Normal Anatomy of the Spine

Normal Anatomy of the Spine

The spine, also called the backbone, is designed to give us stability, smooth movement as well as provide a corridor of protection for the delicate spinal cord. It is made up of bony segments called vertebrae and fibrous tissue called intervertebral discs. The vertebrae and discs form a column from your head to your pelvis, giving symmetry and support to the body.

The spine can be divided into 4 parts. The uppermost is the cervical region, consisting of 7 small vertebrae that form the neck. As we move down the body, the next 12 vertebrae make up the thoracic region or mid back, from which the ribs are hinged. The 5 lumbar vertebrae are the largest of the mobile vertebrae and support 2/3 rd of the body's weight.

The lowest region of the spine is the sacrum and coccyx. The sacrum is a triangular plate made up of five fused vertebral segments, while the four coccyx bones terminate the bony spine.

Vertebrae

A single vertebra is made up of two parts, the front portion is called the body, which is cylindrical in shape, and is strong and stable. The back portion of the vertebra is referred to as the vertebral or neural arch and is made up of many parts. The 2 strong pedicles join the vertebral arch to the front body. The laminae form the arch while the transverse processes spread out from the sides of the pedicles like wings to help anchor the vertebral arch to the surrounding muscles. The spinous process forms a steeple at the apex of the laminae and is the part of our spine that is felt directly under the skin. The laminae of the vertebra can be described as a pair of flat-arched bones that form a component of the vertebral arch.

The spinal canal is formed by the vertebral foramina of each vertebra, stacked one on top of the other to form a canal. The canal creates a bony casing from the head to the lower back, through which the spinal cord passes. Pars inter articularis, known as the Pars, is the part of the vertebral arch where the pedicle, transverse process and articular process transect.

Facet joint

Facet joints are paired articular processes of the vertebral arch. These synovial joints give the spine its flexibility by sliding on the articular processes of the vertebra below.

Fibrous tissue

The intervertebral disc sits between the weight-bearing vertebral bodies, serving as shock absorbers. The disc has a fibrous outer ring called the annulus fibrosus with a watery jelly-filled nucleus called the nucleus pulposus.

Spinal cord

The spinal cord consists of nerves that communicate through electrical signals between the brain and the body. It begins at the brain stem and runs through the spinal canal across the entire length of the vertebral column.