In this video, Leslie focuses on the different gateways for specific nerves and arteries from the anterior scapular region to the posterior scapular region namely the suprascapular notch, quadrangular space, triangular space, and triangular interval. Included is the identification of the borders and contents of each of these spaces.
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. In this video, I’m going to be talking about the gateways to the posterior scapular region and the contents that we find there. What we’re basically talking about would be some openings by which we can get from the anterior scapular region to the posterior scapular region.
Basically, what is happeing is we have some nerves that are coming off the brachial plexus. We have arteries that are coming off the axillary artery. We want to get to the back, to the posterior scapular region so that, we can innervate the muscles that are found behind there and also supply the blood that is necessary for them to function. That’s what we’re going to talk about. Let’s get right into it.
The first one that we’re going to talk about is called the suprascapular foramen. Anytime we say a ‘foramen’ we’re talking about an opening. What we have here, this is a picture of the anterior view of the scapula. What we have here , we see this little notch that we call the scapular notch. You can see it here. From the posterior view, you can see it here also.
We have that notch. What we have traversing that notch going across from one end to the next, we have a ligament that we call the transverse scapular ligament (let’s draw that in right here). That is the first gateway that we have to get to the posterior scapular region and that is called the suprascapular foramen. This opening that we have right here, that we have right there, that is what we are referring to.
In terms of the content of that foramen, the contents that we have, one particular thing would be the suprascapular nerve. We have the suprascapular nerve (let’s do that in red) that’s basically coming through that foramen to get to the posterior scapular region. What is interesting is we have a suprascapular nerve, and we have a suprascapular artery. What we find is that the nerve goes through that foramen. It goes under the transverse scapular ligament in other words, and the artery goes above (let’s do that in blue). We have the artery that’s going above that ligament.
An easy way to remember that is, “The army goes over the bridge. The navy goes under the bridge.” The artery goes over the transverse scapular ligament and the nerve goes under the transverse scapular ligament. That’s the first gateway, the suprascapular foramen that has the suprascapular nerve going through that foramen under the transverse scapular ligament and the suprascapular artery that goes over or superior to that transverse scapular ligament.
Then, we have three other gateways that are made up of similar structures. You can see them right here. We have the (I’m going to write it over here) quadrangular space and then, we have the triangular space and the triangular interval.
There’s a very easy way of going over this so that, you can remember it. What I do when I studied this, this is how I remembered it. I took my index finger and my middle finger of both hands.
Let’s say I’m taking my right hand and I’m going to put my index finger right here and my middle finger right here. You can just do that. Put it in front of you right now. You’ll see it’s kind of like you’re putting up a peace sign but, on the side.
Then, on your left side you’re going to take your left middle finger and put it here and your left index finger and put it here. Those fingers all represent certain structures. Your right middle finger is going to represent teres minor, which is what we’re seeing here. Your right index finger is teres major. Your left middle finger is going to be the humerus and your left index finger is going to be the long head of the triceps.
When we look at these different spaces, we can easily see what the borders are. The quadrangular space is right here and it makes sense because it has four sides. So, we call it the QUADrangular space. When I look at the borders, the superior border is going to be teres minor. The inferior border is teres major. The medial border is going to be the long head of the triceps. The lateral border is the neck of the humerus.
Alright, so you can take your fingers, put them in this arrangement and then, you can quiz yourself and go over and over and you’ll get it really clearly.
Then, when we look at the triangular space. We can see here, this is the triangular space. The borders of the triangular space are the superior border would be teres minor, inferior border is teres major, and the lateral border is the long head of the triceps.
Then, the triangular interval, you can see that right here. This is going to be a little different. The superior border is the teres major muscle. The medial border is the long head of the triceps. The lateral border, it looks as if it’s the muscle but it’s actually the shaft of the humerus.
So, we have quadrangular space, triangular space and triangular interval.
Now, for the contents of those gateways.
For the quadrangular space, the two things that we have going through that space is number one, the posterior humeral circumflex artery. So, I’m just going to write PHC, that’s not an official abbreviation, the “posterior humeral circumflex” artery coming off of the axillary artery, basically coming around and going through that opening. That’s the posterior humeral circumflex artery.
Also, we have the axillary nerve that’s coming through there and it’s coming through there to then innervate the deltiod muscle and teres minor and so on. But, for right now, all you need to know is coming through the quadrangular space, we have the posterior humeral circumflex artery and the axillary nerve.
Then, we only have one structure, one thing that’s coming through the triangular space. That is the circumflex scapular artery. The circumflex scapular artery is coming through that triangular space.
Then lastly, through the triangular interval which is down here, we have two things. We have the radial nerve and the deep brachial artery.
So, once again, through the quadrangular space right here, we have the posterior humeral circumflex (PHC) artery and we also have the axillary nerve. Coming through the triangular space, we have the circumflex scapular artery. Then, through the triangular interval, we have the radial nerve and the deep brachial artery.
Alright, so let’s quiz ourselves really quick. As usual, you can turn down the volume and follow along with me.
The name of the gateway would be suprascapular foramen which is right here. The ligament would be the transverse scapular ligament that extends across. Under the ligament we have the suprascapular nerve and above or over the ligament, we have the suprascapular artery.
Then, moving on here we have the quadrangular space. The borders would be, the superior border is teres minor. Inferior border is teres major. Medial border is long head of the triceps. Lateral border would be the neck of the humerus. The contents would be posterior humeral circumflex artery and axillary nerve.
Then here, we have the triangular space. The borders would be, the superior border is teres minor; inferior border, teres major; lateral border is going to be the long head of the triceps. The contents would only be the circumflex scapular artery.
Then, we have the triangular interval. The borders, superior border would be teres major. Lateral border would be the shaft of the humerus, and the medial border would be the long head of the triceps. The contents would be the radial nerve and the deep brachial artery.
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But, more importantly, make sure to come back to the website at interactive-biology.com for more Biology videos and other resources to help make Biology fun. This is Leslie Samuel. That’s it for this video and I’ll see you in the next one.