INNERVATION OF THE RABBIT LUMBAR INTERVERTEBRAL DISC AND POSTERIOR LONGITUDINAL LIGAMENT

Study Design. The present study sought to determine to what extent the lumbar intervertebral disc and posterior longitudinal ligament are in nervated in the New Zealand white rabbit. The intent is to use this di sc model in future neurophysiology studies. Objective. To characterize the distribution of nerve fibers and endings in the lumbar interverte bral disc and posterior longitudinal ligament in an animal model. Summ ary of Background Data. The results of previous disc innervation repor ts are somewhat conflicting regarding the density and depth of innerva tion into the anulus. Methods. A silver impregnation technique was use d to analyze sections from lumbar intervertebral disc and posterior lo ngitudinal ligament of the New Zealand white rabbit, Results. Numerous fine profiles of nerve fibers were demonstrated in the lumbar disc an ulus and posterior longitudinal ligament. In the disc, the nerves were limited to the superficial anulus and anular surface. The nerve axons typically were 1 to 3 mu m in diameter and were found around the enti re periphery of the disc. No encapsulated endings were seen within the anulus, while occasional encapsulated endings were seen on the anular surface and posterior longitudinal ligament. Conclusion. This study d emonstrates an extensive distribution of small nerve fibers in the siz e range of C and A-delta fibers throughout the peripheral anulus and p rovides an illustration of this distribution. These findings support a role for the disc as a source of low back pain.