Disc herniations can cause pain, numbness, and weakness. Nerve roots emerge from the spinal cord and exit the spine through the openings between the discs and the joints, one on the left and one on the right, at every spinal level. When nuclear material extrudes through the annulus into the lateral recesses, it can come into contact with one or more of the nerve roots, compressing or simply irritating them. Nerve root compression or irritation is called radiculopathy, or what is often referred to as a ‘pinched nerve.’
Nerves which emerge from the neck run down the arms to the hands and fingers; nerves which emerge from the lower back run down the legs to the feet and toes. Each nerve carries electrical impulses down to stimulate muscles to contract, and also carries impulses back from the skin and body tissues which is how we perceive sensation. Each different nerve supplies its own specific set of muscles and its own specific patch of skin, and these are quite consistent from person to person. For example, radiculopathy of the C-6 nerve, caused by a herniated disc at C5/6, can cause pain and/or numbness and/or tingling in the upper back, shoulder, arm, hand, thumb and first finger; it can also cause weakness in the muscles which bend the elbow (biceps) and pull the wrist backward (wrist extensors). On the other hand, a herniated disc at C5/6, in which the extruded nuclear material does not compress or irritate a nerve may very likely cause no symptoms whatsoever, and most people have experienced at least one such disc herniation somewhere in their spine over the course of their lifetime without knowing it.