What is the cervical spine?
The cervical spine (human) consists of seven cervical vertebrae (cervical vertebrae, C1-C7), which are positioned between the head and the thoracic spine. Like the lumbar spine, it has a physiological forward curvature (lordosis).
Upper and lower cervical joint
The first cervical vertebra is called the atlas, the second is the axis vertebra. Together with the base of the skull, they form the two upper and lower cervical joints.
The upper upper cervical joint is the connection between the occipital bone and the first cervical vertebra (articulatioatlantooccipitalis), more precisely with the upper joint surface of the atlas. This connection is surrounded by a flaccid joint capsule and is secured by ligaments between the occipital foramen and the anterior and posterior arch of the atlas. The posterior ligament inhibits the nodding movement of the head. The range of movement (forward and backward movement) of this joint of the cervical spine is around 20 degrees, and a slight lateral tilt of the head is also possible.
In the lower head joint, the first cervical vertebra (atlas) rotates together with the head around the tooth (dens) of the axis vertebra. This joint consists of three separate joints:
- the first between the tooth of the axis vertebra, the anterior arch of the first cervical vertebra and a ligament in the atlas
Together with a thin joint capsule, these three joints of the cervical spine allow a range of movement of the head of 30 degrees to the right and left.
Structure of the cervical vertebrae
All vertebrae of the spinal column are basically structured according to a uniform basic pattern. The basic shape of all vertebrae is a ring or hollow cylinder, the front part of which – with the exception of the first and second cervical vertebrae – is a solid, cylindrical bone with a base plate and a top plate. This so-called vertebral body (corpus vertebrae) is smaller in the vertebrae of the cervical spine than in the rest of the spine, as the cervical spine only has to support the head.
The first cervical vertebra (atlas), which carries the head, has a special shape – it does not have a vertebral body as described above, but has a ring shape with a short anterior and a long posterior arch. Thick lateral parts become strongly protruding transverse processes, which increase the effectiveness of the attached muscles that turn the head.
The vertebral foramen – the hole in the bony ring of the vertebrae that forms the vertebral canal (canalis vertebralis) in all vertebrae together, in which the spinal cord (medullaspinalis) and the surrounding spinal meninges run from the brain down to the sacral region – is wider in the cervical spine and has the shape of a triangle with rounded corners.
The spinous processes that extend backwards from the vertebrae are short in the cervical spine and, with the exception of the seventh cervical vertebra, are bifurcated. The spinous process of the seventh cervical vertebra is longer than the others (vertebraprominous) and protrudes slightly.
Spinal cord nerves in the area of the cervical spine
The transverse processes in the area of the cervical spine are divided into two cusps at their ends, which have a groove in the upper area in which eight spinal cord nerves (nervi spinales) run on each side. The upper four nerves (C1-C4 – cervical plexus) supply the neck and its musculature as well as the diaphragm.
A further four cervical nerves emerge from the cervical vertebrae C5-C7 (there are seven cervical vertebrae, but eight cervical nerves!). Together with the nerves of the first thoracic vertebra (Th1), they supply the brachial plexus, which innervates the chest and arm muscles as well as the skin of this area.
Between the cervical vertebrae – as in the rest of the spine – there are intervertebral discs. The cervical spine is supported by ligaments and the neck and back muscles.
What is the function of the cervical spine?
The cervical spine supports the skull and allows it to move. The two head joints between the base of the skull and the two cervical vertebrae, the atlas and axis, provide around 70 percent of the mobility of the head in relation to the trunk.
The body bends forward, particularly via a transverse axis in the cervical spine (and the lumbar spine). The possibility of stretching and bending backwards is particularly great between the lower cervical vertebrae.
Lateral bending is possible in the cervical spine to about the same extent as in the lumbar spine.
Rotation around the vertical axis is possible to the greatest extent in the cervical region, as the head with its main sensory organs, the eye and ear, requires as much mobility as possible. The possibility of rotation around the vertical axis decreases progressively from the head downwards.
The upper joint surface of the axis vertebra allows the first cervical vertebra (atlas) and therefore also the head to rotate strongly due to its outward and downward inclination.
Where is the cervical spine located?
What problems can the cervical spine cause?
If the spinal cord is injured at the level of the fourth vertebral body (or higher), independent breathing is no longer possible. This is because spinal nerves that supply the diaphragm, among other things, are injured.
In addition, there are numerous changes to the (cervical) spine that can be congenital or acquired and often impair its function and stability.
For example, the shape of individual vertebral bodies, vertebral arches or vertebral processes can be altered. The number of vertebrae can also vary. Sometimes, for example, the first cervical vertebra is fused to the occipital bone (atlas assimilation).
Sometimes cervical vertebrae (or other vertebrae) are blocked in their mobility, for example due to muscle spasms.
A herniated disc in the cervical spine is particularly common in older people with signs of wear and tear in the cervical vertebrae. With increasing age, the vertebral joints change and loosen, and the intervertebral discs become increasingly worn down. This can ultimately lead to a slipped disc. The area from the fifth to the sixth (C5/6) and from the sixth to the seventh (C6/7) cervical vertebrae is particularly often affected.
Pain in the cervical spine is generally referred to as cervical spine syndrome. It can, for example, be muscular or caused by nerve irritation, herniated discs or degenerative changes.
