Anatomy of the spine

The best way to prevent diseases of the spine is to know its anatomy and prevent physical overload and injuries of the spinal column.

Several sections are distinguished in the human spine, depending on localization:

  • cervical spine - consists of 7 cervical vertebrae, very mobile, especially in its lower segments (C5-C6-C7)
  • thoracic region - formed from 12 thoracic vertebrae
  • the lumbar spine is represented by 5 lumbar vertebrae with the most mobile lower segments (L4 – L5 – S1)
  • the sacrum is a monolith of 5 sacral vertebrae fused into a single sacral bone
  • the tailbone consists of 2-5 vertebrae and can be mobile in women, which is associated with their reproductive function

The human spine consists of 7 cervical, 12 thoracics, 5 lumbar vertebrae, fused into one block of the sacrum vertebrae and the coccyx articulated to it.

The anatomy of the spine is a complex structure that can be divided into two parts.

The anterior part of the spine consists of cylindrical vertebral bodies. Each vertebra is connected to an adjacent vertebra by an intervertebral disc. The exceptions are the connections between the C1 and C2 vertebrae, as well as the fused vertebrae of the sacrum and coccyx. The vertebral bodies are held together by the anterior and posterior longitudinal ligaments that cover them from the front to the back.

The anterior longitudinal ligament is tightly adhered to the intervertebral disc and vertebral bodies, while the posterior longitudinal ligament is not so strong concerning these structures. This weakness leads to prolapse or squeezing of the contents of the disc (hernia, protrusion) exclusively in the posterior direction towards the lumen of the spinal canal, causing compression of the spinal cord located there and the nerve roots extending from it.

Spine anatomy: cervical, thoracic and lumbar vertebrae (back view).

The back of the vertebrae is formed by bony structures that extend from the vertebral body in the form of legs and expand backward to form the vertebral arch. Together with the posterior longitudinal and yellow ligaments, the arch of the vertebra forms the vertebral canal, in which the spinal cord and its roots are located. The posterior parts of the vertebra are articulated with the adjacent vertebrae by two small intervertebral (facet) joints. The intervertebral (facet) joints have a small articular surface, most pronounced in the lumbar spine. These articular areas provide certain mobility of the spine.

The vertebrae posteriorly have strong transverse and spinous bony processes. The transverse processes extend laterally from the vertebral pedicles. The spinous processes run in the posterior direction. Attached to these processes are ligaments and tendons of the back muscles, which set in motion, support, and protect the spinal column.

Vertebral anatomy: vertebral body, arch of the vertebra, articular processes of the vertebra, transverse processes of the vertebra, spinous process of the vertebra, intervertebral disc (nucleus pulposus and annulus fibrosus).

The center of the intervertebral disc is occupied by the gelatinous nucleus pulposus, which is considered the remnant of embryonic tissue (chord). It is surrounded and supported by a fibrous ring, consisting of fibrous-cartilaginous and connective tissue.

After the completion of the development of the spine (at the age of 24–26 years), the intervertebral discs lose their blood supply vessels. In the future, the intervertebral discs become less elastic and less efficiently cope with the role of shock absorbers when walking. These changes can lead to disorders in the most mobile parts of the spine: in its cervical and lumbar segments.

Spine anatomy: spinal cord, vertebrae, intervertebral disc.

The following structures give stability to the human spine:

  • articulations of the vertebral bodies through the intervertebral discs and intervertebral joints
  • ligaments and muscles of the spine

The ligamentous apparatus of the spine has sufficient strength to displacement. The vertebral bodies with the intervertebral disc do not have the same overall strength as the ligaments to withstand displacement under the loads acting on the spinal column during movements. This weakness of the spine is compensated for by the voluntary and reflex contractions of the sacro-vertebral, abdominal, gluteal, and square muscles of the lower back, as well as the hamstring, which provides such stability.

The spinal cord is located in the lumen of the spinal canal. In a child, he fills it almost completely. With the growth of a person, already in adulthood, the cone of the spinal cord reaches only the level of the 1st or 2nd lumbar vertebra, because the nervous tissue does not keep pace with the rapid growth of the bones of the skeleton.

Spine anatomy: lumbar vertebrae, spinal cord and cauda equina, sciatic nerve.

The structures of the spine are innervated from the recurrent branches of the spinal nerves. Painful endings and fibers of this nerve were found in the ligaments, muscles, periosteum of the processes, the outer layers of the fibrous ring of the intervertebral disc, and in the synovium of the intervertebral (facet) joints. Sensory fibers from these structures of the spine and the sacroiliac and lumbosacral joints, joining, form the Luschke's synvertebral nerves, which enter the recurrent branches of the spinal nerves at the S1 and L1-L5 levels in the gray matter of the corresponding segments of the spinal cord. Motor fibers emerge from these segments and reach muscles as part of the same nerves.

The location of the spinal cord in the spinal canal.

The lumbar and cervical spine have the greatest freedom of movement. In comparison with them, the thoracic spine is reliably and firmly fixed by the bones of the chest. Greater mobility of the neck and lower back is the reason for his frequent damage. In addition to voluntary movements that provide flexion and twists of the trunk, many movements of the spine are reflex and ensure the maintenance of the body's position in space, as it happens when walking or running.

The structure of the spine and spinal cord, cross-sectional view.

Epidural fatty tissue surrounds the lining of the spinal cord. Infection of the epidural tissue leads to purulent spinal epiduritis.


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