Spine Regions: Structure, Numbering, and Functions

The spine is the load-bearing structure of the body: it bears weight, protects the spinal cord, and works as a system of levers and hinges. An MRI report or a doctor's note is read by levels — C5, L4. Below is the structure of the column by region.

What regions the spine consists of

In humans, the spinal column consists of 32–33 vertebrae connected in sequence to one another in a vertical position. Anatomists distinguish five regions: cervical, thoracic, lumbar, sacral, and coccygeal (caudal). The column has three tasks: support, protection of the spinal cord, and participation in movements of the trunk and head.

• cervical — 7 vertebrae;
• thoracic — its vertebrae bear the ribs, which are connected to the sternum;
• lumbar — the lower part of the back, where pain occurs very often;
• sacral — the region following the lumbar;
• coccygeal (caudal) — the last region of the column.

Cervical region: vertebrae C1–C7

In mammals, the cervical region contains a constant number of vertebrae — 7. The first and second cervical vertebrae differ in structure from the others: all the rest share a common structural plan. An example of a level entry is “C5–C6”.

Thoracic region of the spine

The ribs, which are connected to the sternum, articulate with the anterior thoracic vertebrae — together they form the rib cage. A landmark on the body is the scapulae: pain in the upper part of the back, between the shoulder blades, is a reason to consult a doctor.

Lumbar, sacral, and coccygeal regions

The lumbar, sacral, and coccygeal regions come last. Pain in the lower part of the back usually resolves within a few weeks.

Numbering of vertebrae and structure of a vertebra

Levels in a report are designated by the letter of the region and the number of the vertebra. A vertebra, except for the first two cervical ones, consists of a body facing forward and bearing a supporting function, and an arch connected to the body by pedicles. Between them is the vertebral foramen; all the foramina together form the spinal canal, in which the spinal cord lies. The spinous, transverse, and articular processes extend from the arch: the vertebrae articulate with one another by them, and muscles attach to them.

Intervertebral discs and nerves of the back

Between the vertebral bodies lie cartilaginous layers — the intervertebral discs. They act as shock absorbers and provide mobility of the column. A disc is named after the adjacent vertebrae, which is why an entry such as L4–L5 appears in a report. The spinal cord and the nerves arising from it pass inside the canal; with a disc herniation, stenosis, and age-related bone changes, pressure on the cord and nerves causes pain and limits movement. Among the examinations used are MRI and CT of the spine, electromyography and nerve conduction studies, and discography. A doctor is consulted if pain does not resolve within a few weeks, interferes with usual activities, does not resolve after rest, or intensifies at night and with coughing, sneezing, or defecation, as well as with weight loss, swelling, or a change in the shape of the back.

Seek medical attention immediately: back pain by itself is not a reason to call an ambulance; 103 or 112 are needed if there is at least one sign — pain, tingling, weakness, or numbness in both legs; loss of sensation around the genital organs and anus; changes in urination or bowel movements, including incontinence; changes in sensation during sexual intercourse or inability to achieve an erection; chest pain; the pain began after a serious accident.

This material is for reference: it explains the structure of the column but does not replace consultation with a doctor — only a specialist can correlate the complaints, examination, and imaging findings.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer