Intervertebral Disc: An intervertebral disc is a fibrocartilaginous structure found between the bodies of vertebra. These discs are located between each pair of vertebra in the lumbar spine. Think of this disc as being similar to a jelly doughnut: there are a series of outer fibrous rings that surround a softer center. The outer annular rings are thinnest posterior and lateral; most disc bulges occur at this location due to the weakness of the disc wall. The disc functions as a cushion, allows for movement, and serves as a cartilaginous joint between adjacent vertebrae. What is a Bulging Disc? A bulging disc occurs when the outer walls of the intervertebral disc become weak, and the interior gelatinous substance pushes the wall out past its normal perimeter. It is possible to have a bulging disc without knowing it if it does not press on any of the nearby structures in the spine. However, if the bulge does put pressure on the nerves, ligaments or surrounding tissues symptoms can occur. The majority of bulging discs occur in the lumbar spine, at levels L4-L5 and L5-S1. A bulge in the lumbar spine can affect the sciatic nerve, creating a condition called sciatica.