe more than one guy that really wants to show how muscular that person is, that guy is. So, he’d stand in the mirror. He’d flex his arms. He’d be saying that he’s flexing his biceps and these are the muscles that guys really flex to say, “You know what? I am strong. I have big muscles.” These are going to be the flexor muscles of the arm and those are innervated by the musculocutaneous nerve.

That’s why I want you to remember it. “Musculo,” so very muscular. The guys in the gym, thinking they’re very muscular in the mirror, flexing their arms. Those are innervated by the musculocutaneous nerve.

So, those muscles would be… What are the flexor muscles of the arm? We have, of course, the biceps brachii, these are the ones that we talk about a lot. And then, we have the brachialis, that’s going to be right beneeath the biceps brachii. Then, we have coracobrachialis.

  • Coracobrachialis
  • Biceps brachii
  • Brachialis muscles

Those are all innervated by the musculocutaneous nerve which is the lateral branch coming from the lateral cord. That’s on one end.

Then, of course, when I used to workout, I used to workout with a partner that keep telling me, “If you want your arms to look big, yes, biceps are great, but really, if you want them to look really great, you want to work on your triceps.” Alright, so that’s these extensor muscles, the triceps.

This is how I want you to remember this. If you want your arms to look really radical or radial, I don’t know if that works… If you want it to look really awesome, really radial, you got to work on those triceps.

So, the radial nerve, that’s going to innervate the triceps muscles. You can see those here, here we have the triceps– the lateral head and the long head. Of course, you’re not seeing the medial head but, the triceps are innervated by this radial nerve which is the medial branch of the posterior cord.

So, in review. This is a very short one. There’s not much to learn here. When it comes to the flexor muscles, the coracobrachialis, biceps brachii, and the brachialis muscles, those are innervated by the musculocutaneous nerve. Then, the triceps brachii are innervated by the radial nerve.

That’s pretty much it for this video. If you enjoyed it, make sure to click on the ‘Like’ button right beneath if you’re on YouTube and you can subscribe by clicking on the ‘Subscribe’ button above.

That’s pretty much it for this video. Of course, make sure to visit the website at for more Biology videos and other resources to help make Biology fun. This is Leslie Samuel and I’ll see you in the next one.

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About The Author

Leslie Samuel

Leslie Samuel is the creator of Interactive Biology. His mission is to use this site to Make Biology fun for people all over the world.