 Good day everybody. This is Dr. Sanjay Sanayal, Professor Department Chair. So this is going to be a demonstration of certain triangles of the neck. So this is a supine cadaver. We are standing on the right side. Camera person is also on the right side. My assistant is also on the right side. And we have dissected out the right side of the face, the neck, and we have opened up the thoracic cavity. So the first demonstration is going to be in this triangular region that you see here. I'll put back the sternofleomastoid in its place. This is the retracted sternofleomastoid that I put back in place. And I'll draw your attention to this triangle here. This is the sternofleomastoid. We have removed the manor brimsterni. This muscle here, this is the superior belly of omohioid. And this muscle here, this is the posterior belly of diagestric. So therefore this is the carotid triangle. And you have understood clearly why it's called the carotid triangle. Because this is where the common carotid artery is located. And this is bifurcating into an external and internal carotid artery. So therefore this is going to be the main focus of our demonstration in this particular one. So before we proceed any further, let me give you a quick orientation of the other structures which are visible. So that we can get the clear picture. This is the right side of the face. We can see this gland here. This is the carotid gland. And we can see this vein coming out from here. This is the retromandibular vein. And it's opening into the internal jugular vein. This is the carotid duct. And it's opening piercing through the vaccinator. And it's opening inside the mouth. This muscle that we see here, this is the right misciter muscle. This is the body of the mandible. This is the angle of the mandible. This is the risorius muscle. This is the little bit of the sub-mandible gland which is peeping out. Which is going to be a demonstration in another dissection video. This is the posterior belly of diagestric. This is the anterior belly of diagestric. As I mentioned, this is the sternocleidomastoid. This is the superior belly of omohiat. This is the inferior belly of omohiat. And the facial sling is in between the two bellies here. This is the combined sternohioid. And under that is the sternothyroid and the thyroidohioid. So these are the muscles which are visible and the structures which are visible. Now what I'm going to do is I'm going to retract the sternocleidomastoid. And that's what I'm doing right now. And my assistant is going to push it back behind the ear. So what are the structures that we see here? The most important content of this triangle is the common carotid artery. The common carotid artery divides the level of the superior thyroid notch. Approximately. And it divides into this and this branch and we can see them clearly here. This is the external carotid artery. This is the external carotid artery which I have lifted up here. And the other one, this is the internal carotid artery. And in between the two of them, there is going to be a small fibro structure here which is composed of special cells. That's called the chemoleceptor. That's called the peripheral chemoleceptor, the carotid body. This dilatation that we see here, this is the carotid sinus. The carotid sinus, the carotid body are both supplied by branches of the glossopharyngeal which we cannot see. This one carotid sinus acts as a paroreceptor. Carotid body acts as a peripheral chemoreceptor. Further demonstration of the internal carotid artery is not possible because it goes deep and it enters into the carotid canal in the pace of the skull. So we shall focus our discussion on the branches of the external carotid artery and its related structures. So this is the external carotid artery as I mentioned just now. And I have lifted it up and all of you can see it very clearly here. The external carotid artery is called external carotid artery because it supplies all the structures with exceptions of course. It supplies structures outside the skull. So therefore let's take a look at the branches. Typically there should be six branches of the external carotid artery before the terminal branches. So let's take a look at the branches that we can see in this dissection. First of all, let's take a look at the first branch that we can see. The textbook describes it as one branch going immediately two branches going posteriorly and three branches going anteriorly. So let's take a look at the branch that is visible to us. The branch going anteriorly. The first one is this one here. This is the superior carotid artery. And we can see when I retract this muscle the sternohyroid and the sternothyroid we can see this is the carotid gland. And we can see that this is going to the carotid gland. So therefore this is the superior carotid artery and it is going to be accompanied by the external laryngeal nerve. This one which supplies the cricothyroid muscle. This is the cricothyroid. That's the first branch that we can see here. The next branch that we can see here is this one here. We can see this branch. In this particular cadaver this is a combined branch and from here we can see this artery coming out. This is the lingual artery. And from there we can see yet another artery that is the fascial artery. So normally the fascial artery and the lingual artery are supposed to arise separately as per the textbook description but in this case it is arising from a common stem. The lingual artery and then the fascial artery. And I will draw your attention to a few special things. When I retract this you can see that both the lingual artery and the fascial artery they make a loop up like that. And running in front of the loop is this nerve here. This is a very important relationship. This nerve is the hypoglossal nerve. Let's retract the hypoglossal nerve now. The lingual artery it goes deep to the hyoglossal muscle which is here and it divides into dorsal lingual, deep lingual and sublingual branches which supply the tongue. The fascial artery this also makes an upward loop which goes under the body of the mandible and then it comes out. And we can see it coming out here when I bring out the submandibular gland. You can see this artery coming out here. This is the fascial artery. It goes under the mandible and then comes out. It makes a deep groove on the posterior aspect of the submandibular gland and then it goes to the face. So that is the fascial artery. So we have seen three branches just now. We have seen the superior thyroid, we have seen the lingual, we have seen the fascial. Now I will draw your attention to some other branches. So for that we will retract this here. This is the posterior belly of the digastric as I told you just now. So I will draw your attention to this artery here. This is the main common carotid, right external carotid and we can see this branch coming out. This is the occipital artery which runs under the posterior belly of the digastric. And if you look further deep you will find this branch here. This is the posterior auricular artery. So these are the two branches which go posteriorly and if you look further inside, deep inside we will see yet one more branch. This is the ascending pharyngeal artery which is rather deep and it runs straight up and supplies the pharynx. So therefore the six branches that we saw are the superior thyroid, the lingual, the fascial, the posterior auricular occipital. And finally after it has supplied all these, the main external carotid artery. It goes under the posterior belly of the digastric and the stylohyoid and we can see that here. And it continues and it enters into the carotid gland that also we can see. And then when it is about to enter the infratemporal fossa, it divides into larger terminal division. That is a maxillary artery which goes into the infratemporal fossa and the superficial terminal branch which runs here as the superficial temporal artery. So these are the full course of the external carotid artery. The next structure I will draw your attention to is this vein here. This is the internal jugular vein and as I told you earlier in this case there is a anatomical variation. The retromandibular vein is this one here which is coming through the carotid gland and it is dividing into an anterior division and a posterior division. The anterior division becomes a common facial vein. The posterior division is supposed to unite with the posterior auricular vein and form the external jugular vein in a normal circumstance. But in this particular case we can see that the retromandibular is opening into the internal jugular vein itself. So that is also one of the contents in this particular case of the carotid triangle. And the third structure that we can see here is this big nerve which runs in the carotid sheath posterior to these two structures and you have guessed it already. This is the vegas nerve. So these are the structures that we can see in the carotid triangle. The floor of the carotid triangle is formed by the pre tracheal fascia. Specifically the muscular component of the pre tracheal fascia and the roof which we have removed is composed of the plettissima muscle. So these are the structures that we can see in the carotid triangle. And before I conclude, when we want to palpate the central pulse of a person who is lying unconscious on the floor, you would have seen people trying to palpate the central pulse. That location of the central pulsation is just medial to the medial border, anterior border of the sternocleomastoid just under the superior belly of omohiod exactly in this location where my instrument is pointing right now. This is the place where we palpate for the central carotid pulse to see if a person is alive or not. And this is the place where we palpate the common carotid artery. The common carotid artery is used as a root for many diagnostic and therapeutic procedures. So that's all for now in this particular section of the carotid triangle. Thank you very much for watching. Dr. Sanjeev Sanyal signing out. We have a person, our MD1 students. If you have any questions or comments, please put them in the comment section below. Have a nice day. Please like and subscribe.