The back: here’s how it’s built

Berlin, 15.03.2020 – With its double S-shaped spine, strong muscles and stable ligaments, the back performs an important function without which our human life would not be possible: the back enables us to walk upright. It therefore makes us unique among all living beings.

How the spine works?

The spine forms the center of our body. It connects different parts of the skeleton with each other and can be divided into different sections based on the bony vertebrae:the cervical spine, the thoracic spine and the lumbar spine, as well as the sacrum and the coccyx. The spinal column enables us to walk upright due to its special structure and shape. It is curved in a double s-shape, which allows it to be dipped like a spring and cushion everyday movements.

Elastic discs between the vertebrae act as additional shock absorbers and provide mobility. Similar to a bulging water cushion, held by an outer, firm fibrous ring, the gel-like intervertebral discs push the individual vertebrae apart. While they usually lose fluid in the course of the day due to stress, fluid flows back again when the load is relieved. This provides the intervertebral discs with nutrients.

The vertebrae have a hole inside them and form the spinal canal. In its protection runs the spinal cord, through which signals from the brain into the body
and back. Your hold gets the spine by a variety of ligaments and muscles. The bands connect the bones together. In interaction with the back muscles, they enable us to move in all directions.

How is the spinal column structured? Put in the info basket

The human spine extends from the back of the head to the coccyx and can be divided into five sections: the cervical spine, the thoracic spine, the lumbar spine, and the sacrum and coccyx. In most people, the spine consists of 33 individual vertebrae, but the number may vary from person to person.

If you look at the spinal column from the front, it appears straight. Viewed from the side, it can be seen that it is curved four times (double S-shape). These curvatures cushion loads during upright walking.

Did you already know?

Almost all mammal species – from giraffes to mice – have exactly seven cervical vertebrae. One of the exceptions to this rule are the sloths. They have eight to ten vertebrae in the neck.

How is a vertebra structured? Put in the info basket

The vertebrae of the cervical, thoracic and lumbar spine are similar in structure except for the first and second cervical vertebrae. A vertebra consists of a vertebral body and a vertebral arch, including a spinous process, two transverse processes and four articular processes.

Despite their similar basic structure, the vertebrae have certain characteristics depending on the section of the spinal column they are in. How does z. B. the vertebral body width and height increase from top to bottom as the vertebrae in the lower part of the spine must bear the greatest weight.

The dorsal surface of the vertebral body and the vertebral arch together form the vertebral foramen (foramen vertebrale). Together, the vertebral holes (with intervertebral discs and ligaments) form the spinal canal through which the spinal cord passes. The processes of the vertebrae serve the attachment of ligaments and muscles and the connection of adjacent vertebrae. At the level of the thoracic spine, the lateral transverse processes form the rib-vertebral joints.

At the transition between the vertebral arch and the vertebral body, there are recesses on the upper and lower sides of the vertebral arch. Adjacent vertebrae thus form the so-called intervertebral hole. The spinal nerves emerge from the spinal canal through the holes on both sides of the spine. The spinal nerves receive signals from the body and transmit them to the central nervous system (spinal cord, brain). On the other hand, spinal nerves transmit signals from the central nervous system to the organs of the body (z. B. the command to lift the foot to the muscles of the leg).

The spine is divided into movement units. A unit consists of two vertebrae with intervertebral disc, vertebral joints, ligaments and muscles between them. The mobility of the spinal column (forward, backward, sideways inclination and rotation) results from the complex interaction of the various segments.

Are the intervertebral discs to blame?

When the lower back suddenly hurts, some people think of a herniated disc. In fact, only about 4 out of 100 back pain patients are diagnosed with disc problems as the cause of their complaints.

What are the intervertebral discs for?? Put in the info basket

An intervertebral disc is located between each vertebral body. It consists of a fibrous ring that is firmly attached to the vertebral body above and below it and a gelatinous, almost fluid core. The intervertebral discs ensure that when the spine is subjected to uneven stress – e.g. B. during flexion – the pressure is distributed fairly evenly and thus protect the vertebral bodies from uneven wear and tear. Intervertebral discs are not supplied with blood. They are nourished by the surrounding tissue and blood vessels.

Intervertebral discs can regenerate to a certain extent, which can also be observed on a daily basis: In the morning, the intervertebral discs are higher and filled with more fluid; in the evening, they have lost water content, among other things due to the upright gait.

If the back wears out?

Some wear and tear of the intervertebral discs is normal with age. The extent to which intervertebral discs are damaged over the course of a person’s life also depends on the extent to which they have previously been exposed to incorrect loads. In general, however, it can be said that the back does not wear out if you use it frequently in everyday life. Movement and moderate stress make the back stronger.

What role do nerves play in the functioning of the spine?

The components of the spinal column are supplied by branches from the spinal cord nerves. These form a dense network. In almost all parts, as in other tissues, free nerve endings have been found that can receive pain stimuli (nociceptors).

How do ligaments stabilize the spine? Add to info basket

The various mobile elements of the spine are held together and stabilized by a multitude of ligaments. Three are particularly important: The anterior longitudinal ligament is a strong ligament at the front of the vertebral bodies – it prevents the spine from bending backwards too much. Ligaments between the spinous processes at the back of the vertebrae prevent excessive forward flexion. And finally, strong elastic ligaments prevent the vertebral bodies from shifting against each other.

Does slouching cause back pain?

"Sit straight!" – who has not heard this admonition before? But in fact you don’t get back pain from a slouching sitting posture. Even when lifting, according to new findings, it makes no difference whether you carry loads with a straight or curved back.

How is the back musculature structured? Add to info basket

The back musculature consists of deep and superficial muscles. The deep-seated muscles connect the individual elements of the spine. They ensure the erection and stability of the spine and enable flexion, extension, lateral inclination and rotation of the back. The musculature is very strong and designed for endurance performance. This allows an upright posture to be maintained over a long period of time. Superficial muscles also play an important role in stabilizing the spine by supporting the functions of deep back muscles.

Another muscle group that contributes to stabilizing the back is the abdominal musculature, which assists the stabilizing function of the back muscles, especially during lateral and twisting movements. Gravity pushes the spine forward in the standing position. To compensate, the back muscles must pull on the spine to straighten it up.

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