In this video, Leslie discusses more about the three muscles of the anterior compartment of the arm namely the Biceps Brachii, Coracobrachialis and Brachialis. He also mentions their innervations and functions, as well.
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 sponsors over at 3D4Medical.com, the creator of this app which is called the Muscle System Pro and a number of other Anatomy apps.
This one is available on the iPad, iPhone and also for your Mac OS. You can find them by going to the App store and searching for the Muscle System Pro.
In this video, we’re going to be talking about the anterior compartment of the arm. More specifically, first I’m going to talk about the muscles of the anterior compartment. Then, I’m going to talk about the innervation of the anterior compartment and lastly, the function of the anterior compartment.
So, let’s get right into it.
The Muscles of the Anterior Compartment of the Arm
I’m going to zoom in to the arm and we’re going to look first at the muscles. There are three muscles that are found in the anterior compartment of the arm. And, of course, when we’re talking about the arm, we’re talking about the region between the shoulders and the elbow. And, anytime we refer to that region, we’re referring to the brachium.
Brachium is the Latin word for arm so that’s what we’re referring to. These muscles are going to have some version of that word brachium. In order to see all of the muscles, first I’m going to remove the deltoideus muscle and then, we can look at the first muscle which is the biceps brachii. That’s the one that you always think about when you think about the anterior compartment, the biceps brachii.
The reason for the name biceps is because we have these two heads — the short head of the biceps and the long head of the biceps brachii. You can see one is coming from the coracoid process and the other one has a tendon that comes from the supraglenoid tubercle.
That’s the first muscle, the biceps brachii. In order to see the others, I am going to get rid of my biceps brachii and now, we can see the other two muscles.
The next one is the coracobrachialis which is this guy right here coming from that coracoid process and then, inserting on the humerus. That is the coracobrachialis and lastly, we have the brachialis muscle.
You see, they all have brachium somehow in there. We have brachialis, we have coracobrachialis, and we have biceps brachii. Those are the three muscles.
The Innervation for the Muscles of the Anterior Compartment of the Arm
Now, what is the innervation for these muscles of the anterior compartment? That is the musculocutaneous nerve. The musculocutaneous nerve is the innervation for all three of the muscles in the anterior compartment.
Functions of the Anterior Compartment of the Arm
Then, when it comes to the function, I actually want to show that to you because there are two general functions of the anterior compartment.
The first one would be flexion of the forearm, in other words, flexion of the elbow and you can see that here. So, when you’re flexing your forearm, people call this usually, “flexing your biceps.” You’re contracting your biceps but, you’re flexing your forearm or there’s flexion at the elbow joint.
Then, the second would be the flexion of the arm and that’s this motion right here. This is extension and this is flexion of the arm. Those are the two general functions of the anterior compartment, the muscles in the anterior compartment.
There is one additional function that I want to mention really quick, might as well. When we look at the coracobrachialis, there is one additional function because of the structure. That is going to be adduction so, bringing the arm towards the body. Adduction of the arm, that’s this movement right here.
All right so, that is the anterior compartment of the arm. Number one, the muscles are the biceps brachii, the coracobrachialis and the brachialis muscle. The innervation is done by the musculocutaneous nerve and the general functions will be flexion of the arm and flexion of the forearm and of course, you have that additional function of adduction by the coracobrachialis.
That’s pretty much it for this video. If you need more details on this like the origins and the insertions, you can come back to the website. This is video number 101. Come to Interactive-Biology.com/101, and you’ll find information on the origins, insertions, innervations, actions, and all that fun stuff.
As usual, you can just visit the website at Interactive-Biology.com for more videos like this and other resources to help make Biology fun. This is Leslie Samuel. That’s it for this video and I’ll see you on the next one.
|Biceps brachii||Long head: supraglenoid tubercle of the fossa.|
Short head: coracoid process of scapula.
|Radial tuberosity and bicipital aponeurosis to fascia of forearm.||Musculocutaneous nerve (C5, C6).||Both heads: weakly flex arm at shoulder. Also flexes and supinates forearm at elbow.|
|Coracobrachialis||Coracoid process of scapula.||Mid-medial surface of humerus.||Musculocutaneous nerve (C6, C7).||Flexes and adducts arm at shoulder.|
|Brachialis||Lower half of the front of the humerus, near the insertion of the deltoid muscle.||Tuberosity of the ulna and the rough depression on the anterior surface of the coronoid process of the ulna.||Musculocutaneous nerve and partly radial nerve.||Flexes the elbow joint.|