The vertebral column is the central support structure of the body. It is formed by individual bones, called vertebrae, stacked from the base of the skull down to the pelvis. Its primary purpose is to provide structural support for the head and torso while protecting the delicate spinal cord. The column is divided into five distinct regions, each arranged in a precise anatomical order from top to bottom.
The Cervical and Thoracic Regions
The sequence begins at the skull with the Cervical region (C1 through C7). These seven small vertebrae are the smallest and most mobile of the entire column, allowing for a wide range of motion. The first two vertebrae, C1 (Atlas) and C2 (Axis), have unique shapes to facilitate head movement. The ring-shaped C1 supports the skull and pivots around a bony projection on C2, allowing for head rotation.
The Thoracic region comprises the 12 vertebrae of the mid-back, numbered T1 through T12. This region is distinguished by its direct connection to the rib cage, as each thoracic vertebra articulates with a pair of ribs. This attachment provides stability and protection for the internal organs within the chest cavity. The presence of the ribs and joint orientation significantly limit the spine’s flexibility compared to the cervical region.
The Lumbar, Sacral, and Coccygeal Regions
The downward progression continues into the Lumbar region, which forms the lower back. This segment contains five large vertebrae (L1 through L5), which are the largest individual bones in the movable spine. Their size and thicker structure reflect their primary function of bearing the majority of the body’s weight and handling mechanical stresses. The lumbar spine allows for significant forward and backward bending, though it is less flexible in rotation than the cervical area.
Inferior to the lumbar spine is the Sacral region, a single triangular bone called the sacrum, situated between the two hip bones. It is formed by five separate sacral vertebrae (S1–S5) fusing together during late adolescence or early adulthood. The sacrum forms a strong connection between the spine and the pelvis, transmitting the body’s weight to the lower limbs.
The final segment of the vertebral column is the Coccygeal region, or coccyx, commonly known as the tailbone. Positioned at the inferior terminus of the spine, the coccyx is typically formed by the fusion of three to five very small, rudimentary vertebrae. Although small, this bone serves as an attachment point for various ligaments and muscles of the pelvic floor.