Spinal column

The spine consists of 24 movable vertebrae as well as the crura and tailbone. Read more about the spine: structure and function!

Spinal column

The spinal column is the backbone, support and moving axis of the trunk in humans and vertebrates. It is connected to various parts of the skeleton (head, pelvis, arms, etc.) and encloses the spinal cord. Read all important information about the spine: structure, function and important diseases and injuries!

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spinal column

  • What is the spine?

  • What is the function of the spine?

  • Where is the spine?

  • What problems can the spine cause?

What is the spine?

The spine is the bony axis skeleton that carries the trunk and allows its movements. She is straight from the front. Viewed from the side, on the other hand, it has a double S-shape:

In the neck and lumbar region, it is curved forward (cervical and lumbar lordosis), in the thoracic and sacral region, it is curved backwards (breast and sacral kyphosis). This spine anatomy is important for standing upright and walking, as well as cushioning burdens.

How many vertebrae does a human have?

The human spine consists of 33 to 34 vertebrae. It is divided into five spinal sections, each consisting of several vertebrae:

Cervical spine (cervical spine)

It is composed of the seven seven cervical vertebrae (cervical vertebra, C1-C7). Read more about this uppermost section of the spine in the post cervical spine.

Thoracic spine (BWS)

More about the longest section of the spine, which is made up of the 12 thoracic vertebrae (thoracic vertebrae, Th1 - Th12), read in the article on the thoracic spine.

Lumbar spine (LWS)

The third spine section consists of five vertebrae (lumbar vertebra, L1 - L5). Find out more about this in the article lumbar spine.

Sacrum (Os sacrum)

During development, the five sacral vertebrae (sacral vertebra, S1-S5) grow together into a single bone. Read more about it in the article Kreuzbein.

Tailbone (Os coccygis)

The last part of the spine, too, consists of fused vertebrae, four to five in number. Find out more in the article Coccyx.

The 24 cervical, thoracic and lumbar vertebrae remain mobile for life - except in case of illness or injury.

The vortex structure varies

The vortices are basically built according to a uniform basic scheme. However, in the various spine sections there is a somewhat varying structure in adaptation to the function and load: vertebrae that perform more static functions differ in size and shape from those that have increasingly dynamic tasks.

Therefore, the vertebrae of the cervical spine, which carry only relatively little weight with the head, but must allow for a great mobility, shaped differently and smaller than the lumbar vertebrae. The latter must carry a significantly greater weight and therefore be stronger, but allow only a smaller range of motion.

The vertebral body

The basic form of all vertebrae is a ring or hollow cylinder. The anterior part of each vertebra - with the exception of the first and second cervical vertebrae - is a solid, cylindrically shaped bone with a basal and a cover plate, the vertebral body (corpus vertebrae).

The vertebral body is the actual supporting and supporting part of the spine. He has a thin compact outer layer and inside a strong spongiosa, a spongy system of fine trabeculae, which is filled with red bone marrow. The central area of ​​the upper and lower surfaces of the vertebral bodies is porous, and only the marginal ridges are made of solid bone.

Only the first cervical vertebra (atlas) that carries the head has no vertebral body. It is connected to the second vertebral body (Axis) via a joint (Articulatio atlantoaxialis).

The intervertebral discs

Between each two adjacent vertebral bodies are pressure-elastic intervertebral discs of cartilaginous tissue, the intervertebral discs. Read more about it in the article Intervertebral disc.

The vertebral arch and the appendages

The posterior part of each vertebra is the vertebral arch (arcus vertebrae), which is narrower and weaker than the vertebral body. From the vertebral arch go from several extensions:

These include four articular processes (processus articulares), two of which are directed upwards and two downwards. They form the real joints between the vertebrae. The paired transverse process (plural: Processus transversi) goes off to the right and left of the vertebral arch and serves as a lever arm for attaching muscles. The ribs attach to the vertebral arches of the thoracic spine (Th2 to Th10). A single spinous process (processus spinosus) goes backwards.

Spinous process

Read more about this spinous process in the article spinous process.

Bands for stabilization

Between the vertebral arches - from the second cervical vertebra down to the first sacral vertebrae - bands of elastic connective tissue are stretched (ligamenta flava), which together with muscles stabilize the spine. Their thickness increases from top to bottom.

These ligaments of the spine begin laterally in the interior of the spinal canal in the anterior region at the level of the articular processes, then pull backwards to the spinous process, where they meet and the intervertebral space delineates to the rear.

The spinal canal

The hole in the bony ring of vertebrae is the vortex hole. All vertebral holes together form the vertebral canal (vertebral canal), where the spinal cord (medulla spinalis), with the surrounding spinal cord skins, runs from the brain down to the sacral region. The spinal canal is becoming narrower from top to bottom, because the spinal cord is getting narrower downwards.

What is the function of the spine?

The function of the spine is to stabilize the trunk, to ensure an upright posture and the greatest possible mobility. The spine also provides the spinal cord with bony protection against injury.

Due to the double-S-shaped curvature of the spine, shocks that act on the spine during jumps, while walking or falling on the feet can be intercepted. The pressure wave is not passed on to the head and the sensitive brain. Due to the posterior curvature (kyphosis) of the thoracic spine, the lordosis of the lumbar spine and the bending of the lumbar spine against the sacrum, the center of gravity of the body is above the feet, allowing a stable upright posture.

The necessary balance, when the stomach becomes too thick and heavy and lumbar lordosis increases, can be seen on pregnant women, who move their chest, neck and head back to compensate.

The ligaments between the vertebral arches (ligamenta flava) are stretched when the spine is flexed and help the back muscles with their pre-straightening tension.

The mobility of the spine

The mobility between the individual vertebrae is relatively low. But the total range of motion that results from the chain of vertebrae is very large. The possibilities of the spine to change in shape lie in all levels of the room and are reinforced by the combination of different movements.

A prevention of the body takes place especially on a transverse axis in the cervical and lumbar spine, wherein in the latter bending is possible to a lesser extent than the stretching to the rear. In contrast, in the thoracic spine, the possibility of diffraction is significantly greater than that of extension. The possibility of stretching and flexing backwards is particularly great between the lower cervical vertebrae, the eleventh thoracic and the first lumbar vertebra, and between the fourth lumbar vertebra and the sacrum.

A sideways tilt is about equally possible in the cervical and lumbar spine. It is the largest in the thoracic spine and is limited only by the ligaments of the spine and the ribs.

A rotation about the vertical axis is possible furthest in the neck area, since the head with its main internal organs eye and ear needs the greatest possible flexibility. The possibility of rotation about the vertical axis decreases progressively downwards and is lowest in the lumbar spine.

Where is the spine?

The spine is located in the back of the body when viewed in the cross section of the trunk. The processes of the individual vertebrae lie close together under the skin of the back, where they can be seen and felt by slender humans.

What problems can the spine cause?

Congenital or acquired spinal changes may interfere with their function. For example, individual vertebral bodies, vertebral arches or spinous processes may be changed in shape. Sometimes the number of vertebrae varies:

If, for example, the first cervical vertebra has grown together with the occipital bone, it is called atlasassimilation. If there is an additional (sixth) lumbar vertebra, this is called lumbarisation. When the last (fifth) lumbar vertebra is fused with the sacrum, there is sacralization.

Due to muscle tension or other causes, individual vertebrae may be blocked in their mobility.

The term spina bifida ("open back") refers to a congenital malformation of the spine or the spinal cord: The embryonic neural tube, from which the spine and spinal cord develop, normally closes completely. In a spina bifida this closure is incomplete.

Scheuermann's disease is a congenital disease of the thoracic and lumbar spine that manifests in adolescence. The vertebral bodies become wedge-shaped by unilateral flattening and thus contribute to the formation of a hump (kyphosis, round back) - usually in the area of ​​the thoracic spine.In addition, irregular cartilaginous nodules (Schmorian cartilaginous nodules) form on the end plates of the vertebrae. A slight hump, back pain, and restricted movement in the affected portion of the spine are signs of the condition.

A lateral curvature of the spine, which may also be twisted in itself, is called scoliosis.

Ankylosing spondylitis (Ankylosing spondylarthritis) is a chronic, progressive, rheumatic disease in which the joints of the ankylosing spondylitis spinal column and the sacral iliac joints are inflamed.

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