 This is a demonstration of the muscles of facial expression as much as we could dissect them and take them out in this particular specimen here. So, let us start from the top, right in the front on the frontal region we have this muscle here on the right side and the same muscle on the left side. This is the frontalis muscle, the frontalis muscle takes origin from the galey upper neurotica and it gets inserted on to the subcutaneous tissue of the forehead and the eyebrow this side also and therefore, when this muscle contracts it produces horizontal wrinkles on the forehead that is the first muscle. The second muscle that we can see here we can see more on the left side, but not so much on the right side is this muscle here, this muscle, this is the prosthetic muscle it gets inserted on to the skin of the bridge of the nose and this when it contracts it produces the what is called the disdainful expression of the face that is the next muscle that we can see here. The third muscle that we can see here we can see more on the right side are these circular fibres, we can see the circular fibres going around the eye and then they are going and coming on to the inferior aspect. These circular fibres these are the orbicularis oculi fibres, now the orbicularis oculi fibres are divided into two parts here we can see, one set of fibres are on the eyelid itself this and on the lower eyelid these, these are the palpable part and these are responsible for gentle closure of eyelid and then surrounding them we have these peripheral fibres which are starting from here and they are going all the way around the supra orbital margin and inferiorly also we can see they are starting from here and they are going all the way around and we can see them clearly here. These are the orbital fibres of the orbicularis oculi and when they contract they are responsible for tight closure of eyelid that is the next muscle that we can see here the orbicularis oculi. Now let us focus on yet one more muscle and we can see that muscle here, we have lifted it up this is the zygomaticus major, it is taking origin from the zygomatic bone and gets inserted on to a structure called the fibromuscular condensation of the face also known as the modulis which I shall describe just now. So, this is the zygomaticus major when one side contracts it elevates the angle of the mouth on that side and it produces a sneery expression, but when both the sides contract simultaneously they produce a smile or a grinning expression that is about the zygomaticus major that is the next muscle that we can see here. If we look closely on the medial angle of the eye we can see some muscle fibres coming down here, this are the complex muscle very small but very complex and we can see the fibres here, this is the libator labiae superioris alec nasi. So, some of the fibres are attached to the upper lip and some of the fibres are attached to the ala of the nose that is why it is got this complex name. This libator labiae superioris alec nasi it also produces a sneery expression and it also produces flaring of the ala of the nose as when the person is exerting or when the person is angry. So, this is about this muscle that we can see a few fibres. Let us come further down we see when I have lifted up the skin of the lower lip we can see some fibres here, these are the fibres of the orbicularis aureus, the orbicularis aureus goes all the way around the upper and the lower lip we have lifted up only one side to show you fibres of the orbicularis aureus, they also get inserted onto the modulus which I shall describe just now. Then if you look very closely we will see some fibres branching out like this in a fan shaped fashion and my instrument is tracing them. These are the depressor anguli aureus muscle, depressor anguli aureus which also gets attached to the modulus here. Under the depressor anguli aureus will be the labiae inferioris, the risorius and further deep down will be the mentalis, the chin muscles. The next muscle that we can see here is this muscle part of which we have cut here and we can see the fibres coming down and we can see the fibres here also. This is the platysma, the platysma actually interlaces with fibres in the chin and it goes all the way down across the neck and it gets inserted onto the deep fascia of the pectoral region and the deltoid region so this is an extensive muscle this also is considered as a muscle of the face and neck. The thing about all these muscles which I have described are that they are all derived from the muscles of the second brachial arch therefore they are all supplied by branches of the facial nerve and we can see the facial nerve part of it visible here as it is coming out from the perotid gland. So this facial nerve is the one which supplies all these muscles of facial expression. So now let me come to the modulus which I was talking about. The modulus is a fibromuscular condensation which is approximately 10 millimeters from the angle of the mouth lateral to the angle of the mouth that means approximately here and my finger has lifted it up here and picked it up here. So this is the region of the modulus of the face. The modulus is shaped like a cartwheel and it has got 8 muscles attaching to it, 3 from the top, 3 from the bottom, 1 from the lateral aspect and 1 from the medial aspect. So what are the 3 muscles from the top? One I have already shown you, zygomandicus major. Other 2 muscles are the libator anguli oris and the libator labiae superioris which is located under the skin of the aquarumid. So these are the 3 muscles from the top. The muscles which are attached to the modulus from below are 1 the muscle which I showed just now, this is the depressor anguli oris. Other than that we have the depressor labiae inferioris and we have the risorius. So these are the 3 muscles which are attached to the modulus from the inferior aspect and we have a muscle which is also coming from the lateral aspect that is this muscle here that is the buccinator muscle and coming from the medial aspect we have the circular muscle around the lip which we mentioned as the articularis oris. So there were 3 from the top, 3 from below, 1 from the lateral aspect and 1 from the medial aspect. These 8 muscles constitute the modulus. When there is a facial adhesive, the modulus is not supported by these muscles and therefore it drops out and that is what produces drooping of the angle of the mouth. We can see one muscle here. I am mentioning it just because it is present but it is not a muscle of facial expression and this muscle is the mesinter muscle. This is actually a muscle of mastication and it is not supplied by the facial nerve. It is just mentioned to complete the picture. Let me mention a few quick words about the nerve supply and the clinical correlation between these muscles. As I mentioned this is the facial nerve as it is emerging from the parotid gland here and as it emerges it divides into 2 principal trunks the temporal facial and the cervical facial. The temporal facial gives a temporal branch and a zygomatic branch which supplies the muscles of the upper half of the face and then we have the cervical facial and the cervical facial gives 3 other branches the buckle, the marginal mandibular and cervical. So these are the 5 branches of the facial nerve we supply all the muscles of facial expression. So therefore when the frontalis muscle is paralyzed then the patient will not be able to wrinkle his forehead. When the orbicularis oculi muscles are paralyzed then the person will not be able to close his eye and when he goes to sleep his eyeballs roll up which is known as Bell's Phenomenon and additionally there will be drooping of the lower lid and there will be overflow of tears which is known as Epifuria. There will be flattening of this groove here on the side of the nose and the mouth and that is the nasolabial sulcus that will be flattened and as I mentioned a little while back the modulus will drop down so therefore there will be drooping of the angle of the mouth. When patient has drink liquid the liquid will dribble out from that side of the mouth and saliva will also dribble out. Patient will not be able to retain food on that side of the cheek because of the paralysis of the buccinator and he will not be able to blow out his cheek. He will not be able to pucker his chin on that side because of the paralysis of the mentalist and he will not be able to make the skin of his neck taut like for example as they do in shaving during shaving because of the paralysis of the pletisma muscle and the skin of the neck will hang down in folds because of the paralysis of the same muscle. So these will be some of the manifestations which are seen in facial nerve palsy the lower motor neuron facial palsy and the most common type of facial palsy that is seen is during parotid surgery when a facial nerve is injured. Other example of facial palsy is when it is inflamed in the facial canal in the skull and that is known as Bell's paralysis. So these are some of the clinical manifestations of facial nerve paralysis. That's all for now. 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. Have a nice day.