A bulging disk is an intervertebral disk that is extending beyond its normal boundary.
A buldging disk causes pain if it bulges onto a nerve. (The spinal cord is all nerve tissue.) This will depend upon how far it is bulging and in which direction.
Bulging and herniated disks cause pain because the soft material flows out, usually onto nerves. The nerves respond by sending pain signals. The bulging disk is not always painful.
