Many underestimate the importance of the skeleton and, in particular, the spine. However, this is not worth doing, because it plays a very important role in human life. It is he who supports the person in an upright state, in addition, he serves as a support for muscle tissues and organs, forms the walls of the chest and abdominal cavity. The structure of the spine allows it to withstand enormous loads, while it retains its flexibility and mobility. In general, when you start to ponder over the structure of one or another organ, especially the spine, each time you are struck by the wisdom of nature.
The scheme of the spine, in general, is simple and ingenious in its own way. It consists of 32 vertebrae, and by structure and purpose it is divided into 4 departments: sacral, lumbar, thoracic and cervical. One of the structural features of different parts of the spine is that each of its departments has a bend forward or backward. The directions of the bend alternate in pairs: the cervical bends forward, such bends are called lordoses, the thoracic backward, such a bend is called kyphosis, and so on. This structure of the spine allows it to withstand enormous loads, because it looks like a spring, which plays the role of a shock absorber, softening the load when walking and running.
Each vertebra, except for the first cervical, but more on that later, consists of a body and an arc. The arc forms a hole in the vertebra. Together, these holes form a cavity inside the spine, in which, under the reliable protection of bone tissue, the spinal cord is located. In addition, each vertebra has several paired and non-paired. They, together with the intervertebral discs and ligaments, provide traction of the vertebrae.
Now let's talk about each department individually. It’s worth starting, of course, with the neck. It includes only 7 vertebrae. The size of the cervical vertebrae is much smaller than all the others. In general, the size of the vertebrae increases as you approach the coccyx. This is necessary to compensate for the increasing load.
But back to the cervical vertebrae. I must say that their structure is the most diverse. The first vertebra is the most different from the others; it is called the atlas. It has no body at all, consists of arcs and processes. The second one already has a body, but it also differs from other cervical vertebrae by the presence of a large process called a tooth. This process is the axis around which the head rotates. On the sides of all cervical vertebrae, rudimentary costal processes can be seen. They are most pronounced in the 6th vertebra. The hole formed by the arch of the cervical vertebrae has a triangular shape.
The vertebrae of the thoracic region have a larger body, the shape of the hole changes to round, on the transverse process of the vertebrae of the thoracic region there are costal fossae.
We continue to consider the structure of the spine. The next section is the lumbar. There is another increase in the size of the vertebral body. In addition, the lumbar vertebrae differ in the horizontal arrangement of its processes. The hole size is much smaller.
The vertebrae of the sacral section are divided only up to the age of 25, by this time they are fused. The resulting bone is called the sacrum and has a triangular shape. It is part of the pelvis.
The lumbosacral spine is distinguished from the rest by the massive size of the vertebrae. After all, it is precisely these parts that account for the greatest load.
Considering the structure of the spine, it is simply impossible to lose sight of the intervertebral discs. They perform several functions at once: they connect the vertebrae and provide mobility of the spine. This multifunctionality is achieved due to the unique structure. The disk consists of two parts: the nucleus, which is based on solid cartilage, and a dense ring of connective tissue. The cartilage takes on the main load, and the ring surrounding it compensates for it.
In general terms, the structure of the spine should already be clear. Of course, there are a huge number of small details and features, but one article to reveal all the subtleties is simply not enough.