Spinal Stenosis is narrowing of the spinal canal. The black ring represents the spinal canal and the blue arrows the changes which narrow the canal. The spinal canal has a floor (vertebra, discs), a roof (lamina, ligament), and side walls (facets, pedicles). Stenosis is represented by the remaining space in the center of the black ring bounded by the blue arrows.



Schematic representation of the spinal canal (blue triangle): note the position of the spinal cord (green circles) in the triangle. The spinal canal (blue triangle) can be effected by changes on its borders (black circle, yellow arrows, red facet joints). This drawing represents one ring.