A Simplified Approach to the Spaces of the Head and Neck

I hope to do for the next 40 four minutes or so, is to really demystify the spaces of the head and neck.

I'm gonna go through the various spaces of the head and neck. And again, a lot of what I do is anatomy. And anatomy is a common lexicon that we all have, whether we're a radiologist or a surgeon or a radiation oncologist. And I'm not really gonna be talking about the fancy stuff, the cology of the ology, but rather, I'm really gonna focus on the anatomy, because I really think if you understand the anatomy, then everything else just makes a lot more sense.

Masticator Space

The first space that we'll talk about is the masticator space. Now, pure and simply the masticator space contains the muscles of mastication. So if I had to contour the masticator space, I think you could see on the right side, this is where I'm contouring it just like that.

Now, the masticator space primarily contains the muscles of mastication. It contains the bones, which are primarily the mandible, and we'll see that a little bit later. And there's also a small little nerve that's located within the masticator space. So the three primary components are muscles, bones, and nerves.

So here on your left hand side, again, I'll make that little drawing right there. Here I'm contouring around the masticator space. I come around the muscles of mastication. I come around the condyle, the mandible. Then I'm gonna make this bump right here and then continue along the course. And that's the third division of the fifth cranial nerve.

So when we look at the muscles of mastication, we have the masseter muscle here, we have this little muscle right here, which is actually the temporalis muscle, which attaches to the medial aspect of the mandible. And then we have two muscles that are located here. Now, one is the lateral egid, one's the medial oid. And what I would submit to you, they're actually misnamed because the lateral turid is actually above the medial oid. So if I had to rename 'em, I would actually name it the superior and the inferior turid. But this lateral and medial sometimes makes things a little bit complicated.

So part of the question is, and the part of the approach is if you know that the largest component of the masticator space is muscle, then it becomes pretty easy to come up with a differential diagnosis. Because don't think head and neck pathology that involves the anatomy can arise anywhere within the body.

So if I told you that you have a mass involving the masticator space, we know that the largest component of the masticator space is muscle. Now, don't think head and neck, but think one of the peripheral organs of the body, to me, every organ outside the neck is a peripheral organ. So think the leg, right? Think the thigh. Lots of muscles there. If you had a pathology involved in the muscle, then all of a sudden if you were thinking the thigh, you'd think, well, maybe it's a rhabdo myoma, maybe it's a oma, maybe it's a mosis sarcoma, synovial cell sarcoma, lipos sarcoma, et cetera.

So the point being is that don't think head and neck specifically realize that any of the pathology that's involving other parts of the body can arise in the neck. So for instance, here's a pathology here involving the left masticator space. We know that the largest component of this is muscle. So this just happened to be a limy sarcoma involving the masticator space.

Another example here, and you know that the largest component of the masticator space is muscle. So what if I told you that this was a 12-year-old boy that had a rapidly enlarging mass in the head and neck? What would be the largest, what would be the most common diagnosis if this was in the masticator space? Lemme just yell it out. Rhabdomyosarcoma. Exactly. That's how you can use the anatomically based approach to evaluate the head and neck.

So we talked about the muscles. What's the other component? Well, another component is the bony anatomy of the masticator space. And again, don't think head and neck, this type of pathology that can occur anywhere within the body. And oftentimes people think of the leg, the thigh or the femur, et cetera. And we can make this diagnosis that's just an osteo involving the condyle of the mandible. And here on your right hand side, this is one of those crazy jaw lesions. And this starts with an A, an expansile cystic lesion. Um, anybody wanna take a guess at what this is? It starts with an a ameloblast stoma, exactly right. Again, we can come up with that just by knowing the anatomy of the masticator space.

And this is the third component of the masticator space. So the normal anatomy here is here's a lateral oid muscle, here's a temporalis muscle, and there's a little nerve right here. That's the third division of the fifth cranial nerve. Now on your left hand side, notice that we have a large mass right here. And look what it's doing to the OID muscle. It's actually displacing it laterally. So therefore this pathology is in direct apposition to the OID muscle, but it's displacing it laterally. So that means it's gotta be arising from that small little component. On this image. On the Corona image, we can see that pathology is extending superiorly and going through this foramen right here, which is frame oval. So this is pathology arising from the third primary component of the masticator space. And that is the third division of the fifth cranial nerve. So this happens to be a schwannoma. And this is another example of a schwan involved the masticator space growing superiorly.

So these are the three components of the masticator space. And so what we've done is if you understand that the anatomy of the masticator space is muscle, bone, and nerve, you can now come up with a pretty sophisticated differential diagnosis. The muscle. Think about Oma, mosis, sarcoma, rhabdo, myoma, rhabdomyosarcoma, synovial sarcoma, malignant fibrocystic, cytoma, all these things you've heard about. You just never thought of them being in the head and neck. Any place where you have bone, you can have pathology. And again, oftentimes we map it to another part of the body. So think metastasis, think infections, think primary bone tumors, a couple of those crazy jaw lesions. And remember the little nerve right there. So the three components of the nerve are, the three pathologies are schwannoma, neuro, neurofibroma. And then also we can have this pathology here too. And we'll talk more about this later. This is retrograde perineural spread of tumor growing up along the nerve.

So that's how you can take your approach to the masticator space. Again, it's anatomy, anatomy, anatomy.

Visceral Space

So let's go on to the next space. And that's the visceral space. Now, the great thing about the head and neck, or actually the worst thing about the head and neck is that we take the same piece of anatomy and give it different names. So for instance, if you came to this talk this year, I'll tell you one name and you're confused. You come to the same talk next year, I give you another name, you're completely confused, and then you have to come back a third time, right? It's a great gig. But what we ended up doing is for the visceral, for some of these fascial layers involved in the head and neck, this little fascial layer right here is part of the deep cervical fascia.

Now, most of us in the audience, I assume are radiologists. And part of the reason we went into radiology is because we were never able to dissect out the deep fascia of the head and neck. How many of you all remember the fascia of the head and neck are seeing it, right? Pretty much nobody, right? So anyway, so take everything you know about the fascia and forget it. Okay? That was easy, right? So I'll teach you what you need to know about the fascia.

So this fascial layer right here is referred to as the visceral fascia. Now this fascial layer, the way it received its name, was actually from the classic articles written in the 1930s. If you read the Stack Dx, or if you read some of Amherst, they've renamed this fascial layer as a faro mucosal fascia. So again, it's the same fascia. They've just called different names. I tend to use the term visceral fascia because that was the original name. Give it to it. So how do we remember what the visceral fascia is? Well, pure and simply, if you look in someone's mouth, that's the visceral space. So the space that's enclosed by the visceral fascia is the visceral space. So anytime an ENT surgeon takes it performs endoscopy or radiation, oncologist performs endoscopy, everything they see as they're putting down their endoscope is in the visceral space.

So another example here, here is the the visceral fascia. So again, that's just another illustration of the visceral fascia. And here's the most common pathology to involve the visceral space. So without even thinking about it, what do you think the most common pathology is gonna be to involve the visceral space? Take a wild guess. Yeah, squamous cell carcinomas. It's really one, two, and three. That's the most common tumor to involve the visceral space. And here we see it here and here we see it on the right hand side right here. So squamous cell carcinoma is number one.

Now what about this? What about this example here, another pathology right here. Now the thing about this case is that just illustrates the fact that 80% of what we see in head and neck, we can either see, can be palpated or seen at endoscopy. And this is just an example of adenocarcinoma involving the visceral space. There's no way you can make that diagnosis, but again, just illustrates a mass involving the visceral space.

So what about this pathology right here? Now, this is not necessarily pathology, but oftentimes we'll see this in kids. So if you see something like this in kids, you look at this and say, holy cow, is this a big tumor involving a child? But this is not the case. Anybody wanna take a guess at what this is? Adenoid? Exactly. Just enlarged adenoidal tissue in kids.

And what about this? Here's a submucosal mass involving the nasal pharynx. It tends to be high signal starts with a T, anybody torn, torn wall cysts. Exactly right? So we know a lot of head and neck. I think part of the head and neck is that we know all of this stuff. Part of it is just to reinforce what you know, and also to put it in a frame of context.

Retropharyngeal Space

So here's the real, the next space, and this one's a really hard space. What do you call the space that's located behind the pharynx? Really hard, right? Yeah. And to think I make a living outta doing this, right? So this is the retro pharyngeal space now for the aficionados in the audience. Um, here's the visceral fascia that's located right here. And there's another fascial layer right here, subdivide the space between the visceral fascia and the prevertebral fascia into two separate spaces. So does anybody remember the name of this fascia? It starts with an A. This is called the alar fascia.

Now the true retro pharyngeal space, the true retro pharyngeal space, it's located between the visceral fascia and the alar fascia. So this area right here that I'm pointing to is a true retro pharyngeal space. Now, the space that's located between the alar fascia and the prevertebral fascia is another space and it starts with a deed. Does anybody remember that space? That's called the danger space.

So back when Morton Myers' Day, he actually talked about the danger space, which is when, how I learned radiology. I never could figure it out. But if you can remember on Monday that the space that's located behind the retropharyngeal space and anterior to the prevertebral fascia, all of this area right here is a retropharyngeal space. I'm gonna be very, very happy. That's all you have to remember from a practical standpoint, and this is just an example of a patient that had trauma, and this is air within the retropharyngeal space. All of that is in the retropharyngeal space.

What about in this particular case? This was a patient that has a lots of adenoidal tissue involving as tonsils. But look at this right here, there is a carotid artery that's sometimes referred as wandering or moving into the retro pharyngeal space. So this is the retro pharyngeal carotid artery. And this is an example of a retro pharyngeal lymph node. Now we'll talk more about the lymph nodes a little bit later, but suffice it to say that there's two pairs of lymph nodes located within the retro pharyngeal space. And these are the retro pharyngeal lymph nodes. There's a medial and a lateral group, and this just happens to be a metastatic lymph node involving the retro pharyngeal lymph nodes. And in the later talk, when we talk about lymph nodes, we'll go over the importance of that.

This on the other hand, is not a true retropharyngeal space abscess. This is actually puss within a retropharyngeal lymph node. And the proper terminology of this is separative adenitis. This does not need to be trained, drained if the patient has a stable airway, rather that this is just puss within the retropharyngeal lymph node.

This on the other hand, is a true retropharyngeal space abscess. Notice the fluid within the retro pharyngeal space. The patient has already been intubated. And one thing, remember the retropharyngeal in the danger space is extend all the way down through the mediastinum, into the mediastinum. The danger space actually goes into the abdomen. So anytime that you are evaluating patients with this type of infection, make sure you include your imaging into the mediastinum because this patient had a severe mediastinitis.

Prevertebral Space

So the next space is probably the second easiest space. And you see this every single day. Now, you may not refer to it as this, but this is the prevertebral space. So the prevertebral space is enclosed by the prevertebral fascia, the other name for this fassal layer. Again, it's been renamed, it's sometimes referred to as the peri vertebral fascia or the peri vertebral space. Now you've seen this every single day. Anytime that you read a spine CT or a spine Mr. You have essentially been looking at the prevertebral space. We may may not call it the prevertebral space, but you know it already. So essentially this is really, really big review.

So here's an example of an osteomyelitis and a discitis extending anteriorly into the retropharyngeal space and then extending back into the epidural space. This, on the other hand, is another type of infection. Oftentimes seeing in India, there's relative preservation of the bone. Anybody want to take a guess what this is tuberculosis. And the other names is pot's disease. Exactly. Right now this is one of those head necky lesions, okay? This is involving the prevertebral space. This pathology typically avert arises at either end of the no cord, either at the bottom to the sacrum, or oftentimes here, right at the tip of the clus. So anybody want to take a guess at what this pathology is? Chordoma? Exactly right? A chordoma, typically they're high signal on T two and they densely enhance with contrast. And this is just sort of rare example of a neurofibroma. Again, I don't show this not to fool you, but I do want to emphasize the normal anatomy.

So on the left hand side is a schematic illustration of the prevertebral space. And on the right hand side, we can see this pathology essentially replacing the signal within the clovus and notice a normal signal on the clovus on the right hand side. So that's just happens to be a chordoma involving the prevertebral space.

One other example here, again, you know this already, you may not have put it into the prevertebral space, but here's a small little dissection involving the vertebral artery. Notice a normal lumen on the right side and the narrowed num lumen on the involved side with a little eccentric area of increased T one signal.

Parotid Space

So here's the easiest space, right? What do you call the space that contains the parotid gland, right? I mean, honestly it's that simple. But let's do a little review, right? So the masticator space is what contains the muscles of mastication. It contains the bone, it contains the third division of the fifth cranial nerve. The visceral space is anytime you look in someone's mouth, that is the visceral space. So the most common tumor to involve the visceral space is gonna be squamous cell carcinoma. The retro pharyngeal space is just behind the visceral space. So it's that space that's behind your pharynx, but anterior essentially to your spine. And then what is your spine? That is essentially the prevertebral space.

Now the parotid space, everyone knows what the parotid space is. You already know what the parotid space is. So I won't spend too much time going over the anatomy, but what I will say is that there's a specific nerve that's associated with the parotid space. Anybody remember the nerve? A facial. A facial nerve, exactly right, the facial nerve. And this is a patient that's undergone a superficial parotidectomy demonstrating the main trunk in the facial nerve and the various branches.

Now, you may not be able to see the facial nerve on your routine imaging, but you can have a pretty good approximation where the facial nerve is located by understanding one specific piece of anatomy. And that anatomy is right here. So there is a vein right here that's located behind the mandible. And anybody want to take a guess of what the name of that vein is behind the mandible? Take a wild guess. That's called the retro debitor vein. Head and neck. Is that easy? I wish it was harder. I wish it was like mammography or something. But head and neck is that simple.

The reason they call it the retro debitor vein is located right behind the mandible and the facial nerve is located just lateral to the retro debitor vein. And the facial nerve, as you can see, has a plane. It actually has a plane and it separates a protag gland into a superficial and a deep lobe. So one of the important things that we can say when we're evaluating patients with pathology involving the paric gland is whether it's in the superficial or the deep lobe.

So let's talk a little bit about some pathology that involves a paric gland. Now this patient has no history of malignancy, but rather they have multiple lesions that are benign lesions that are located in the tail of the parotid gland. Anybody want to take a guess what this could be? It starts with a W Yeah, Hans tumors, the reason they call 'em Hans tumors, so the other name for Hans tumors is cyst adenoma lymphoma. Now what does that mean in English? That's the Latin derivation. What that means is that these tumors are felt to arise from intra parotid lymph nodes.

Now the parotid lymph nodes are located in both parotid glands. They're typically in the tragal area below the capsule of the parotid gland around the facial nerve or in the tail of the parotid gland. So in general, this is what's referred to as the earring lesion. So if you've read in the textbooks about Han's tumors tend to be multiple and bilateral, that's the reason they tend to be multiple and bilateral because the lymph nodes tend to be multiple and they tend to be bilateral in the parotid gland.

Now, this is a pathology we don't see as much anymore. I think those of you in the genre of the nineties like myself. And in the eighties we saw this routinely. And this was a patient with HIV and anybody want to take a guess of what this is then? Lympho epithelial cyst, right? Radiologists, we don't get older, we get more experienced. I dunno if there are any more experienced radiologists in the audience, but I'm one of those. But these are the lympho epithelial cysts that are typically associated with HIV.

And this is just an example of a patient underwent a superficial ectomy and a total ectomy. And the key thing is here is if you undergo a total ectomy, the surgeon has to dissect all the way through the plane of the facial nerve. So this is an example of a small pleomorphic adenoma involving the superficial lobe. And this is an example of a pleomorphic adenoma involving the deep lobe of the parotid gland and extending into this space, which is the para pharyngeal space, a space right next to the pharynx.

And this was an example of a patient has a tumor that's involving the parotid gland. Now remember, if you have a tumor involving the parid gland, the surgeons can already determine whether it's malignant or benign. Why? Because whether or not the facial nerve is intact, if the facial nerve is out, if it is not working, then the surgeon knows that the facial nerve is involved. But what they don't know is how proximal the tumor extends. So our job as the radiologist is to determine whether or not there's involvement of the facial nerve.

So if I draw my line down the middle and compare one side to the other side, can I convince you there's enhancement here versus no enhancement on the opposite side? So this is actually retrograde peroneal spread along the facial nerve. Very important information for the surgeon because then he's gonna, or she, I've got a daughter and a wife that's a physician, right? So I always say he, he or she will have to determine whether or not there's, they will have to go in and actually drill out that facial nerve. So they could treat this with non-surgical organ preservation therapy or if they wish they could actually go in and drill out the facial nerve. But this type of decision is really based on what we say on the preoperative imaging.

Parapharyngeal Space

Well, this space is pretty easy as well too. What do you call the space that's located next to the pharynx and pure and simply, that's the para pharyngeal space. Now if those of you that are Latin majors or are studied in the classics, you will realize that para actually means above and juxta means next to. But for some reason we have adopted the name as the para pharyngeal space. So the para pharyngeal space is really that space that's next to the pharynx.

There really isn't a lot of anatomy in the para pharyngeal space. There's small little lymph nodes that occasionally come into play, but it's rare. But most of it is just fat and some fibro fatty tissue. The most common tumor to involve the para pharyngeal space is deep extension of this tumor. And I'm sure we'll hear more about this later today, but this is squamous cell carcinoma extending into the para pharyngeal space.

The para pharyngeal space is tr typically visualized as this triangular region of fat that's just deep to the tonsil. And notice how it's just lateral here to the masticator space. So that's a normal appearance of the para pharyngeal space. So in the case on your left notice, we have this tumor involving the tonsil and it's growing deeply to involve the par pharyngeal space. So that's the most common tumor to involve the par pharyngeal space.

Now, the most common tumor to arise in the par pharyngeal space is a minor salivary gland tumor. And that is a pleomorphic adenoma. Now notice how this is in the para pharyngeal space. Look what it's doing. It's displacing the oid muscles laterally. It's displacing the tonsil immediately. Now notice what it's doing to the carotid artery and the jugular vein. The carotid artery is being displaced posteriorly. So therefore this lesion has to be in the para pharyngeal space. And I wanna emphasize again, and especially when we talk about the next couple spaces, is this mass effect on the carotid artery identification of the carotid artery is key in order to determine what spaces these lesions are in.

So again, just to emphasize, the most common tumor to involve the para pharyngeal spaces, deep extension of squamous cell carcinoma, the most common tumor to arise in the par pharyngeal space is a pleomorphic adenoma. And this is just another example of a lesion involving the par pharyngeal space. This has a fluid, fluid level. Notice how the carotid artery is being displaced posteriorly, which places this in the par pharyngeal space. So this just happens to be a lymphatic malformation.

Carotid Space

Now the next one's pretty simple too. What do you call the space that contains the carotid artery? Well, pure and simply, it's a carotid space. But again, this is where the confusion comes in because the carotid space actually has three names to it. So I as a radiologist call it the carotid space because I think it's easy for us to remember it because it contains the carotid artery. The other terminology that used is the carotid sheath. And this gets back to the anatomy and the carotid space, having a sheath that surrounds it. So some will call it the carotid sheath.

Now the surgeons use the nomenclature post styloid para pharyngeal space. So if you're interacting with ENT surgeons, the way they tend to view this region back here is that they can see this styloid process. Now, what we refer to as the paranal space, the surgeons will refer to this as the pre styloid para pharyngeal space. What now, what we're referring to as the carotid space, the surgeons will refer to this as the post styloid para pharyngeal space. So again, like I mentioned earlier, the same anatomy, we just give it different names and I think there's relatively good consensus in the radiology world that we'll just refer to this as the carotid space.

Now, what are the components of the carotid space? Because if you can understand the anatomy, everything else makes sense. So you have the carotid artery, that's big red. We have big blue black here, which is what the jugular vein. We have cranial nerves nine through 11. And then we have lymph nodes. So those are the four primary components. And again, what I just mentioned, the the artery, the vein, lymph nodes and nerves can be seen anywhere else in the body. So again, if you just focus on head and neck and we all get a little bit nervous about the head and neck, it can be challenging. You tend to forget stuff, but just think of all this anatomy and other parts of the body and then you can come up with a pretty nice differential diagnosis.

So for instance, what's the diagnosis here? Uh, dilatation. Focal dilatation of the carotid artery. It's a big one aneurysm, right? This patient on the right hand side had an indwelling catheter. Here's the carotid artery, just lateral to it. We should see the jugular vein, which we don't see. So this is jugular vein thrombosis. So there's your first two pathology, right? Aneurysm in jugular vein thrombosis. If the patient had trauma, we can see narrowing of the lumen of the carotid artery surrounded by the eccentric area of increased T one signal. The answer is what? Dissection, right? Another one.

Now what about in these two cases? And these are somewhat head and necky, but the key thing here is once you start evaluating these lesions, find the carotid artery. So on the patient's right hand side, there's a carotid artery, and here's the carotid artery. Notice how it's being displaced superiorly, right? Notice how this carotid artery is displaced superiorly. What's the difference between the internal architecture between this lesion and this lesion? What do we see here? These black dots that we don't see on the left hand side. Those are what? Those are flow voids. Exactly right. So the diagnosis here is what? It's a gloma tumor. And the diagnosis here is probably gonna be what? Schwannoma, right?

So the key thing here is how do we know they're in the carotid space? Look for the displacement of the carotid artery. So let's talk about this a little bit more. Another example of a carotid space mass non-contrast enhanced T one weighted image carotid arteries displaced anteriorly. Notice how the internal architecture is very bland. That's the schwannoma on the T two weighted images. We can see the little bit of increased signal, but the key thing here is that there are no flow voids.

This on the other hand, contrast enhanced ct contrast enhanced T one weighted image on the right hand side. Notice how the carotid artery is displaced anteriorly. And we can see the multiple flow voids within this lesion. And that means it's a gloma tumor. Sometimes this has been referred to, and I don't like the terminology, but it's buried in our lexicon as the salt and pepper appearance.

Now there are different types of gloma tumors. If one of the gloss tumors arises from the carotid um body and separates the internal and external carotid artery, this is referred to as a carotid body tumor. And this is the same lesion after embolization. Notice the separation of the external and the internal carotid artery. If on the other hand the same pathology, the gloss tumor arises from this ganglion of the vagus nerve, which is referred to as the no dose ganglion, then this actually pushes and compresses the internal and the external carotid artery. So this is what's referred to as a gloma vali tumor. It's the same pathology, it ha just has a different origin. So instead of rising from the carotid body, it's arising from the no dose ganglion. And this is the same lesion after embolization.

And if you have that same pathology, but it arises from the superior cervical ganglion in the jugular frame, then this is what's referred to as a gloss jui. So it's the exact same pathology, it's where the origin is. And if you took it to the nth degree, what would you call the same lesion? If it rises in the middle ear cavity, that would be a what? A gloss tympanum. Exactly. Exactly right. And I'm sure you'll hear more about that later.

And this is one of those weird pathologies. This is really a diagnosis of exclusion. This was an enhancing lesion that's encasing the carotid artery. The patient has no history of malignancy, no history of squamous cell carcinoma. The patient is painful to touch and the pain is relieved by giving aspirin. Does anybody know what this is called? It starts with a c carotid inia. Exactly right. Have you heard of carotid inia? So it this will pop up on you and I've seen it a couple times. It's basically this diffuse soft tissue mass that encase the carotid artery, painful to touch. And it really is a diagnosis of exclusion because you have to exclude everything else. Certainly this could be other pathology, but in the absence of everything else, and you have to consider the diagnosis of carotid Nia.

Sublingual Space

Well, the last two spaces we'll discuss are again, are very, very simple spaces. So again, you know, we switched names. So what's Latin for? Tongue? Anybody lingua? Exactly. And what's Greek for tongue? Anybody? You guys never, nobody took the classics, right? You're all anatomy biochemistry majors, right? It's gloss, right? And the reason why I mention that is because that again gets to the confusion in the spaces of the head and neck.

Because the space that we're referring to right now is referred to as the sublingual space. It's below the tongue and we will use the Latin root. But on the other hand, once we start talking about the muscles, and I'm specifically gonna talk about this muscle that runs from the hyoid bone to the tongue, that is the hi gloss muscle. So we switch our roots instead of this being the ual muscle, it's the hy gloss muscle. So again, we tend to switch our roots.

So this sublingual space is all of that space that's located below the tongue. So again, if I had to look at this, this is the normal anatomy. So this is the mandible. This muscle right here is the myelo hyoid muscle. And the muscle goes all the way down to the hyoid bone, which is located here. So anything that's below the tongue but is located within the mylohyoid muscle and medial to the mandible. All of this is in the sublingual space. And if you look at the way I, if you take the same drugs I do, if you will, it almost looks like a teacup to me. So anything that's within the teacup is within the sublingual space.

So when I look at this teacup, I think about the rim of the teacup being mandible, the wall of the teacup being this mylohyoid muscle and the base of the teacup being within the hyoid bone. So anything within the teacup is within the sublingual space. Now what are the components of the sublingual space? Well, you've got arteries, you've got nerves, and you've got this little gland, which is the sublingual gland. But you also have a duct that traverses the sublingual space. And that is Han's duct. That's the duct of the submandibular gland. Remember the submandibular gland has a little duct, it crosses in the sublingual space and the fluid comes right out at the frenulum within the sublingual space. So that's the primary anatomy. You've got the muscle, the arteries, the duct, and the gland.

Now certainly the most common tumor to involve the sublingual space is going to be squamous cell carcinoma. As we see here. Again, number one, two, and three is squamous cell carcinoma. Squamous cell carcinoma is one. The second most common tumor is gonna be a minor salivary gland lesion. But by far and away, if you see an aggressive lesion in the sublingual space, it's gonna be squamous cell carcinoma.

This on the other hand, patient has a fever. We see a fluid collection. When you look at the tooth, it looks pretty bad. And maybe there's a little bit of osteomyelitis. So what's the diagnosis here? Anybody? Yeah, just a sublingual space abscess. So always remember when you have a sublingual space abscess, reconstruct your CT scans into bone algorithms and start looking for the rotten bone, if you will. And this was just due to a chronic odontogenic process. This could have been actin mycosis, right? Actin mycosis is the classic infection that involves the bone. But the suffice it to say the main thing here is just remember these abscesses that involve the sublingual space.

Now these two lesions are developmental lesions that arise in the sublingual space. This one is anterior and midline. Now, not posterior midline, we'll talk about this later, but anterior midline. So anybody want to take away this is starts with an e epidermoid. And then what about this lesion here? That's paraline and think frog granula. Exactly right. So that's the granula. So posterior midline is thyroglossal duct cyst. Anterior midline is epidermoid, and paraline is the granula.

Now the granula is a congenital obstruction of the sublingual gland. And if the granula is located above the mylohyoid muscle, or should say medial to the mylohyoid muscle and above the hyoid bone. So it's in the sublingual space. And this is what's referred to as a simple granula. And the reason why it's important is because a surgeon can go in to an intraoral approach and marsupial and resect the granula. So it's a very, if you will, straightforward approach.

Submandibular Space

Now the last space is referred to, again, very simply, what do you call the space that's below the mandible? Well, it's just the submandibular space. Again, very, very simple. Oh, by the way, what space am I contouring right here? That goes up to here. Ator space. Exactly right. Good. So here's our mylohyoid muscle. Here's our high gloss muscle. Everything above the mylohyoid muscle or between them is within the sublingual space. Anything that's below the mandible is located in the submandibular space.

Now there's again, not a lot of pathology in the submandibular space. We'll spend a fair amount of time talking about the lymph nodes. These are the level one lymph nodes or the submandibular lymph nodes. But in general, there's just not a lot of pathology in the submandibular space. These are the level one lymph nodes. Again, we'll spend a lot more time going over those. So we'll save that for a little bit later.

This on the other hand is some pathology involving the submandibular space. So here we have an abnormality involving the left submandibular space. We can see this little tubular structure that's dilated and we see this little guy right here. So what is this? It's just a small little s lith with dilatation of hans duct. And this is given you what we refer to as an obstructive S adenitis involving the submandibular gland. So don't confuse this for the lymph node. That's one of those common pitfalls. You look at this and you say, wow, look at that. It could be a metastatic lymph node. But the key thing here is to look at where you'd expect to see the hilum and see that dilatation of the duct.

Now another example here, this is again in large subandi submandibular gland. Notice the normal submandibular gland on the right hand side. So what's your thought process? You see something like this and you say there's dilatation of the submandibular gland. Now remember the duct of the submandibular gland courses through the floor of the mouth. So now you have to pay very, very close attention to the floor of the mouth. And you have to understand what that course is.

So if I can convince you on the normal side, there's normal fat within the sublingual space, and these are the enhancing vessels that we typically see when we give contrast. Now, you know, the duct has to course in the sublingual space. Now with a leap of faith, can I convince you that there's a subtle lesion right here involving the sublingual space? Everybody see that? That's actually a very subtle squamous cell carcinoma. Now you say, wow, that's pretty subtle. But what increases my diagnostic conference confidence that this is real? Because this was path proven squamous cell carcinoma. What increases it is the fact that this gland is you have an obstructive sil adenitis. If that wasn't there, you know, you wouldn't be as confidence. But the fact is that gland clearly is obstructed and there has to be some causative agent that is leading to that obstruction that, so that's a little subtle squamous cell carcinoma.

By the way, this muscle that runs through the genial tubercle back to the tongue base. Anybody know what that muscle is? Genial, tubercle to the tongue base genial gloss. Exactly right. That's the roots, right? It's not genial lingua, it's genial gloss. So that principle that I mentioned earlier about taking the same piece of anatomy and giving it different names, that's where their confusion comes in. So all of these muscles here again, revert back to the Greek root as opposed to the sublingual space, which is the Latin root.

And this is one more example of a granula. Now this granula, again paraline, but look what it's doing. It's extending into the submandibular space. So we have a ula extending into the submandibular space. Again, we take the same piece of anatomy, we give a different names. We have three names for this type of granula. Remember if the granula is only in the sublingual space, and that was called a simple granula. But if the granula extends into the submandibular space, it has three names to it. I think we've probably all heard of it. If it's not simple, it's what? It's complex. So that's one name to it. If the granula extends below the mylohyoid muscle, it dives through the mylohyoid muscle. So that's why it's called a diving granula. Or it can be referred to as a plunging granula.

So the point is, is that this type of granula that extends through the mylohyoid muscle into the submandibular space is referred to as a diving, a plunging or a complex granula. And again, folks in the audience, I didn't give it the names. I'm just trying to explain it to you and try to eliminate some of the confusion. But why is that important from a clinical standpoint? Remember the simple ULAs that were located within the sublingual space could just be marsupial through an intraoral approach. But on the other hand, if we, the radiologists say that this ULA is extending into the subandi space, then the surgeons have to take a cervical approach as well in order to resect it. So that one little piece of anatomy saying that's extending into the subandi space changes the surgical approach to these lesions.

Summary

So in summary, what I've tried to do over the last 40 five minutes or so, is go over the spaces of the head and neck and give you a simplified approach to these. We talked about all of these areas, and again, what I've tried to do is just emphasize the anatomy. It's the anatomy of the anatomy of the anatomy. If you can understand the anatomy, then I think all the spaces will make sense. So thank you very much for your attention.