 It's going to be a demonstration of a rarely seen dissection, namely the platysma mass. Before I start describing about the platysma, I just wanted to draw your attention to two distractions or surgical artifacts that you may see. One is this tube that you see here. This is a ventricular peritoneal shunt, which was inserted in this cadaver and therefore we can see part of the tube here. The next point was this artifact that we see here. This was the place where the m-bomber had penetrated into the carotid artery to inject the embalming fluid. So disregard these two artifacts and focus on what I'm going to show about the platysma. We are going to zoom the camera in and out several times and I would like you to first take a good look at the platysma. And I'm tracing it down here. You can see these brown fibers here. These are the platysma fibers which are running on the right side of the neck. And similarly on the left side also, if you look very closely, we can see these brown fibers. And we can see they're going right from the chin all the way across the neck, across the clavicle and they go up to the upper part of the anterior chest wall. So these are the fibers of the platysma that we are talking about. The origin of the platysma, skin of the lateral neck, the subcutaneous tissue of the infraclavicular region and the deep fascia of the pectoralis major and the deltoid muscle which we have removed. One is to the lower part of the medagal and to the skin of the chin and the cheek, inter-digitating with the muscles there. Muscles of the chin are the depressor anguli oris. Under that we have the depressor labia inferioris, mentalis and risorias. So it inter-digitates with these muscles and with the opposite side platysma. So this is the right platysma and this is the left side platysma. And we can see that the platysma is absent exactly in the middle eye. The reason why the platysma is not present exactly in the midline that is over the larynx is to allow movements of the larynx during speech and deglutation. That is the reason why the platysma fibers diverge on either side of the midline. Nerve supply of the platysma, it is supplied by a branch from the facial nerve because it is a muscle of the second bronchial or the pharyngeal arch. This is the facial nerve that we can see inside the parotid gland which I have picked up. And here on this side we can see the branches from the facial nerve coming and supplying the platysma here on the right side. Another view of the same thing, cervical branch of the facial nerve. This cervical nerve it comes out from the cervical facial division of the facial nerve from inside the parotid gland. And this is the facial nerve which I have picked up inside the parotid gland and we can see the cervical branch coming and supplying the platysma. So the platysma, when it acts from above and pulls from above, it makes the skin of the neck tight or taut and that is the action which males use when they are shaving. Apart from that the platysma acts as a depressor of the mandible against resistance. In that respect it assists the suprahyoid muscles as an accessory muscle of mastication. So these are the actions in which exact plane is the platysma located. It is a muscle of the superficial fascia. The platysma is a subcutaneous muscle. It is located in the hypodermis that means it is located just under the skin and we have reflected the skin here to show you that the skin itself is not very thick and just under that we have a fat layer and almost interlacing with the fat and just under the fat is the layer of platysma. In fact we had to remove some of these fat globules from the surface of the platysma so therefore the platysma is located in the hypodermis. It is a muscle of the subcutaneous tissue of the skin. It is a part of the superficial fascia. So that brings me to an important concept here. In the anterior cervical region of the neck there is no investing layer of deep cervical fascia. So therefore the platysma forms a roof of the anterior cervical region and all the triangles in the anterior cervical region. Now let's come to a few important clinical correlations but let's say a person sustains a cut injury of the neck and he injures in branch of the facial nerve. This is the cervical division of the facial nerve which supplies the platysma and if this is injured then the platysma will get paralyzed on that side. In which case the skin of the neck will hang down and folds like that of an extremely old person and the person will not be able to make the skin tight. The next important clinical correlation is if there is any cut injury of the neck transversely. When we are repairing such a laceration of the neck we have to always suture the platysma as a separate layer and the same principle applies to any surgery of the neck. For example, thyroidectomy where we make curvilinear transverse incision. When we are closing it we are supposed to close the platysma as a separate layer. If we do not close the platysma as a separate layer and we suture only the skin then the contraction of the platysma from above and below will cause the scar to separate and it will become a wide thick and ugly scar. Therefore it is mandatory that the platysma should be sutured as a separate layer. So these are some of the points which I wanted to demonstrate about the platysma because it is a very rarely shown dissection and it is usually reflected along with the skin when the neck muscles are dissected. Thank you very much for watching. Dr. Sanjay Sanyal signing out. Mr. Kanderal is the camera person. If you have any questions or comments please put them in the comment section below. Have a nice day.