Hello, everyone! This is Joao from Kenhub, and welcome to another anatomy tutorial where, right now, I'm going to be talking about the cervical spine.
And in this tutorial, we will cover the cervical vertebrae which are the vertebrae of the neck, immediately inferior to your skull. We talk about the structure and parts identifiable on the cervical vertebrae on this tutorial. And you can clearly see it here, highlighted in green, on this image.
We will also talk about the overall structure of the bones of the cervical spine as well as some of the ligaments, not many. We will focus on a different tutorial on the different ligaments that we find on this region of the body. But for now, I might just add a couple so you can understand what is happening there.
Now, the cervical vertebrae are the smallest vertebrae in the spinal column. The reason for that would be because these vertebrae are not carrying as much weight as these ones that need to be carrying more weight, for that reason, need to be a little bit bigger—another reason, I have to say, that our body is engineered in a very cool way.
Now, there are, as you can see here on this image, seven cervical vertebrae. The first one, the second, and also here, the seventh has a unique shape, while the third to sixth vertebrae are similar in shape and structure.
We’re going to start off with the very first vertebra here that you see on the screen. This is known as the atlas. And here, we’re not highlighting it because this is the entire bone. And this is... if we look at it from a superior view, this is the first cervical vertebra and the first vertebra in the spinal column.
It is unique in that it lacks a body and a spinal process, and it is the only vertebra that articulates with the skull forming, then, this joint here, the atlanto-occipital joint.
And the atlanto-occipital joint is now seen here, highlighted in green, and is formed between the atlas. And you notice here the first vertebra, the atlas, and also the occipital condyles that you find at the base of the skull on the occipital bone. This joint is a movable joint and better known as a synovial joint.
The next structures that we’re going to highlight here—this is now part of the atlas—this is known as the lateral mass of the atlas.
And the lateral masses of the atlas are thickened portions of the atlas that support the skull. They have an inferior and a superior facet which articulate with and support the occipital condyles and the axis superiorly and inferiorly, respectively.
The next structure that we’re going to be highlighting here, this is known as the anterior arch of the atlas. And the anterior arch of the atlas has an anterior tubercle and a dental fovea. And you can clearly see here the anterior tubercle of the anterior arch of the atlas and also, here, the dental fovea. And the dental fovea articulates with the dent of the axis, also known as the odontoid process of the axis, which is then the second cervical vertebra.
The anterior tubercle provides attachment for the longus colli muscles and the anterior longitudinal ligament.
If we have an anterior arch, we should have, then, this one that you see here, highlighted in green, found posteriorly. And this is the posterior arch of the atlas. And the posterior arch of the atlas has a posterior tubercle as well and a groove for the vertebral artery, and they’re not really seen here on this image.
The posterior tubercle is a rudiment of a spinous process, and it provides attachment to several structures including the rectus capitis posterior minor muscle and the nuchal ligament.
We are now ready to move on to the second cervical vertebra known as the axis. And this one has an odontoid process that articulates with the atlas, and you can see here on this image. Now, this is the full axis, not being highlighted. And this is the axis articulating with the first cervical vertebra, also known, then, as the atlas. And you notice here the odontoid process articulating with the atlas.
The axis has a small transverse process which houses the foramen transversarium and a large, bifid spinous process.
Since we just mentioned this structure, might as well highlight it and talk a little bit about it. This is known as the odontoid process of the axis. And the odontoid process of the axis has an apex, anterior articulating surface, and a posterior articulating surface. The apical ligament is attached to the apex of the odontoid process.
We’re now going to highlight this structure that you see here on the odontoid process. This is, then, the posterior articular facet of this structure. This articulates with the transverse ligament of the atlas, thereby keeping the axis and the atlas in contact.
Now that we have covered the structures seen on the first and second vertebrae that are unique compared to the rest of the cervical vertebrae, we will look at the general structure of the remaining five cervical vertebrae that are similar in structure to one another.
We’re going to start off with this one that you see here, highlighted in green, which is known as the transverse foramen. And this is an opening found on the transverse process of all the cervical vertebrae. The vertebral artery and vein pass through this foramen.
Another structure that we’re going to be highlighting here is known as the sulcus of the spinal nerve. And the sulcus of the spinal nerve is a groove found on the transverse processes of the third, fourth, fifth, sixth, and seventh cervical vertebrae. And as the name suggests, the spinal nerve passes along the groove as it exits the intervertebral foramina. And you can also see these structures from a lateral view, now seen here highlighted in green.
Now, we’re moving on to the next ones that you see now, highlighted. These are known as the anterior tubercles, and they are bony projections found on all the cervical vertebrae except the atlas.
Now, the longus colli muscles attach to this tubercle that is located anterior to the anterior arch.
We also have these that you see now, highlighted. These are known as the posterior tubercles. The posterior tubercle is a rudiment of a spinous process. It is the bony projection to which the rectus capitis posterior minor muscle attaches to.
Even though this tutorial is focused on the different bony structures that we find on the cervical vertebrae, I would still like to mention a couple of ligaments that are found within the cervical vertebrae… or attached to the cervical vertebrae.
We’re going to start off with this one that you see here, highlighted in green, which is known as the transverse ligament of the atlas. And the transverse ligament of the atlas ensures the odontoid process maintains contact with the atlas. And you can see here the odontoid process of the axis and here then, the articular surface of the atlas. And you notice here that this is definitely reinforcing the contact between these structures.
Now, as you also notice, that this ligament is concave in the front and convex in the back. It is firmly attached on either side to a small tubercle on the medial surface of the lateral masses of the atlas.
The next ligaments that you see here, highlighted in green, are the alar ligaments, which connect the sides of the odontoid process of the axes to the tubercles on the medial side of the occipital condyle.