THE SPINAL RESEARCH FOUNDATION Improving spinal health care through research, education, and patient advocacy

Your spine has many important jobs. It gives your body structure and support, allows you to stand up and keep yourself upright, move about freely and bend with flexibility. Its natural curves absorb and distribute forces placed upon it.  The spine is also designed to protect your spinal cord. The spinal cord is a column of nerves that connects your brain to the rest of your body, allowing you to control your movements. Without a spinal cord you could not move any part of your body, and your organs could not function. Keeping your spine healthy is vital if you want to live an active life.

 

Vertebrae

The spine is made up of 24 moving vertebrae. Ligaments and muscles connect these bones together to form the spinal column. The spinal column gives the body form and function and protects the spinal cord.  The many muscles that connect to the spine help support the upright posture of the spine and move the spine.

The spinal column has three main sections:

  • The first seven vertebrae form the cervical spine.  These vertebrae provide more rotational movement than the other sections.
  • The mid back, called the thoracic spine, consists of 12 vertebrae.  These vertebrae are more limited in motion due to their attachment to the ribs.
  • The lower portion of the spine, called the lumbar spine, is usually made up of five vertebrae, although some people have a sixth lumbar vertebra.  These are the most weight-bearing vertebrae.

The normal spine has an "S"-like curve when looking at it from the side. This allows for an even distribution of weight. The "S" curve helps a healthy spine withstand all kinds of stress. The cervical spine curves slightly inward, the thoracic slightly outward, and the lumbar slightly inward. Even though the lower portion of your spine holds most of the body's weight, each segment relies upon the strength of the others to function properly.

Discs

The discs in between each vertebrae consist of two main parts:

  • Annulus – outer concentric rings of cartilage, like a radial tire.
  • Nucleus – gel-like pulp inside the annulus, starts at 88% water when born, but dries with age.

Each disc is firmly attached to the two vertebrae to which it is linked.  These “shock absorbers” are thicker in the weight-bearing lumbar area.

Movement and pressure can cause the outer cartilaginous rings to tear, and eventually the nucleus may bulge out.  This is called a disc bulge, or herniation.

Joints/Facets

The facet joints are on the back of the spine on each side, where one vertebrae slightly overlaps the adjacent vertebrae.  Their purpose is to guide and restrict movement of the spine.  Lifting incorrectly can irritate the facet joints.

Foramen/Nerve Roots

Foramen are canals between adjacent vertebra that are formed by the overlapping of the facet joints.  Nerve roots exit from the spinal cord through these canals.

Spinal movements affect the size of the foramen; a narrowing is called stenosis.