Overview of the Spine
Anatomy and Function
Understanding the fundamental anatomy and function of the spine is key to understanding injuries and diseases of the spine. The spine has several special roles in the human body:
- Protects the spinal cord
- Provides the support needed to walk upright
- Enables the torso to bend
- Supports the head
Sections of the Spine
Cervical – commonly referred to as the neck. There are seven cervical vertebrae (doughnut-shaped bones) that connect the skull to the rest of the spine.
Thoracic – The spine’s thoracic section begins at the shoulders and extends down to the end of the rib cage. There are 12 vertebrae in the upper back, with shock-absorbing discs between them. Scoliosis commonly affects the thoracic section of the spine.
Lumbar – The lumbar section, or low back, has five vertebrae. These vertebrae, separated by discs, are the largest in the spine. Degeneration most often occurs in the lumbar section, usually at the lower discs. In addition, the facet joints can become arthritic, causing pain.
Sacrum – Five vertebrae join together to form the sacrum, a wedge-shaped part of the spine that forms part of the pelvis. The sacrum joins the rest of the pelvic bone at the sacroiliac joint, which can become inflamed causing sacroiliitis.
Coccyx – often referred to as the tailbone, consists of four vertebrae.
Vertebrae – The spine has 33 doughnut-shaped bones called vertebrae. Each vertebra is assigned a letter and a number that identifies its location in the spine. When someone has osteoporosis, minor trauma can cause these bones to fracture.
Discs – Between each pair of vertebrae is a disc made of spongy cartilage. Intervertebral discs act as shock-absorbing cushions between the vertebrae. When the disc degenerates, it can be pushed posteriorly, causing disc herniation.