 Good day everybody. This is Dr. Sanjay Sanyal, Professor Department Chair. This is going to be a demonstration of a typical cervical vertebra with some of its important clinical correlations. So the vertebra that you see in front of you, this is a typical cervical vertebra. So what are the characteristic features of a typical cervical vertebra? First of all, we can see this foreman here. This is known as the transverse foreman or in Latin, the foreman transversarium. It is very typical of a cervical vertebra and we should be able to identify a cervical vertebra from distance by just looking at the transverse foreman. The next feature that we see for typical cervical vertebra are these projections on the lateral aspects of the vertebral body on the superior aspect only. They are referred to as the onsenate process or the angus. And the third thing that we see is the bifid spinous process which is on the under surface. And of course the vertebral foreman is very big and it's triangular shaped because it has to encompass the cervical enlargement of the spinal cord. So let's come back to this transverse foreman. This transverse foreman gives passage to a very important artery that is the vertebral artery. And I shall show you the vertebral artery passing through the transverse foreman just a little while later. In order to understand the transverse foreman just imagine that this is like a square. So therefore it's got an anterior margin, a lateral margin, a posterior margin and a medial margin. The anterior margin is formed by a primordial what is known as a costal element. And the posterior margin is formed by a primordial what is known as the transverse element. And the two of them constitute the transverse process of a cervical vertebra. This costal element is the one which is responsible for forming the true ribs in the thoracic region. But in this region it forms part of the transverse process. And the two elements the costal element and the transverse element they are united by this bridge. This is referred to as the costal transverse bar. And if you look at the costal transverse bar you can see there's a smooth depression here which gives passage to the ventro tremors of the spinal nerve. And the fourth margin of the transverse foreman is this one here. This is the pedicle which gives attachment to the vertebral arch that is the lamina and the spinal process. This transverse foreman as I said gives passage to the vertebral artery. And the vertebral artery along with the sympathetic plexus and some veins. This transverse foreman is small or absent in C7 but it's present from C650321. And as the vertebral artery climbs up it goes across the posterior arch of atlas and it enters through the posterior gland occipital membrane and it supplies the posterior half the cerebral circulation. Here we can have an important clinical correlation when we do vigorous manipulation of the neck. Like for example chiropractic manipulation and it has been documented that can sometimes lead to dissecting aneurysm of either one or both sides vertebral artery with occlusion. When the vertebral artery is passing through the transverse foreman this is the second part of the vertebral artery. The first part being the cervical part. This part is known as the vertebral part. And here it gives branches spinal branches which enter through the intervertebral foreman and supplies the spinal cord. The spinal nerve comes out from here. The ventral ramus travels like this behind the vertebral artery and the dorsal ramus goes across the transverse element and it supplies the posterior aspect. Now let's come to the vertebral anchors. The anchors forms what is known as the ancho vertebral joint. It's a sanomial joint which is located postrolateral to the fibrous joint cartilaginous joint formed by the intervertebral disc. That is one of the reasons why the cervical vertebra is so mobile. Talking about the mobility of the cervical vertebra brings me to this articular fasus that we see here. The articular fasus of the cervical vertebra are directed super posteriorly. The superior articular fasus are directed super posteriorly and the inferior articular fasus are directed info anteriorly. And because of this unique articulation cervical region is so mobile. That brings me to some important clinical correlations pertaining to the cervical vertebrae because of its mobility. We can get excessive friction injury of the cervical vertebra. And for that let me show you a fully articulated cervical skeleton. So here in front of us we can see a fully articulated cervical skeleton. And we can see that this is the vertebral joint and we can see the vertebral arteries passing through the transverse pheromone. And we can see the spinal nerves are coming out. This is anterior arch of the atlas. Below that is the axis. This is C3, C4, C5, C6, C7. We see that the vertebral artery does not pass through the transverse pheromone of C7. Instead it passes through C6, 5, 4, 3, 2, 1. And then it makes a posterior curve. And you can see that posterior curve here. And it goes across the posterior arch of atlas. And it pierces the posterior atlantoxical membrane. And it enters into the cranial cavity. If we have excessive friction injury of the cervical spine, then we can get subluxation and dislocation of the cervical vertebrae. And they have been classified in two stages 1, 2, 3, 4, depending on how much of the vertebra above has slid back on the vertebra below. If it's just a tear of the ligament, it is stage one. If it is 25% translation, it is stage two. If it's 50% translation, it's stage three. And if it's more than 50% up to 75% or 100% translation, that means the vertebra above has completely shifted away from the vertebra below, then it is stage four, which is associated with facet jumping. This is a lateral luxury of the cervical spine showing stage three, flexion injury, 50% translation. We can also get extension injury of the vertebra, the cervical region. And here again, we can have two tabs. One is extension of the head itself. And that produces a fracture of C2 vertebra. And where that fracture occurs, for that, I shall show you in this specimen here. This is a specimen of C2 vertebra. And we can see, we can recognize the C2 vertebra by virtue of its autonomic process or the dense. The C2 vertebra, when it fractures, it fractures just posterior to the transverse for MN, between the superior and the inferior articular facet. And that is referred to as traumatic spondylosis. This fracture line goes across like this. It is between the superior and the inferior articular facets. And that is what produces, what is known as hangman's fracture. And it produces death by spinal cord, compression or even transaction at the level of third cervical spinal segment. This is a lateral luxury of the cervical spine showing fracture, traumatic spondylolisis of C2. That's a hangman's fracture. If we have extension of the head as well as the neck, then it can be what is known as a whiplash injury. And that can produce a central cord syndrome. That brings me to yet another important clinical correlation pertaining to the cervical spine. The lower part of the cervical spine, especially C5, C6, C7. This is the region where the cervical spine merges into the thoracic spine. So therefore, this is the region of junction between the mobile part of the cervical spine and the fixed part of the thoracic spine. So therefore, we can get herniation of the nucleus pulposus between C5, C6, or between C6, C7, between C7, T1. And when this herniation of the nucleus pulposus occurs, it usually herniates postural laterally. And then it compresses on the spinal nerve root. In this juncture, we should remember that in the cervical region, there are seven cervical vertebrae, but there are eight cervical spinal nerves. So therefore, each segment, the spinal nerve goes above the corresponding vertebra, except C8, which comes out below C7, that is above T1. So therefore, in a herniation of nucleus pulposus, herniating nucleus pulposus compresses on the spinal nerve with a higher numerical value. In other words, if there's a herniation between C6, C7, it compresses on the C7 spinal nerve, and so on and so forth. This is a lateral MRI of the cervical spine showing a herniation of the nucleus pulposus. I wanted to mention one more important clinical correlation pertaining to the atlas. This is the atlas in front of you. The atlas, we can see, does not have a body, whether it has a spinal process. Instead, it has got an anterior arch and a posterior arch. This is the anterior tubercle of the anterior arch, the posterior tubercle of the posterior arch. It has got a lateral mass to which is attached to the transverse ligament of atlas. This is the place which is occupied by the dense of the axis, which actually embryologically, developmentally, belongs to the body, but which got fused with the axis. And here we have the transverse process, and we can see the transverse foremen. On the posterior atlas, we can see the smooth portion. This is the portion where the vertebral artery comes back through the transverse foremen, and here it pierces the posterior gland occipital membrane, and it enters into the cranial cavity. So this is the region of the suboccipital triangle. If there's a force from above hitting the skull, then the atlas fractures into four fragments. One piece goes across like this, another fragment goes like this, another fracture line goes like this, across the posterior, and the fourth fracture line goes across like this. So therefore, atlas fragments into four pieces. One piece, a second piece, a third piece, and a fourth piece. And the four fragments move outwards. They do not compress the spinal cord. And that is referred to as a Jefferson's burst fracture. So this is a CT scan of a C1 atlas vertebra to show Jefferson burst fracture into four fragments. These are some of the points which I want to mention to you about the cervical vertebra with its important clinical correlations. Thank you very much for watching. Dr. Sanjay Sanyal, Sanyal. If you have any questions or comments, please put them in the comment section below. Have a nice day.