 Good day everybody. Dr. Sanjay Sanyal, Professor Department Chair. This is the Subang Kedever. I am standing on the right side of the Kedever and the camera person is towards the head end. This is going to be a demonstration of the scalp, the surgical implications of the scalp. We have incised the scalp here and we have reflected this layer that we can see in front of us. This layer that I have reflected is called the scalp proper. What are the components of the scalp proper? We have further subdivided that layer and you can see it here. This layer that we have picked up is the skin. With its usual hair follicles, sebaceous glands and sweat glands and everything else. Now if you were to take a look at the deeper surface of the skin, we find multiple dense short fibres which we have cut. This is a very extensive dissection that we have done and we can see the other short fibres on this side also. So this layer is called the connective tissue, dense connective tissue layer. This layer acts like a cement, like a glue which holds the next layer and that is this one here. This is called the aponeurotic layer. Also called the gallia aponeurotica. And these three layers together constitute the scalp proper and this is how they were fused. And if you were to take a look at the deep surface of the gallia, this is how it looks like. Let's focus on this gallia aponeurotica. This gallia aponeurotica is actually strictly speaking an aponeurosis only in the middle of the scalp. Antiretally it becomes fleshy and we can see the fibres of the muscle here. This is the frontalis muscle which we have picked up. And these frontalis muscle fibres, they take origin from the gallia aponeurotica and they get inserted onto the subcutaneous tissue of the eyebrow. And they are the ones which are responsible for wrinkling the forehead. Further posteriori which we cannot see, the same gallia aponeurotica will give attachment to another muscle and that is called occipitalis muscle. Which will take origin from the superior nuclei and get inserted onto the gallia aponeurotica. So when the occipitalis muscle contracts, it tensils the gallia aponeurotica and therefore it increases the functionality of the frontalis muscle. What happens to the gallia as we go laterally? As we move laterally, the gallia aponeurotica becomes thin and we can see here. It has become very thin in this portion. And further laterally, it is no more gallia aponeurotica, instead it is called temporal parietal fascia. And this temporal parietal fascia in some textbooks it is called as the superficial temporal fascia. It covers the temporalis region and the deep temporal fascia. And running in this superficial temporal fascia or the temporal parietal fascia, we have these neurovascular structures. We can see the cut end of one of those and we can see the cut end of the others. These are the superficial temporal artery, the superficial temporal vein and the auricular temporal neuron. So this is the lateral extension of the gallia aponeurotica. And further laterally, this temporal parietal fascia gets attached to the zygomatic arch. So therefore, this gallia aponeurotica is attached posteriorly to the superior nuclei through the occipitalis muscle. Laterally it is attached to the zygomatic arch, but in front it is not attached because the frontalis muscle gets attached only to the subcutaneous tissue. This point has to be remembered. Now let me reflect this layer. Then we come to this next layer and which we have reflected up here. This is the periosteum of the skull bone. And after that we have the skull itself. This periosteum also requires a few explanations. This periosteum covers the vault of the skull. It continues through the foremen and continues on to the interior of the skull as the endosteum. It also gets attached to the sutural membranes between the bones. And this same periosteum continues on to the base of the skull. The periosteum on the vault of the skull is not as tightly attached as it is in the base of the skull. Therefore, if it is in a fracture of the base of the skull, the periosteum is more likely to tear and can produce CSF rhinorea or CSF autorea. This periosteum is essential for the survival of the skull because it gets nutrition. The skull gets nutrition from the periosteum. Now let's come to some clinical correlations pertaining to the layers of the scalp. Most of the clinical correlations pertain to this layer. This layer where I put my finger here, or the layer under the aponeurosis above the periosteum. This layer was actually filled with very loose areola tissue which we have dissected out. And that layer is called the loose areola tissue layer. And this layer has got the maximum number of clinical correlations. This layer is very poorly vascularized. So therefore, infection, if it occurs, it spreads very rapidly because there is not much immunity. There are blood vessels which are passing through this layer. They are called emissary veins. And those emissary veins can get infected and they can lead to intracranial venous sinus thrombosis. If there is any blunt trauma to the skull, blood can track in this loose areola tissue layer and it can track to the skin around the eyelid. What is known as black eye or the raccoon eye. This is a picture of a child with black eye also called periorbital echemosis and the incense shows raccoon eyes. This layer can get completely evulsed and that is for abortion of the scalp. This typically occurs when people with long hair are operating near machinery and the hair gets caught in the machinery and the whole scalp gets evulsed. So therefore, the loose areola tissue layer is clinically significant from at least four different perspectives. Spread of infection, intracranial sinus thrombosis, extravascular blood, abortion of the scalp. In its favor, we can say that the loose areola tissue has got one surgical advantage. If there is a mild trauma to the skull, then the loose areola tissue because it is mobile, it absorbs part of the blow and therefore it prevents the blow from being transmitted to the skull itself. So these are the important clinical correlations pertaining to the loose areola tissue layer. A quick word about this temporal parietal fascia. In surgical textbooks, this temporal parietal fascia is also referred to as SMAS, superficial musculoseponiorotic structures of the head and face and they are used by plastic surgeons for various reconstructive procedures. So these are some of the points which I wanted to mention about the layers of the scalp. Thank you very much for watching. Dr. Sanjeev Sanyal signing out. Mr. Ken Dolcimer is a camera person. If you have any questions or comments, please put them in the comment section below. Have a nice day.