Synonym: vertebral column
The spinal column is an important part of the skeleton, which serves as a movable support of the body and bears the weight of the head, neck, torso and upper extremities. It additionally includes the spinal cord. It is a key anatomical feature of vertebrates.
The individual components constituting the spine are called vertebrae. The 24 vertebrae of the human spine are connected to each other via intervertebral discs and by various ligaments.
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2 Shape of the spine
When viewed from a lateral aspect the human spine has a double S-shape due to
- Lordosis in the neck and lumbar regions: here the spine is curved towards ventral convex
- Kyphosis in thoracic and sacral regions: here the spine is curved towards dorsal concave and toward dorsal convex Seen from a dorsal or ventral perspective the spine is approximately straight. Lateral curvature is described and denoted using the term scoliosis. The physiological curve of the spine is maintained by positional fixation of the vertebrae by ligaments as well as through the active tension of back muscles.
The specific statics of the spine, which is similar to a moving spring rod, allows the upright posture in humans. It dampens shocks arising from leg movements, thereby protecting the brain against severe shocks.
The spine can be divided into 5 sections:
4 Basic structure of the spine
Each vertebra consists of a vertebral body (corpus vertebrae), a vertebral arch (arcus vertebrae) and various extensions (processus vertebrae).
4.1 Vertebral body (corpus vertebrae)
4.2 Vertebral arch (Arcus vertebrae)
- Dorsal extension of the vertebral body
- Surrounds the foramen vertebrale, all foramina together form the spinal canal (canalis vertebralis), which houses the spinal cord and surrounding surfaces
- In the vertebral arch one finds at the exit from the vertebrae, both above and below, a notch (incisura vertebral superior and inferior) which together with the next higher notch forms the formamen intervertebrale, through which the spinal nerves exit
4.3 Vertebral processes (processus vertebrae)
5 Special features of the spinal structure
5.1 1. Cervical vertebra (atlas)
The first cervical vertebra, (atlas) is an annular vertrebra without vertebral bodies and spinous process. The following bones are differentiated:
- Front arch of the atlas (arcus anterior atlantis) with fovea dentis situated on the inside; on the outside lies the tuberculum anteriorius atlantis
- Rear arch of the atlas (arcus posterior atlantis) with spinous process (tuberculum posterius atlantis)
- Massae laterales atlantis between the front arch and rear arch of the atlas the articular surfaces of the atlas are:
- 2 Facies articulares superiores
- 2 Facies articulares inferiores 1 fovea dentis the two facies articulares superiores form together with the occipital bone the atlantal-occipital joint.
5.2 2. Cervical vertebra (axis)
The 2nd cervical vertebra, also called the axis, is the cervical vertebrae with the highest bone mass. Its main feature is the dens axis, which forms together with the atlas the atlantoaxial joint. Its joint surfaces are:
- 1 Facies articularis anterior at the dens
- 1 Facies articularis posterior at the dens
- 2 Facies articular superiores at vertebral arch
- 2 Processus articulares inferiores at the vertebral arch
5.3 Thoracic vertebra
The thoracic vertebrae have as their main feature the joint facet, which articulate with the ribs. Differentiation includes:
The lumbar vertebrae possess a lesser sagittal than transverse diameter. Instead of the transverse processes rib rudiments are found here, the so-called processes costales. The transverse processes themselves exists here as the processus accessorii. At the back of the upper articular processes (processus articulares superiores) one finds the processus mamillares.
5.5 Os sacrum
The 5 sacral vertebrae are fused into forming the triangular sacrum. Differentiation includes:
- Basis ossis sacri: upper part of the os sacrum
- Apex ossis sacri: lower part of the sacrum
- Facies pelvica: front face with lineae transversae and lateral foramina sacralia anteriora
- Facies dorsalis: posterior surface with median sacral crest crista sacralis mediana (equivalent to proc. spinosi), crista sacralis medialis (equivalent to proc. articulares), crista sacralis lateralis (equivalent proc. transversi) and foramina sacralia posteriora
- Pars lateralis: also called ala ossis sacri, with facies auricularis The canalis sacralis is a continuation of the spinal canal (canalis vertebralis). It opens inferiorly in the hiatus sacralis.
5.6 Os coccygis
The coccyx os coccygis forms the lowest part of the spine. It consists of 4-5 coccyx vertebrae connected to one another by synchondroses and synostosised.
6 Intervertebral discs (disci intervertebrales)
The intervertebral discs are discs of fibrocartilage, which lie between the vertebral bodies. They have a collagenous fibrous outer layer, the annulus fibrosis, which surrounds an inner zone of fibrocartilage and a nucleus (nucleus pulposus). The discs together with the vertebral bodies form the symphysis intervertebralis.
7 Ligaments of the spine
- Between the vertebral bodies:
- Between the vertebral arches:
- Between the transverse and spinous processes:
- Between sacrum and coccyx:
8 Blood supply
Venous drainage of the vertebral bodies and the surrounding ligaments occur via the plexus venosus vertebralis externus and plexus venosus vertebralis internus.
Spinal disorders fall within the scope of orthopedics. They can be brought about through Traumatic, degenerative or other causes.