Anatomy

The adult spine is a column of 33 bones that protects the spinal cord and enables us to stand upright. Each bony segment of the spine is referred to as a vertebra (two or more are called vertebrae).

The spine has five regions containing groups of similar bones, listed from top to bottom: 7 cervical vertebrae in the neck, 12 thoracic vertebrae in the mid-back (each attached to a rib), 5 lumbar vertebrae in the lower back, 5 sacral vertebrae fused together to form one bone in the hip region, and 4 coccygeal bones fused together that form our tailbone.

At the front of each vertebra is a block of bone called the vertebral body. The vertebral body consists of an inner core of soft cancellous bone, surrounded by a thin outer layer of hard cortical bone. Vertebrae are stacked on top of each other and enable us to sit/stand upright.

Vertebrae in the the cervical, thoracic and lumbar regions are separated from each other and cushioned by a rubbery soft tissue called the intervertebral disc. Segments of bone that extend outward at the back of each cervical, thoracic and lumbar vertebral body surround and protect the spinal cord and its nerve roots. You can feel these bones, known as the posterior spinous processes, when you run your hand along the middle of your back.

The vertebral bodies in the thoracic and lumbar regions have the greatest risk for fracture due to osteoporosis. Cancer and benign tumors can lead to fracture of the cervical, thoracic and lumbar vertebrae.

Normal vertebra (side view)

Fractured vertebra (side view)