 Good day everybody. This is Dr. Sanjeev Sanyal, Professor Department Chair. So this is going to be a demonstration of the structures on the right half of the face. We have completely decided out the supine cadaver. I'm standing on the right side. So first let's take a look at the muscles of facial expression. The thing about the muscles of facial expression are they are all derived from the second brankel arch and they are all supplied by branches of the facial nerve. So therefore though they are skeletal muscles, their texture is different and they do not have bony attachments on either side. One side may be having a bony attachment, the other side will be attached to the skin and they will be intermingled with fat and fascia. So therefore they are very fine structures and that's why they're called muscles of facial expression. So let's start off from the top and see what are the muscles that we can see here. First of all, we can see this muscle descending down. This is the alarnazalis. And if you look very carefully, we can see that there are some fibers which are going towards the ale of the nose. So therefore this is the alarnazalis and the rest of the muscle is the libator labiae superioris. So therefore the two together are called libator labiae superioris alec nasi. Then we have the next muscle here. This is the zygomaticus minor. Then we have this muscle here. This is a remnant of the zygomaticus major, which I'm going to come back again in a little while. Before I go any further down, let me just finish off this muscle here on the top. We can see this muscle here. This is the procerus muscle. This is the one which is responsible for producing horizontal wrinkles on the root of the nose. Then we have these muscle fibers. This is the corrugator super cli. And intermingle with the corrugator super cli and there's muscles around the eye. We have this muscle here. This is the frontalis muscle. This frontalis muscle is the one which gets attached to this ratio here. This is the galli aponeurotica. This circular muscle fibers that we can see here on upper eyelid and on the lower eyelid. These are the orbicularis oculi. The ones which are closer to the eyelid, they are the palpipar part and the ones which are more peripheral, they are the orbital part. And we can see them very clearly here. These are the ones which are responsible for closure of the eye. To continue further, as I've already mentioned, this is the zygomaticus major, the remnant of it. Deep down, we can see this muscle here. This is the libator anguli oris. Now this zygomaticus major, the libator anguli oris and the libator libis superioris, they all get attached to one fibromuscular condensation where my finger is pointing right now. This is called the modulus. The modulus is a fibromuscular cartwheel shaped structure, which is located approximately one centimeter lateral to the angle of the mouth. And attached to this modulus are six muscles. Three from above and three from below. The three from above are the libator libis superioris, the libator anguli oris and the zygomaticus major. The three from below are this muscle here, this curved muscle that we can see here. This is the depressor anguli oris. Then we have this muscle. We can see this going laterally. This is the risorius. Then we have the depressor labi inferioris and we can see this muscle here. This is the depressor labi inferioris. So three muscles from top, three muscles from below. And finally, we have a muscle coming from the median side and we can see a little bit of that here. This is the orbicularis and from the lateral side, we have this muscle here. This is the buccinator. The buccinator is a very unique muscle and we can see the parotid duct, the stenceless duct is piercing through the buccinator before it opens opposite the crown of the upper second molar tooth. This buccinator is the one which is responsible for blowing out the cheek. This takes origin from the terecomandibular raffae, from the maxilla, from the mandible and the fibers. They go anterior medially and they get inserted onto the modulus. So these are the total eight muscles, three from above, three from below, one from the median side, one from the lateral side, which are inserted onto this modulus. Having mentioned that, I will draw your attention to this big muscle that we can see here. This is not a muscle of facial expression. This is a muscle of mastication and this is the meseter muscle and we can see it is taking origin from the zygomatic arch. The fibers are very strong and they are covered by this aponeurotic sheet and they get inserted onto the meseter tuberosity on the lateral side of the angle of the mandible. This is responsible for tight closure of the jaw and the superficial fibers are responsible for protrusion of the mandible. And finally we can see a few muscle fibers here. These are the remnants of the platysma, which takes origin from the chest and the fibers they go up and they interdigitate with the muscles of the chin and with the opposite side and they are responsible for tensing the skin of the neck as well as depressing the mandible. Having mentioned these muscles of facial expression, which are all supplied by branches of facial nerve and we can show you some branches of facial nerve here. This is one branch of facial nerve, this is another branch of facial nerve and we can see it is supplying the platysma. They are all supplied by branches of facial nerve which comes through the parotid gland and we can see some of these branches here. Now let me draw your attention to the neurovascular structures that are visible in this particular dissection. So let's start from below. First of all we can see this torturous structure here. This is the facial artery. The facial artery is the branch from the external parotid artery from the neck. And as it goes up it makes a loop under the mandible and it makes a groove on this gland here. This is the submandibular salivary gland and then it follows a torturous pattern on the side of the face. It enters the face just anterior to the anterior border of the mandible and here against the lower border of the body of the mandible we can feel the pulsation. So this is the exact location of the pulsation of the facial artery and then the facial artery forms a torturous course. It intermeshes within the muscle fibres and with the fat and fascia and it finishes at the angle of the eye as the angular artery. So we can see a part of the facial artery here and we can see one of the branches here. It gives branches to the sub-mental artery, to the inferior labial, superior labial, lateral nasal, angular. So these are the essential branches of the facial artery. The next structure that I would draw your attention to is this one here. This is the facial vein. The facial vein starts as the angular vein here by the union of the supra-trochlear and the supra-orbital vein. And we can see one of the structures which are visible here at the root of the nose, this one. This angular vein, when it crosses the low margin of the orbit, it becomes known as the facial vein. So this is the continuation of the facial vein. And this is roughly parallel to the facial artery and as it goes down, it receives tributaries which correspond to the branches of the facial artery, namely an external nasal vein, a superior labial vein, inferior labial vein and the sub-mental vein. It receives communications. I will draw your attention to one particular vein which it is receiving and that is this one here. This is the deep facial vein. The deep facial vein comes through the buccinator muscle. This deep facial vein is the one which is responsible for carrying infection from the danger triangle of the face to the teregoid venous plexus. I shall come to the danger triangle of the face just in a little while. And then the facial vein, when it crosses the angle of the mandible, it comes to the neck. It is ideally supposed to unite with the anterior division of the retro mandibular vein, but in this case it is not uniting and then it forms what is known as a common facial vein which then opens into the internal jugular vein, which we cannot see in this particular dissection. That brings me to something called the danger triangle of the face. What is this danger triangle? This is a triangular area which starts from the root of the nose. It goes obliquely like this till the angle of the mouth on both the sides. This whole region is called the danger triangle of the face and we have made our skin incision corresponding to the danger triangle of the face. Any infection in the danger triangle of the face can potentially cause cavernous sinus thrombosis and how does it do so? Connections from here will go through the superior of thalmic vein. Connections from here will go through the inferior of thalmic vein and connections from here middle of the face will go through the deep facial vein. Any of these can communicate with the cavernous sinus either directly or indirectly through the teregoid venous plexus and can produce cavernous sinus thrombosis which is a potentially serious condition because that will produce what is known as cavernous sinus syndrome and can lead to injury to CN3, V1, V2 and CN6 and the sympathetic plexus and lead to what is known as Horner syndrome. So these are the importance of this facial venous drainage. Before I conclude I need to show you some other arteries which are visible on the face. We are in the upper portion of the parotid gland and we can see these structures here. This is the facial nerve which I had mentioned earlier. We can see the facial nerve and it's giving two trunks. One upper division, one lower division. Upper division is the temporal facial division which divides into a temporal and a psychomatic branch and the lower one is the cervical facial division which gives the buccal marginal mandibular and cervical branch and we can see the two divisions here. This is the type 1 division. We can see this artery here. This is the superficial temporal artery which is the smaller terminal division of the external parotid artery dividing into maxillary and superficial temporal. Then we can see this vein here. This is the superficial temporal vein and we can see this nerve here. This is the auricular temporal nerve. These three structures they travel in this superficial temporal fascia and we can see this tortuous artery here. This is the continuation of the superficial temporal artery and they supply the skin of the temporal region. So these are the structures which I wanted to show you on the face and before I conclude I need to show you one more structure. This is the great auricular nerve. The great auricular nerve comes from the cervical plexus and it goes and supplies the parotid sheath. It also supplies a little bit of the skin over the parotid region as well as the sweat glands over the skin of the parotid region in this here. So therefore if there is an injury of the trigeminal nerve this is the portion of the space which will be spared from loss of sensation. And talking about trigeminal nerve brings me to this nerve here that we can see. This is the continuation of the interorbital nerve which comes through the interorbital foremen and it supplies the skin of the middle one third of the face. So these are all the structures that I wanted to show you in a dissection of the face. The arteries, veins, nerves and the muscles of facial expression. Thank you very much for watching. Dr. Sanjeev Sanyam signing out. Solomon is the camera person. If you have any questions or comments please put them in the comment section below. Have a nice day. Please like and subscribe.