The anatomy of the lumbar intervertebral disc syndrome.

Four elements of the nervous system may be involved in the production of the lumbar intervertebral disc syndrome. These are the lumbosacral nerve roots, the spinal nerves, the dorsal rami and the sinuvertebral nerves. Each nerve is associated with a particular group of pathological conditions which may irritate the nerve and produce symptoms. The anatomy of each nerve determines which particular conditions may irritate it. Moreover, one or both of two mechanisms may be involved in symptom production. The type of nerve irritated determines which mechanism is involved. In the first mechanism, low back pain and referred lower limb symptoms are produced when afferent fibres from dorsal and ventral rami are stimulated where they pass in common through spinal nerves or nerve roots. In the second mechanism, dorsal rami or sinuvertebral nerves are stimulated. This directly produces low back pain, but referred pain is produced by reflex mechanisms in the spinal cord.