Vertebral canal

Recommended video: Cavities of the body [25:33]

Learn here the cavities of the human body.

The vertebral canal, also called the spinal canal or vertebral cavity, is one of two subdivisions of the dorsal body cavity, the other being the cranial cavity. It is a channel within the articulated vertebral column (spine), formed by the stacked vertebral foramina of the vertebrae. It extends from the foramen magnum of the skull proximally, to the sacral hiatus distally. 

It contains and protects the spinal cord, which occupies the upper two thirds of the canal, as well as the roots of spinal nerves, associated meninges and blood vessels that supply these structures. A layer of adipose tissue within the canal separates the meninges from the surrounding bone.

The vertebral canal varies in size and shape depending on the region of the spine to accommodate the varying width of the spinal cord. It is bordered anteriorly by the posterior aspect of the vertebral bodies of vertebrae and intervertebral discs, which are lined by the posterior longitudinal ligament. The lateral walls of the canal are formed by the pedicles of each vertebral arch and openings called the intervertebral foramina which transmit the spinal nerves. Posteriorly, the canal wall is formed by the laminae and the ligamentum flava between adjacent laminae.

The vertebral canal tapers distally becoming narrower and continuing through the sacrum as the sacral canal which contains the cauda equina. It ultimately terminates at the sacral hiatus, an inferior opening where the laminae of the last sacral vertebra remains unfused.