Objective To investigate the distribution of sensory nerve terminals in the lumbar intervertebral disc and posterior longitudinal ligament (PLL) in an animal model. Methods Immunohistochemical method was used to visualize nerve terminals with antibodies of substance P(SP) and calcitonin gene-related peptide(CGRP), and to characterize sensory nerve terminals on sections from lumbar intervertebral disc and posterior longitudinal ligament(PLL) of the Sprague Dawley rats.Results The immunostaining revealed an extensive distribution of SP and CGRP immunoreactive nerve fibers in the surface and most superficial portions of all annulus fibrosus and PLL. Most immunoreactions were observed in ventral and lateral regions of the annulus fibrosus. Morphologically, both thin varicose nerve fibers and tiny punctate nerve terminals could be observed. Conclusion This study demonstrates an extensive distribution of SP and CGRP immunoreactive nerve fibers throughout the PLL and the peripheral annulus fibrosus and provides an illustration of this distribution. This finding supports a role for the disc as a source of low back pain and provides the neuroanatomic foundation of the disc-genic pain. Objective To investigate the distribution of sensory nerve terminals in the lumbar intervertebral disc and posterior longitudinal ligament (PLL) in an animal model. Methods Immunohistochemical method was used to visualize nerve terminals with antibodies of substance P (SP) and calcitonin gene-related peptide ( CGRP), and to characterize sensory nerve terminals on sections from lumbar intervertebral disc and posterior longitudinal ligament (PLL) of the Sprague Dawley rats. Results The immunostaining revealed an extensive distribution of SP and CGRP immunoreactive nerve fibers in the surface and most superficial portions of all annulus fibrosus and PLL. Most immunoreactions were observed in ventral and lateral regions of the annulus fibrosus. Morphologically, both thin varicose nerve fibers and tiny punctate nerve terminals could be observed. Conclusion This study demonstrates an extensive distribution of SP and CGRP immunoreactive nerve fibers throughout the PLL and the peripheral annulu s fibrosus and provides an illustration of this distribution. This finding supports a role for the disc as a source of low back pain and provides the neuroanatomic foundation of the disc-genic pain.