Facet joints are synovial joints which help to support the weight and control movement between individual vertebrae of the spine. They are sections of the spine where the vertebrae connects to one another. The facet joints work together alongside the discs to form a working back.
They have a nerve supply for two levels, one from the nerve root and another from the level above.
Back pain due to facet joints is due to a spasm of adjacent muscles. You could have just sneezed or bent to pick up something from the floor and your back just gets stuck. They call this facet joint syndrome which is usually treated without surgery through Physiotherapy, Exercise, Drugs, Stretching, and injections.
It is present in 40% of the elderly population and the term means 'low back pain that comes from the facet joints of the spine'. Causes of facet joint degeneration can be from osteoarthritis, degenerative disc disease, and excessive use of the spine.