After learning about the superficial muscles, this video will discuss more about the deep muscles of the anterior compartment of the arm.

Enjoy!

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 this video is brought to you by our partners over at 3D4Medical.com, the creator of this app. This is an iPad which I’m using right now. It’s called The Muscle System Pro III. It’s available on iPad, iPhone and also for the Mac operating system.

You can check it out in the App store. Once again, the name is Muscle System Pro.

In this video, I’m going to be talking about the deep muscles of the anterior compartment of the forearm. More specifically, first I’m going to talk about the innervation for those muscles in the deep layer of the anterior compartment and then, I’m going to talk about the three muscles in that deep layer of the anterior compartment of the forearm.

Let’s get right into it.

In the last video, you saw that we went over, or if you didn’t see, you can go and check it out. We spoke about the superficial muscles in the anterior compartment of the forearm so, we’re not going to pay attention to those. I’m going to start peeling back layers, getting rid of some of those superficial muscles.

I want to really quick, before I actually get to that deep layer, I want to point out really quick that this muscle is the flexor digitorum superficialis that we looked at in that previous video. I’m actually going to remove than one but, I want to just show you how broad that muscle is. This is the one that we said that is going to be underneath the other muscles of the superficial layer. So, let’s get rid of that.

Now, we can see the muscles in the deep layer of that anterior compartment.

Now, in terms of the innervation to those muscles, that’s going to be done by the anterior interosseous nerve. That’s a branch of the median nerve. If you remember, we spoke about the cubital fossa and we had the median nerve coming down into that cubital fossa. It’s going to continue on but, as it continues on, it’s actually going to give out some branches. One of those branches is going to be the anterior interosseous nerve.

The reason we call it the anterior interosseous nerve is because right here, between the two bones, we have the interosseous membrane and since it’s anterior to that membrane, it’s going to be the anterior interosseous nerve which also tells you that there’s also going to be a posterior interosseous nerve.

So, that’s the innervation. The anterior interosseous nerve which is a branch of the median nerve. If you remember, we said, most of the muscles of the anterior compartment are going to be innervated by this median nerve. Here it is the median nerve but, via specifically the anterior interosseous nerve.

Now, there is one exception. That is this muscle here which we’re going to look at in a little bit. That’s our flexor digitorum profundus. Profundus refers to deep and this is the deep digitorum muscle, I guess you should call it.

That muscle, it’s going to be innervated, yes, by the anterior interosseous from the median nerve but, only half of it. So, the lateral half or the radial half of that muscle, that is going to be innervated by the anterior interosseous nerve which makes sense since that nerve travels right here.

But, the medial half of that nerve, that is going to be innervated by the ulnar nerve. So, the ulnar half is going to be innervated by the ulnar nerve. All of the rest, the other two muscles, basically, that’s going to be innervated by the anterior interosseous. This one, only half of it is going to be by anterior interosseous from the median nerve. That’s the innervation.

Now, let’s talk about what the muscles are. The first one, we already looked at and that is our flexor digitorum profundus. Digitorum, usually when you see that digitorum, whenever you see that  digitorum when we’re talking about these muscles, whether it’s superficialis or profundus, you’re going to see this split tendon. We see these multiple tendons going to the individual digits. That is our flexor digitorum profundus.

Then, we have our flexor pollicis longus. That’s this muscle that you see here. ” refers to thumb and you see that we have the tendon that goes over and then, inserts on the thumb specifically the distal phalanx of the thumb. We’re not going into all the origins and insertions. You can go back to the website and I’ll talk about that at the end to get that information.

So, those are the first two of the three muscles. We only have one more to go, right? And, in order to see that one, we have to actually dig a little deeper. We remove those layers and then, we see we have our pronator quadratus which is this flat muscle that you see going between the ulna and the radius. So, it’s running down laterally and a little inferiorly. It’s going from the ulna to the radius and that is your pronator quadratus.

That’s pretty much all the content. Let’s review that really quick.

The innervation for the muscles of the deep layer is going to be mostly the anterior interoseouss nerve which is a branch of the median nerve except for flexor digitorum profundus, the ulnar half of that muscle is going to be innervated by the ulnar nerve.

Then, the muscles that you find in this deep layer would be number one,we have our flexor digitorum profundus. Number two, we have our flexor pollicis longus and number three, we have our pronator quadratus.

That’s all of the muscles. That’s the innervations. That’s pretty much it for this video.

This is Leslie Samuel. If you want more details about this video specifically, this is going to be video number 106. Come to interactivebiology.com/106 and you’re going to get information on the insertions, the origins, and the actions, all of the details for these muscles in this particular group.

But, that’s all I have to talk about in this episode. This is Leslie Samuel from Interactive Biology TV where we’re making Biology fun. That’s it for this video and I’ll see you in the next one.