hello everybody and welcome back to another Anatomy tutorial today we're going to be looking at the Deep neck spaces as well as the Deep cervical fascia that separates and encases the various different neck spaces now a lot of you have been asking me to cover this topic and I know why because when we start learning head and neck Anatomy looking at axial slices of the neck can be really intimidating there's so much Anatomy going through such a small space and hopefully by the end of this talk you'll become comfortable with compartmentalizing the neck into the different spaces then it becomes much easier to identify the anatomy as well as knowing what is normal and what is abnormal now the first thing we need to do is separate the neck into a suprahyoid and an infra hyoid neck so if you look at this sagittal CT scan here if we draw a line through the hyoid bone anything above that line is known as a suprahyoid neck anything below that line is the infra hyoid neck now we're going to start by looking at about this level of the infohyoid neck on a still image I'm not going to scroll through it and I'm going to show you the different components of the deep cervical fascia so let's have a look at this axial T1 weighted slice of the neck and just orientate ourselves first so this is the anterior side of the patient outrachea lying anteriorly with the strap muscles and the sternocleidomastoid muscles out anterior and then we can see our vertebral column and our trap muscles back here that is the posterior portion of the patient now if we're going to be identifying the Deep cervical fascia it goes without saying that there's probably a superficial cervical fascia so our superficial fascia runs along this red line now The Superficial fascia of the neck is the same as a superficial fascia that we find throughout the body lying just underneath that subcutaneous tissue so we can see this small layer of fat running like this and if we look closely we can see a thin muscle running on both sides there and that's our platysma muscle if I was able to grow a beard I would contract my platysma muscle to make the skin taut on my neck and that platysma runs external to our superficial cervical fascia now our deep cervical fascia is split into three different fascial planes as Radiologists we call them our superficial middle and deep planes anatomists or if you're looking in a textbook name it differently and I'm going to show you as we go along what they call it but essentially they're the same fascial planes so the first fascial plane is the one outlined in blue and that's our superficial layer of our deep cervical fascia now you may see this in a textbook or anatomist calling this the investing layer of the deep cervical fascia and they're just synonyms but as Radiologists we call it a superficial layer of our deep cervical fascia now that layer runs anteriorly here to our strap muscles then it encases our sternocleidomastoid muscle heads out posteriorly encasing altropezius muscle and then wraps all the way around the posterior here and as we look later and we scroll up into the Super hyoid neck that then creates other different neck spaces but in the infrahyoid neck space it's encasing our sternocleidomastoid and trapezius muscle as well as providing a fascial pain for that anterior border of our strap muscles the next plane is our middle layer of our deep cervical fascia now in textbooks you may see this called the pre-tracheal fascia it's the same thing but as Radiologists a middle layer of our deep cervical fascia now that encases our trachea our esophagus our thyroid gland you can see the thyroid Isthmus here obviously our parathyroids would be involved in there too and that space hits all the way up to the hyoid bone where it then becomes a different name but the same space essentially being encased by our middle layer of our deep cervical fascia you can see also there it provides a fascial border on the posterior portion of our strap muscles now they're called strap muscles because they basically look like straps like bolt straps or bag straps that head from our hyoid bone to various portions of the neck then our last fascial plane here is our deep layer of our deep cervical fascia in textbooks you might hear this called our pre-vertebral fascia but as Radiologists we call this our deep layer of our deep cervical fascia you can see it in cases the para vertebral muscles the vertebral column itself and spinal cord all of this is our deep layer of our deep cervical fascia see anteriorly that it butts closely to that middle layer of the deep cervical fascia now if you look at these three planes you can see they surround this space which is known as the Carotid space now the Carotid space doesn't have its own separate deep cervical fascal layer and in fact the three layers The Superficial the middle and the Deep layers all contribute to that carotid space so now these spaces here we've got anteriorly our middle layer of our deep cervical fascia forms What's called the visceral space now that lies below the hyoid bone infra hyoid it's called our visceral space and that is basically surrounding organs that head into the viscera our trachea goes to a visceral organ it goes to our lungs our esophagus goes to our stomach and this fascia as it heads down into the mediastinum will then become continuous with our pericardium itself that's called our visceral space that's the first space that we've actually identified here in the infra hybrid neck posteriorly this is called our peri-vertebral space here so our deep layer of our deep cervical fascia surrounds our peri-vertebral space and then these three fascial planes coming together surrounding this space this is known as the Carotid space each of these spaces head up into the Super hyoid neck and remain those spaces as we head further up we'll see in the superheroid neck that other spaces begin to develop Okay so we've identified our visceral space our carotid space and our peri-vertebral space now you can see that I've joined the two carotid spaces with this orange line now it's debatable whether this Orange Line actually extends all the way to the Carotid space but what this line represents is called our Ayla fascia so our visceral space and our peri-vertebral space the middle layer and the Deep layer of our deep cervical fascia actually abut one another and there's this thin membrane that runs separates the two of them called our Ayla fascia now as you can imagine there's no space between those they're completely against each other and if we were looking on a scan we wouldn't be able to identify these different fascists from one another but if there was fluid to track between those fascial planes or a mass to go down between those fascial planes those potential spaces then become actual spaces so there are two potential spaces that can form here we have the space between our middle layer of our deep cervical fascia and the Ayla fascia so anterior to that adolar fascia and posterior to our visceral space if that was to open up that's what's known as our retropharyngeal space this is also the same in the suprahyoid neck which we'll look at later but our retropharyngeal space is a potential space that if fluid or infection were to track in that would separate the middle layer of the deep cervical fascia and our Ayla fascia from one another and that space heads all the way down until our middle layer and a-lar fascia fuse at about the level of T1 then posteriorly to our Ayla fascia and anteriorly to this deep layer of our deep cervical fascia is another potential space which is known as the danger space and the danger space heads all the way down into the thorax and the fusion happens at about the level of the diaphragm so all the way down at the level of the diaphragm that dangerous space can track and we can have infections tracking all the way down or masses or fluid tracking all the way down right to the level of the diaphragm so if you see this space being opened up on a neck scan we need to then investigate further into the chest to see how far the extension of that mass or fluid or infection goes so to recap we've got our visceral space surrounded by our middle layer of the deep cervical fascia we've got our peri-vertebral space surrounded by our deep layer of the deep cervical fascia then we have our car rotted space which has fascia coming from our superficial middle and deep layers and lastly we have these two potential spaces our retropharyngeal space that can head all the way down to the level of T1 and our danger space line between our Ayla fascia and our deep layer of our deep cervical fascia that can head all the way down to the level of the posterior diaphragm so let's have a look at a scan where we can actually scroll through and see how these spaces change as we head inferiorly or superiorly in the scan so here we have an axial T1 weighted scan of the neck we can see we're at the level of the mandible and as we scroll down inferiorly we can see our hyoid bone come into view so we know anything inferior to this is our infra hybrid neck exactly what we were looking at before so let me try and find a plane which is very similar to what we were looking at so if I stop here we can see our strap muscles our thyroidismus you can see that sternocleidomastoid our carotid space our peri-vertebral space coming here as well and then if we head superiorly up towards the hyoid bone we can see how those spaces change so let's get to the level of the hyoid bone there we are here our peri-vertebral space remains our peri-vertebral space our superficial layer of our deep cervical fascia is still surrounding the sternocleidomastoid and trapezius muscle here and then what was known as our visceral space now becomes a pharyngeal mucosal space it's still continuous that fascia is still continuous up into the superhighod neck but now we call it the Fringe only causal space our karate space remains our carotid space as well and as I go into another scan later I'm going to color code these and it's going to become much clearer to see these spaces as we head up through the neck but I first want to show you them without the color coding so you can try and visualize for yourself where these spaces form so let's go Superior to that hyoid bone and I want you to look at our superficial layer of our deep cervical fascia covering our sternocleidomastoid and our trapezius muscle as I head superiorly you will see sternocleidomastoid heads posteriorly and we can see these muscle groups coming in to the picture I'm going to stop here we can see that we have our muscles of mastication coming in surrounding our ramus and our body of our mandible here now these muscles are grouped into the next next space that we're going to name and that's our masticator space and you can see how superficial domesticated space was just like our sternocline and mastoid muscle and so this masticated space is still surrounded by our superficial layer of the deep cervical fascia we have our medial and lateral pterygoids as well as our masseter and our temporalis muscles making up that space and we have our mandible coming in there so if a mass was coming from this space we've got muscle we've got bone it's likely to be a sarcoma another space that's developed here is this space here you can see me outlining without my mouse this is our parotid gland and our parotid gland makes up the parotid space we can see we have a superficial lateral limb of our parotid gland as well as a deep medial limb here of the project gland that's good to notice here we can see our parotid gland lies slightly lateral to our carotid space and now we know this space here which was our visceral space has become Alpha ringzone mucosal space our peri-vertebral space that we identified earlier is still the Peri vertical space and remains a very virtual space all the way up to the base of the skull so those are all our next spaces we've done our visceral space which was covered by our middle layer of the deep cervical fascia we have our peri-vertebral space covered by the Deep layer of our deep cervical fascia and we have our carotid space heading all the way up that has contributions from The Superficial middle and deep cervical fascial planes and now that we've headed into the Supra hyoid neck we have our masticator space as well as our parotid space we can see that lies lateral to our karate space and then in between as I scroll up you'll see that there's this fatty space here between our masticator space our pharyngeal mucosal space our parotid space and our curated space and this is perhaps the most important space in the head and neck now whenever you're looking at a scan the first thing that you should identify is this space we can see it's bright on T1 weighted it's the same as our subcutaneous fat here this is a fat fold space this is what's known as our parapharyngeal space a really important space to become aware of because there's not much pathology that actually arises from the parapharyngeal space but if anything was to arise from domesticated space it would displace that parapharyngeal space posteriorly from our pharyngeal mucosal space if we displace it laterally if we have a mass in our parotic gland it would displace that fat anterior immediately and the same with our curated space would then displace that fat anteriorly and is that displacement of the fat which allows us to recognize where a mass or an infection is coming from and we can use this as a really good indicator for where the mass is coming from rather than trying to guess because this Anatomy is so closely linked to one another sometimes when we have a big Mass it's quite difficult to see where that mass is coming from if we have a look at this on a CT scan I want to show you what the parapharyngeal space looks like on a CT scan because often we'll be picking these lesions up incidentally we'll be doing a CT scan or a CT neck for perhaps trauma and then we see a mass in the neck and we need to decide where is this Mass coming from so let's scroll up to that same layer again we get it here we can see how masticated space here we can see our parotid space you can see our styloid bone here which will become important later I'll show you why and we can see our pharyngeon mucosal space and laterally here it's now dark on a CT scan we can see that fat is hypodense on a CT scan we've got that same look here in our para pharyngeal space here and we when we're scrolling through a scan it's good to look at that see if those fat spaces are normal fats are really good clue for us to see if Mass if a mass is Shifting so as I said we're going to look at a color-coded version of these diagrams I'm going to start down in the infrahyoid neck where we were head my way up and show you the different spaces and sometimes much easier now you can compare the right hand side to the left hand side and try and identify those spaces for yourself you can see how strap muscles lying anteriorly to our visceral space here our sternocleidomastoid and trap muscles posteriorly and then we have our Peri vertebral space heading all the way around here and that's surrounded by our deep layer of our deep cervical fascia and you can see how our superficial middle and deep layers then all in case this space which is our carotid space so let's follow that visceral space upwards we're going to head all the way until we see the hyoid bone see the hyoid bone there and we can see that that visceral space then becomes our pharyngomycosal space you can see Alpha mucosal space covering the lining of our pharynx and our oral pharynx and that whole mucosal lining there you can see it lies medial to our parapharyngeal space which we'll see highlighted here in light blue our parapharyngeal space is then itself medial to our masticator space with our muscles of mastication our pterygoides as well as our masseter and temporalis muscle the parapharyngeal space lies slightly anterior medial to this deep limb or this medial limb of the parotid gland we can see how superficial limb there of the protocol and going out to the periphery and our carotid space lying posterior to that parapharyngeal space as we head upwards we can see how this peri-vertebral space Remains the Same all the way up and it's sometimes good if we look at this parapharyngeal space to think of it as a cone or a upside down pyramid as we get closer to the base of the skull it gets wider and then as we head down it becomes a point basically all the way going down to the posterior horn of this hyoid bone here you can see it coming up here getting bigger so as always I've linked these images in a radiopedia playlist below and I really encourage you here to spend the time scrolling through these images and learning the different spaces and then go to a normal MRI scan scroll through and try and identify those spaces for yourself now I mentioned earlier as well that the parapharyngeal space is a really important indicator for where a mass is arising from and I just want to show you an example of that before we head off and finish the talk so here I've got another axial T1 weighted scan now T1 is really good when looking in the neck because we've got this bright fat we can see where the fat is being shifted now the obvious abnormality is sitting right here anterior to our vertebral column medial to our mandible here and we need to now decide where is this Mass coming from this could be coming from alphainger mucosal space you can very easily see that it could be coming from our masticator space it could be coming also from the parotid or the Carotid spaces and this is where we need to use our parapharyngeal fatty or parapharyngeal space we can see it on the right hand side of the patient here we see where has that fact been displaced to on the left-hand side of the patient we can see it's been displaced anteriorly and medially here so it's very unlikely to be the masticator space because that would displace this fat posteriorly the same with our pharyngeal mucosal space that would displace the fat laterally so it's likely to be coming from our parotid or our curated spaces now here's another good trick to identify whether it's coming from the parotid or the Carotid is to look at our mandible and then try and identify our styloid bone we can see our styloid bone here and our thyroid bone here and this is a Stylo mandibular tunnel here or stalomandibular Canal we can see it's widened on the left hand side of the patient because our parotid comes between the mandible and the styloid and our carotid space lies medial to that styloid so if we see expansion of that stylum mandibular space there or solum and nebula tunnel we can quite confidently say that this mass is actually coming from that deep lobe of our parotid gland extending into the parapharyngeal space displacing that fat anterior immediately so I know it's a lot to cover but the best way to go about this is to identify the cervical facial layers our superficial middle and deep layers see which spaces those are creating and then follow that space up through the neck all the way up from the infra hyoid region into the suprahyoid region and if you take one thing from this talk look at the parapharyngeal fat see if that is being displaced if it is then go about looking for a mass and trying to identify where that mask comes from so thank you so much for joining me I hope that has helped you in some way let me know as always which topics you would like me to cover in the comments section below and until the next video I'll see you all goodbye