Anatomy of the Scalp

okay we're going to talk about scalp anatomy and answer the what questions what are the layers of the scalp and what arteries and nerve supply the scalp hello everyone my name is dr. morton and i'm the noted anatomist so the boundary of the scalp are through the anteriorly through the super orbital margins of the frontal bone here and then also laterally through the temporal fashion which attaches along the zygomatic arch and temporal bone and then posterior lis through the occipital bone along the superior nuchal line and external occipital protuberance and so the layers of the scalp to do that we're going to take this little coronal section from there we're going to blow it up and there we have a coronal section of the head and then they the orientation of this image is there's the layers of the scalp which we're gonna focus on in this tutorial but then there is the skull bones and there are the meninges and there is the brain now the layers of the scalp are as follows skin connective tissue ape and roses loose connective tissue and pericranium now you might ask myself ask me hey ask me self good grammar how do I remember these five layers Shing because the first letter all spells scalp and from superficial a deep those are all the layers let's do that we're gonna go through each one by one first skin the skin is the epidermis and the dermis has hair follicles sebaceous glands and the hair follicles are the big one that helps to keep it conserve heat and also gives aesthetic social purposes like this really pretty lady here that's my wife Selene now the connective tissue we offer this I basically adipose or loose adipose tissue fat that's deep to that and that's what houses a lot of the terminal ends of the cutaneous nerves and blood vessels then the ape and erotic layer the ape and neurosis this one we're gonna show in this bottom left picture in this lateral view here we see the frontalis muscle coming from the super orbital margin and the occipital is muscle coming from the occipital bone and these two muscles are attached by this dense connective tissue membrane called the Galea ape and erotica that goes widely to the sides that fuses with the temporal fascia which goes down to the zygomatic arch now this Gala ape in erotic is what I'm sewing a shirt first the skin connective tissue in a pan roses those three layers really function together which is often we call that the scalp of proper and so if you have a superficial skin laceration in the skin or the connective tissue layer the deeper neuroses will actually keep those two areas of cut skin pretty close together so it's actually pretty easy to suture but if we then do a deeper cut like you see that dotted line and the AAP neurosis then what happens is the frontalis and Xzibit Alice muscles contract and gape open that wound so laceration causes opening of the gala a pin errotica the frontalis and occipital muscles contract in opposite direction and the wound gapes open now the loose connective tissue layer that's deep to that or the areolar connective tissue this is where blood and pus and infection can spread all across the scalp now I show those emissary veins for the following reasons this fourth layer the scalp is the danger area because blood and pus can't go all the way through this area and an infection though it's not necessarily blood but pus and infection have a possible though unlikely route to go from this loose connective tissue layer through the emissary veins inside the cranial Vaught vault and cause an infection like meningitis the last layer is called the Perry cranium this is really the periosteum which is on the outside of the skull bones knitted so the perry cranium or periosteum is knitted to the bone and so there are the layers of the scalp except it looks like it says plaques but that's because scalp is just spelt that way okay there's the layers of the scalp now the cutaneous innervation of the scalp I'm gonna teach this through going through the back a front and lateral parts of the scalp so first let's look at the posterior scalp and so that cutaneous innervation is by the greater occipital nerve and the lesser occipital nerve and to see those two let's take a cross-section of the c2 spinal cord and spinal nerve watch the greater occipital nerve comes down and goes through the dorsal ramus and the lesser except blue nerve comes down and goes through the ventral ramus but they both go through that dorsal root that lesser occipital nerve is associated with the cervical plexus a greater occipital nerve those who do two sections you're going to see that really big nerve in the back right by the excessive occipital triangle now the anterior scalp we have the super orbital and super trochlear nerves and if we look at this picture here the v1 branch from the trigeminal nerve of the ophthalmic nerve gives rise to many branches the super orbital and super trochlear nerve being two of them and then the lateral scalp we have the a small zygomatic all temporal branch from v2 but also this larger auricular temporal nerve from v3 the mandibular branch of trigeminal nerve and there are all the cutaneous nerves of the scalp they're also the nerves that make it feel really good when you have one of those scalp massagers oh if you ever have one of those that that's a good way to finish a really long study break well the vascular supply to the scalp or the arteries or as follows they come branches from the external and internal carotid artery so let's take a look at external carotid first occipital posterior auricular and superficial temporal branches so the occipital arteries that come get their name because they're overlying the occipital bone the posterior auricular arteries get their names because they're behind the ear posterior behind auricular the ear and the superficial temporal artery gets its name because they're the superficial arteries overlying the temporal bone and these arteries particularly important in a can room at illogical condition called giant cell arteritis or temporal arteritis and in this superficial photograph you can see that superficial temporal artery it's the most common large vessel vasculitis and it's primarily affecting the cranial arteries in the aorta and the big one is a superficial temporal artery and that's the most direct vessel to take a biopsy to check to see if they'd really have vasculitis now the internal carotid artery branches so there's our internal carotid artery and so if we follow that up the neck it hits the base of the skull and then what happens is we need to get blood vessels to the above the eye to supply the front of the scalp but how do we do that well that internal carotid artery courses through the carotid canal through the cavernous sinus and then gives rise to ophthalmic branches that connect right there and then they give rise to the super orbital and super trochlear branches or arteries that supply to the front of the scalp now well notice is that there are rich and a stomata connections to all these scalp arteries and anastomosis that means a connection between adjacent structures and in this case arteries so there is an artery there's an artery artery artery and notice all those anastomotic connections and because of that there's a really rich blood supply to the scalp which makes it very easy for the head to give off a lot of heat which is why it's very important the wintertime to wear your toque good Canadian term there now scalp lacerations bleed profusely because you have so many nasty matic connections and also because cut vessels bleed from both ends if we cut there that if the vessel bleeds from this end and this end so if we take this and blow that up what happens is where usually when you cut a vessel the vessel only bleeds from the end being pumped from the heart but in the case of scalp arteries they bleed from both ends and then you have this really rich connective tissue network in the scalp that also helps keep the ends of these vessels open so people who have head injuries especially if they fall and hit their head they bleed not only because the bleeds from both ends but because these ends of the vessels are kept open so for scalp anatomy there's the scalp with all of its layers there's the nerves coming from c2 spinal nerve branches and from the trigeminal nerve v1 v2 and v3 and then all the arteries to the scalp which are branches from the internal and external carotid arteries and that my friends is scalp anatomy in a nutshell [Music] they will come she will buy Simon [Music]