 going to be demonstration of the facial vessels and the facial nerve. This structure which I have lifted up here, this is the facial vein. The facial vein starts from the medial angle of the eye in this region and we can see a little bit of the origin of the facial vein if we see very closely. It starts as the angular vein by the union of two veins. The large supra orbital and medial to that is the small supra trochlear. They unite to form the angular vein and the angular vein descends down like this and it receives the superior palpable vein, the inferior palpable vein and in this region they also have communications with the superior and inferior of thalmic veins. Once the angular vein crosses the margin of the orbit and we can feel the margin of the orbit here. This is the margin of the orbit from here onwards it becomes known as facial vein and as it descends down it receives the branch from the nose called the external nasal vein and we can see a little bit of that here. Then it receives from the upper lip the superior labial vein it receives from the lower lip the inferior labial vein and it can also receive a branch from under the chin called the submental vein and we can see the submental vein here and then it continues down. Typically it should meet with a branch from the anterior division of the retromandibular vein which is here and then it forms a common facial vein and then the common facial vein then drains into the internal jugular vein deep to the sternocleidomastoid. Let me now draw your attention to this small correction here which is running inside this one. This is a very important communication this is referred to as a deep facial vein. A deep facial vein runs through the bugle pad of fat and it goes and it communicates with the teregoid venous plexus and this deep facial vein can be a source of spread of infection to the teregoid venous plexus and from there to the cavernous sinus and can lead to cavernous sinus thrombosis. So this is the deep facial vein that we have picked up here. Likewise as I was mentioning when it was coming down it received communications from the superior of thalmic vein and the inferior of thalmic vein. The superior of thalmic vein drains directly into the cavernous sinus. The inferior of thalmic vein drains into the teregoid venous plexus which in turn communicates with the cavernous sinus. So therefore if there is any infection on this region of the face then also infection can travel to the cavernous sinus and can produce cavernous sinus thrombosis. Cavernous sinus thrombosis is a particularly dangerous condition because cavernous sinus gives passage to ca3,4,v1,6 and sympathetic plexus. So therefore cavernous sinus thrombosis can lead to paralysis of one or more of these nerves and can also lead to a condition known as horner syndrome. So that brings me to the concept of what is known as the danger triangle of the face. So I put the skin back again here to trace out the danger triangle of the face for you. The apex of the triangle is at the root of the nose here and one margin of the triangle goes down along the side of the nose along the ale of the nose right up to the angle of the mouth. Approximately where the incision has been made and other triangle of the triangle goes like this. So this is the danger triangle of the face and we can draw three lines to represent the sides of the roots where the infection can travel. One line will be along the superior of thalmic vein like this. Another line will be along the inferior of thalmic vein like this. The third line will be the deep facial vein like this to show this is the deep facial vein again. Inferior of thalmic vein here, superior of thalmic vein here. So therefore any infection in this danger triangle should be taken very seriously because it can potentially lead to cavernous sinus thrombosis. So that is the importance of facial vein. Thank you very much for watching. If you have any questions or comments please put them in the comment section below. Dr. Sanjay Sanyal signing out. Anderson is the camera person. Have a nice day.