(2.24)

Now we’ll look at the ligaments which hold the odontoid process in place, making it the stable pivot round which rotation of the head occurs. We’ll see the transverse ligament of the atlas, the cruciform ligament (which the transverse ligament is part of), and the alar ligaments. To see them, we’ll go back to the previous rear view, and remove the tectorial membrane.

Directlly beneath the tectorial membrane is this strong and important ligament, the transverse ligament of the atlas. The transverse ligament is attached on each side to these two tubercles on the atlas. The transverse ligament prevents the odontoid process from being displaced backwards.

A slender ligament, the superior band, runs upward from the transverse ligament to the base of the occiput, another one, the inferior band runs downward to the body of the axis. These, along with the transverse ligament of the atlas, are referred to collectively as the cruciform ligament.

We’ll remove all of the cruciform ligament to see the odontoid process and the alar ligaments. Here’s the odontoid process. Here are the massive alar ligaments. They pass from here on the odontoid process, to here on the inside of the occipital condyles. The alar ligaments limit rotation of the head, specially in lateral flexion.

Here’s the side view again. Here’s the tectorial membrane, here in front of it is the divided transverse ligament of the atlas. It’s quite an impressive structure.

Lastly, we’ll look at the ligaments that connect the vertebral arches. The arches of the regular cervical vertebrae are held together by strips of yellow fibrocartilage, known collectively as the ligamentum flavum.

The arches of the axis and the atlas, and the edges of the foramen magnum are held together by these loose and flexible sleeves of fibrous tissue, the atlanto-occipital and atlanto-axial ligaments.