Vertebrae

Spine Anatomy:

Vertebrae

Although the vertebrae have slightly different appearances as they range from the cervical spine to the lumbar spine, they all have the same basic structures, and the structures have the same names. Only the first and second cervical vertebrae are structurally different in order to support the skull.

Each vertebra has an anterior arch and a posterior arch, which form a hole, called a foramen. The spinal cord passes through foramen of each vertebra.

The anterior arch is called the vertebral body. Discs connect one vertebral body to another to allow motion of the spine and cushion it against heavy loads. Together, the vertebral bodies and discs bear about 80 percent of the load to the spine.

The posterior arch consists of the pedicles, laminae, and processes.

The pedicles are two short cylinders of bone that extend from the vertebral body. Nerve roots branch off the spinal cord and exit to the body between the pedicles of two vertebrae. If the spine becomes unstable, the pedicles may compress the nerve root, cause pain or numbness.

Laminae are two flattened plates of bone that form the walls of the posterior arch. Over time, the laminae may thicken, a process called stenosis. This thickening compresses the spinal cord and/or nerves causing pain or numbness.

The articular, transverse, and spinous processes project off the laminae. Ligaments and tendons attach to the processes. The articular processes join one vertebra to another posteriorly.

The transverse processes extend out on either side of the laminae. The spinous process is the bony projection that can be felt through the back of someone’s skin.