Cervical vertebrae

The cervical vertebrae (Latin: vertebrae cervicales) are seven vertebrae (C1 - C7) located in the neck, and they form the cervical part of the spine extending between the skull and rib cage. The cervical vertebrae are subdivided into two groups - typical and atypical vertebrae - depending on their characteristic features.

The most typical feature of all cervical vertebrae is the presence of the transverse foramen that is formed by the fusion of the rib rudiments and transverse processes. The transverse process contains two eminences called the tubercles - anterior and posterior. Between both tubercles is formed a groove that lodges the spinal nerves.

The typical cervical vertebrae (C3 - C5) are characterized mainly by their small size and presence of a transverse foramen. Their spinal processes typically appear short and bifid. The atlas (C1), axis (C2), sixth vertebra (C6) and vertebra prominens (C7) are considered atypical cervical vertebrae because of their distinguishing features described below.


Atlas (C1)

The first cervical vertebra is also known as the atlas (C1). It articulates with the occipital bone of the skull at the atlantooccipital joint and with the second cervical vertebra - axis - at the lateral and median atlantoaxial joints. The major distinguishing feature of the atlas is the lack of a vertebral body, but instead, it has two arches - anterior and posterior arches.

The atlas appears ring-shaped when viewed from above. It has two lateral masses interconnected by both arches. Lateral masses are formed by the articular processes, and they contain two articular surfaces - superior and inferior. Superiorly each lateral mass articulates with an occipital condyle at the atlantooccipital joint.

The posterior surface of the anterior arch has an impression for the dens of the second cervical vertebra, and the impression contains a facet for dens. The anterior surface of the posterior arch has a groove for vertebral artery. The transverse processes of the atlas are large and project laterally further compared to other cervical vertebrae.


Axis (C2)

The axis (C2) is the second cervical vertebra characterized by all landmarks found on the typical vertebra and a large tooth-like projection called the dens extending superiorly from the vertebral body. The anterior surface of the dens is an articular surface as it articulates with the anterior arch of the atlas forming the median atlantoaxial joint. Two superolateral surfaces of the dens have impressions that serve as attachment sites for alar ligaments.


Sixth cervical vertebra (C6)

The sixth cervical vertebra (C6) is also considered an atypical vertebra.  Besides all the typical anatomical landmarks, it presents a large and well-developed anterior tubercle of the transverse process named the carotid tubercle. It has such a name because the common carotid artery can be compressed against it.


Vertebra prominens (C7)

The seventh cervical vertebra is called the vertebra prominens (C7). It is very similar to a typical vertebra but has some distinct features and thus is considered an atypical vertebra. Its main distinguishing feature is its spinous process - it is longer compared to other cervical vertebrae and is not bifid. The spinous process of the vertebra prominens is easily palpable.