Schmorl’s nodes are vertebral lesions. The term technically refers to the prolapsed intervertebral disc material that enters the vertebral body either superiorly or inferiorly to the disc but it has since come to be used to refer to the lesion which forms as a result. The process begins when there is an extrusion of the nucleus pulpous material, which travels through a fissure in the cartilaginous endplate and erodes the vertebral body. This degenerates the trabecular bone and results in cavities in the surface of the vertebrae (Faccia and Williams 2008:29-30). At present, research suggests that Schmorl’s nodes occur due to congenital defects such as Scheurmanns kyphosis that results in a series of nodes throughout the spine, traumatic events or senescent processes. If trauma is involved high axial loading, and fractures of the cartilaginous endplate are possibilities that may cause lesions as they deform and rupture the intervertebral disc. Schmorl’s nodes are often found in the lower thoracic and lumbar vertebrae, which are commonly attributed to the biomechanics of the lower spine, loading and on posture. However, there is current uncertainty amongst medical practitioners as to whether Schmorl’s nodes cause pain or not. Recent studies show that nerves enter the vertebrae via basivertebral foramen apertures in the anterior cortex. The basivertebral nerves have tested positive as being painful to stimuli, and are thought to be part of the sympathetic nervous system.
See Faccia and Williams. 2008. “Schmorl’s nodes: clinical significance and implications for the bioarchaeological record” in International Journal of Osteoarchaeology 18 (1): 28–44