 Dr. Sanjeev Sangal, Professor Department Chair. In this video demonstration, I shall demonstrate the most important neurovascular structures which are located specifically in the dotted triangle of the neck. This structure, which I picked up with my instrument, this is the internal juggler vein, which arises from the juggler foramen at the base of the skull as the continuation of the sigmoid sinus. At its origin, there's a dilation called the superior bulb. And then it continues down on the lateral side of the artery. And it opens into the subclavian vein to form the brachioscephalic. So this is the internal juggler vein. At its termination, also, there is a dilation called the inferior bulb. And both at its superior bulb and inferior bulb, there is a valve called the superior and the inferior valve of the juggler vein. The juggler vein receives tributaries which correspond to the branches of the external carotid with the following exceptions. The first exception is this vein here, which is coming out from the penotent, the posterior auricular vein. This is not open into the internal juggler vein, instead it opens into the retromandicular vein. The second exception is the petrocell sinus, the distributory of the superior bulb of the internal juggler vein, which is not accompanied by an artery. And the third exception is the middle thyroid vein, which opens into the internal juggler vein. Apart from these exceptions, all the other tributaries accompany the branches of the external carotid artery. Let's mention a few important clinical correlations pertaining to the internal juggler vein. Canulation of the internal juggler vein is a very important procedure, which is done just lateral to the position of the common carotid artery. And this canulation is for the purposes of cardiac catheterization, specifically to the right chamber of the heart. We can use this method to check centrivenous pressure, CVP. We can record the right atrial pressure. We can record the indirect left atrial pressure, which is called the wedge pressure. And we can use it for intracardiac pacemaker placement and it is also used for rapid intravenous infusion. Incidentally, we can do the same procedures for the right subclavian vein also. Finally, in right heart failure, the intra-juggler vein is used to record the JVP, the juggler venous pulse, because it is a direct continuation of the right brachiocephalic at the right atrium and the superior vena cava. This is about the internal juggler vein. Now, let us come to the next important vascular structure that is the, this one which I picked up here. This is the common carotid artery, which is on the right side, it branch of the brachiocephalic trunk. It runs on the medial side of the internal juggler vein. And at the upper margin of the thyroid cartilage, it divides into an internal carotid, which I have lifted up with my instrument here, and the external carotid. The common carotid, where my instrument is pointing, is a common sight for feeling the central pulse. It is fed medial to the anterior border of the sternoclelo mastoid against the tubercle in the clasice process of the C6 vertebra called the carotid tubercle. The internal carotid, at its origin, there is this dilatation, we can see that. And that is known as the carotid sinus, which acts as a baroreceptor. And there's a carotid sinus reflex, which helps to control the blood pressure. The internal carotid artery, as it climbs up, it enters into the pitous part of the temporal bone and travels in the carotid canal, and it supplies the brain by means of the anterior circulation. These are a special sequence of magnetic resonance angiogram, which I refer to as a three-dimensional time of flight spoiled gradient recall echo acquisition images. These clearly show the two internal carotid arteries. In order to understand them best, just imagine that the head is slowly spinning in a clockwise direction. Internal carotid artery, which has been lifted up by my instrument, is a very common site of atherosclerosis and can lead to what is known as cerebral vascular accident or in common language stroke. And when we have such a situation, we have to do what is known as transliminal angioplasty, that is to remove the obstructing atherometous plaque. If it is a large segment, then we may have to do what is known as a carotid end artery rectomy. Atherometous plaque removal by means of an open surgery is called end artery rectomy, while when it is done intra-luminally, it is known as angioplasty. Now, let's come to the external carotid artery. Though it's called external carotid artery, it is actually on the inner side of the internal carotid artery. The reason why it's called external carotid artery is because it supplies to all the structures outside the skull. Let's take a look at the branches of the external carotid artery. And for that, I have lifted up the external carotid artery. And external carotid artery has got the following branches. Three branches anteriorly. This is the first branch, the superior thyroid artery, which supplies the thyroid and it also gives a superior laryngeal artery. The second branch is the lingual artery. The lingual artery forms a loop and then it enters into the tongue, going deep to the hyoglossus. And it is crossed by the hypoglossal nerve. The third branch is this one, which I picked up. This is the facial artery. And we can see the facial artery is going under the stability of the gastric and the stylohyoid and it is entering into the submandibular triangle. The facial artery then grooves the submandibular salivary gland and then comes into the face. So these are three branches which go from below up anteriorly. Now let's take a look at the two posterior branches of the external carotid artery. The first of the posterior branches, this one. This is the occipital artery. This runs posteriorly and it runs deep just under the mastoid process and there it forms a groove and then it comes to the scalp and supplies the posterior part of the scalp. To understand the next branch, we have now come into the intra-temporal fossa and I am holding up the external carotid artery just before it enters the intra-temporal fossa. It gives off this branch here, which I have lifted up. And we can see it is entering into the carotid gland. This is the posterior auricular artery. So therefore the posterior auricular artery is on the upper side of the posterior belly of the gastric and the occipital artery is on the lower side of the posterior belly of the gastric. The posterior auricular artery also supplies the little bit behind the ear. So these are the two branches going posteriorly and finally, if I were to lift up the external carotid artery, we can see a deep artery going inside, medially. This is the ascending pharyngeal artery. So these are the six branches of the external carotid artery and finally, once we reach the intra-temporal fossa, this is the termination of the external carotid artery and inside the carotid gland, which has been split open here, the external carotid artery divides into its two terminal divisions. One division, the larger one goes into the intra-temporal fossa and that is known as the maxillary artery and the smaller terminal division is this one which is known as the superficial temporal artery which we can see running in front of the triggers of the ear and it is running in a tortuous fashion over the temporal region and supplies the scalp by means of the frontal and the temporal branches. The superficial temporal artery position can be felt over the zygomatic arch in front of the triggers of the ear. Thank you for watching. Stay tuned for the next video.