Estimated reading time: 9 minutes
In today’s class, we are going to be discussing CVJ craniovertebral junction, which I believe is a difficult topic for most of us until we remember the line then it is something that you do not really have to memorize, keep it handy and then whenever you are reporting a case, just quickly have a little bit of lag, I do not know, but it should settle soon. So let us begin, we will briefly discuss the anatomy in the beginning and then I will jump off to the craniometry and then we will look at the cases, so that is how the class is going to run. So this is the part that we have to discuss, so I have the CT and the MRI images here.
So, let us start, you guys have to tell me the answers, okay, so a few of the things are pretty basic stuff only. So what is this point here, anybody can tell me what is point A, what is this point where the frontal bone meets here, yeah big frontal beak, but what do we call this? Yeah, this is the nasion, right, where the frontal beak meets the ethmoidal bone, so this is the nasion, correct. What is point B here? What is this anterior wall of the cella, what do we call that, the anterior wall? It’s the tuberculum cella, good, what is the posterior wall? Obviously, that is the dorsum cella, so point B here is the tuberculum cella.
What is point C? So this is the basioxyput or the clivus, so what is the most posterior part of the clivus called as? That is the basion, so that is something which is very important, so this is the basion point. So what is point D here? What is point D? That is the basion opisthion, right, so you must have heard basion opisthion line, so D is opisthion. Where is point E? What is E? E is the hard palate, all of these points are very important because all the lines that we are going to learn are going to run from these points, so it’s very important that you recognize what all of these points because these are the lines that I’m going to teach you, okay.
So E is hard palate, what is F here? Yes, F is atlas, what atlas? interior arch of the atlas, right, so F is the interior arch of atlas and what would be G? G is the posterior arch of the atlas, fine. What is H? Pretty easy stuff, so that’s C2, what part of C2? That is the dens, right, dens or odontoid of the C2 and I is the body, body of C2, yeah, so this is something which all of us understand. Coronal, same, let’s see coronal, what is point J, the topmost point? This is the hypoglossal canal, so what is this beak which is forming the hypoglossal canal, the eagle appearance that we have learned? It is the jugular tubercle, so J, J for jugular tubercle, it’s the jugular tubercle which is going to form the beak, the eagle’s beak in which the hypoglossal nerve is going to run.
What is K here? What do you think is the point K? So that is the occiput, right, so this is what is the occipital bone, so this is the occipital condyle, so point K here is the occiput or the occipital condyle. What is point L? L for L only, what are these? These are the lateral masses, yeah, we saw the interior arch and posterior arch of the atlas, so these are the lateral masses of the atlas, so L for lateral mass, okay and finally we have H which is odontoid or the dense and I is the body of C2, so this is what is the normal anatomy, all of you following from first year till final year, everybody got this, okay, so this is what you have to understand.
One quick refresher, one more time very quickly, nasion, anteriorly, tuberculum, hard palate, these are the anterior points, keep that in mind, basion, opisthion, atlas, anterior, posterior, dense, coronal, jugular tubercle forming the occiput, lateral masses and here we have C2, so basically occiput, atlas and C2, these are the two joints and you always have to see the symmetry in terms of the distance on both the sides and in terms of the joint space on both of the sides, no need to memorize here, this is all about symmetry, okay, so this is how we have to approach the CT.
MRI, same bony points, very quickly, so see the same bony points, so we don’t have to run through the points again, this is the hard palate point, this is the tuberculum cellae, this is the basion, this is opisthion here, can you all see the anterior arch of atlas and posterior arch of atlas, can you all see the dense and C2, yeah, so pretty simple here. Let’s look at the coronal image, again same, can you all see the jugular tubercles, can you all see the occipital condyle, lateral masses, body of C2, and dense of C2, yeah, okay, one quick question, what is this ligament, can you see this ligament going laterally, anybody can tell me what this is? So next we are going to venture into the ligaments, Which ligament is best seen in the coronal view? correct, this is the alar, audio is a problem, this is the alar, let me pull the mic closer, this is the alar ligament, good, alright, this is not the cruciate ligament, okay, this is alar, jo aise lateral hi jata hai, cruciate should be cruciate, no, it should be cross, this is lateral, aise slanting, that is how you will remember alar. So now let’s venture into the ligaments, before just for your theory purposes CVJ will most of the time come as a theory answer, I haven’t seen anybody being so unlucky to get a long case in their final exam from CVJ, that is pure bad luck, if you are very very unlucky you will get, otherwise you usually don’t get that, okay, so plane radiographs are the ones which we don’t really do nowadays because it can show us very very severe anomalies but minor anomalies we will miss, so we don’t really use it, we can use it as a preliminary investigation in trauma if we don’t have anything else, so lateral and AP are the two minimum views we want and we usually do an open mouth for the odontoid, in trauma we wouldn’t do flexion extension but if you have a congenital case where you are suspecting dislocation, atlantoaxial dislocation, then only we will do flexion extension views on x-ray, okay.
For a CT scan, it is the best investigation to show us the bony anatomy, to pick up congenital anomalies and throughout this lecture we are going to talk about CT. MRI, two things only, it tells us about the ligaments which CT can’t, and it tells us about the spinal cord which CT can’t, a lot of times in the spinal cord we will have compression and this is how all of these CVJ are going to present, they’re going to present with occult, either it’s occult neck pain or if there is spinal cord compression then they’re going to present with spastic paralysis, right, so that’s how they’re going to present, very sudden presentation when the cervical-medullary junction gets compressed, so you have the history for a long time they would have neck pain and then suddenly there is spastic paralysis, that’s how these guys tend to present. So MRI is mainly cord and ligaments, right, flexion extension MRI can be done again congenital atlantoaxial dislocation, we can do that, okay, so this is the role of different investigations.
Let’s go on to ligamentous anatomy. So now we’ll do this in parts, okay, first look here, here what we have are the ACT structures, how you’re going to remember is ACT, okay, ACT, interior most are the smallest most useless ligament, flexion-extension MRI or flexion-extension X-ray both of them have only one role which is to pick up atlantoaxial dislocation, okay, I’ll talk about that once we go forward, it is the most sensitive investigation to pick up atlantoaxial dislocation, so that is what is the role of any dynamic X-ray or MRI.
Yes, Hirayama MRI, I was about to say that, Hirayama is a very rare indication where we will do flexion-extension MRI, that’s the only indication, that’s the only disease that is picked up on flexion-extension MRI, yeah, Hirayama disease, okay.
So we have ACT, so A is the apical ligament, which is the most useless ligament and has the least role in stability, then we have the cruciate ligament behind it which is the most useful ligament, it is the primary stabilizer as the name says cruciate, so it has the vertical band that I see on sagittal and it has transverse bands which I will then see on axial and coronal, okay, so what you will remember cruciate as the name says has a vertical limb which I’m going to appreciate on sagittal and then I’m going to appreciate the transverse part of it on the axial view, okay, so this is the most important. Then look at this, the ALL, anterior longitudinal ligament is going to continue superiorly as anterior atlanto-occipital membrane, this is the posterior longitudinal ligament, PLL superiorly continues as this T here, tectorial membrane, okay, so not posterior atlanto, that is what you have to remember, so tectorial membrane is the superior continuation of PLL, it’s one of the notochordal remnants if you remember. Then we have ligamentum flavum, ligamentum flavum here is going to continue as the posterior atlanto-occipital ligament, so ligamentum flavum continues as posterior atlanto-occipital ligament, behind we have the interspinous ligament, the supraspinous ligament which continues as ligamentum nucae, nuchal ligament, yeah, so this is the continuation.
Should I repeat one more time? ALL, anterior atlanto-occipital ligament, PLL, tectorial membrane, ligamentum flavum continue as posterior atlanto-occipital ligament and your supraspinous continues as ligamentum nucae, so these are your ligaments. So continuation you remember separately and ACT you remember separately. Out of all of these, what are the primary stabilizers?
You can watch this insightful session on the eConceptual app and learn more about the Conceptual Radiology click here: Conceptual Radiology.
