Anatomy


The cervical spine is made up of the first seven vertebrae in the spine. It starts just below the skull and ends at the top of the thoracic spine. The cervical spine has a backward "C" shape (lordotic curve) and is much more mobile than either of the thoracic or lumbar regions of the spine. Unlike the other regions of the spine, the cervical spine has special openings in each vertebrae for the arteries that carry blood to the brain.

The first two vertebral bodies in the cervical spine are called the atlas and the axis. The atlas is named after a mythical Greek god who supported the weight of the world on his shoulders, because this is the vertebral body that supports the weight of you head. The atlas and axis vertebrae in the cervical spine differ from all other vertebrae because they are designed primarily for rotation. The atlas has a thick forward (anterior) arch and a thin back (posterior) arch, with two prominent masses.

The axis sits underneath the atlas and has a bony knob called the odontoid process that sticks up through the hole in the atlas. It is this mechanism that allows the head to turn from side to side. There are special ligaments between these two vertebrae to allow for rotation between these two bones.

Between each vertebra in the cervical spine are discs which act as cushions or shock absorbers and also permit some movement between the vertebral bodies. The entire spinal column is joined together by ligaments that allow the spine to bend and twist carrying the weight of the human body with just the right balance of strength and flexibility. In addition to the invertebral discs, special joints between each of the vertebral bodies, called facet joints, allow the individual bones of the spine to move and rotate with respect to each other. These joints are important because they can be a source of pain if they become arthritic. Many muscle groups, that move the trunk and the limbs, also attach to the spinal column. The muscles, that closely surround the bones of the spine, are important for maintaining posture and helping the spine to carry the loads created during normal activities, work, and play. Strengthening these muscles can be an important part of physicial therapy and rehabilitation.

Each vertebra is shaped in a special way so that when they are stacked together, the spinal cord is protected from damage by the bones of the entire spinal column. The spinal cord is part of your central nervous system and is a direct extension of your brain. It is made up of a large collection of nerves and carries messages from your brain to the rest of your body.

Vertebrae

The vertebrae support the majority of the weight imposed on the spine. The body of each vertebra is attached to a bony ring that consists of several parts. A bony projection on either side of the vertebral body called the pedicle supports the arch that protects the spinal canal. The laminae are the parts of the vertebrae that form the back of the bony arch, that surrounds and covers the spinal canal. There is a transverse process on either side of the arch where some of the muscles of the spinal column attach to the vertebrae. The spinous process is the bony portion of the vertebral body that can be felt as a series of bumps in the center of a person's neck and back.

Intervertebral Disc

The discs located in between each vertebrae function as shock absorbers and as joints.They are designed to absorb the stresses carried by the spine while allowing the vertebral bodies to move with respect to each other. They made up of a strong outer ring of fibers called the annulus fibrosis, and a soft center called the nucleus pulposus. The outer layer (annulus) helps keep the disc's inner layer intact. The annulus is made up of very strong fibers that connect each vertebrae together. The nucleus of the disc has a very high water content making it very moist.

Facet Joint

The facets connect the bony arches of each of the vertebral bodies. There are two facet joints between each between each pair of vertebrae one on each side. Facet joints connect each vertebra with the next vertebra above and below. They are primarily designed to allow the vertebral bodies to rotate with respect to each other.


Neural Foramen

The neural foramen is the opening where the nerve roots exit the spine and travel to the rest of the body. There are two neural foramen located between each pair of vertebrae, one on each side. The foramen creates a protective passageway for the nerves that carry signals between the spinal cord and the rest of the body.

Spinal Cord and Nerve Roots

The spinal cord extends from the base of the brain to the area between the bottom of your first lumbar vertebra and the top of your second lumbar vertebra. The spinal cord ends by dividing into individual nerves that travel out to your lower body and your legs. This group of nerves at the end of the spinal cord is called the cauda equina, which is the Latin name for a horse's tail. For a short distance the nerve groups travel through the spinal canal before they exit out the neural foramen.

The dura mater is the protective membrane that covers the spinal cord. The dura mater forms a watertight sack around the spinal cord and nerves. The spinal cord is surrounded by spinal fluid inside this sack.

The nerves in each area of the spinal cord connect to specific parts of the body. The nerves of the cervical spine go to the upper chest and arms. The nerves also carry electrical signals back to the brain creating sensations. Damage to the nerves, nerve roots, or spinal cord can lead to symptoms such as pain, tingling, numbness and weakness.

The materials on this Web site are for your general educational information only. Information you read on this Web site cannot replace the relationship that you have with your health care professional. We do not practice medicine or provide medical services or advice as a part of this Web site. You should always talk to your health care professional for diagnosis and treatment.

Published: April 30, 2007
Updated: February 12, 2008