If you ever had a painful cracked tooth, you know it when you bite down with some force.

cracked disc - vertebraeIt hurts. And if you are wondering why I am opening with the discussion of a cracked tooth on this chiropractic blog, well, it is because it resembles the problems found in the spine….a cracked disc.   Inside the intervertebral disc of the spine houses some of the toughest ligaments in the body and these ligaments are called the annulus fibrosus. Cracks develop in these tissues very similar to the cracks found in a tooth. As excessive or abnormal forces are placed on these tissues, cracks develop from the inside of the disc. Just as in a tooth, if the crack is small, you don’t feel it. But if the crack is large enough and it is the vicinity of a nerve, pain presents itself awfully quick. This is very similar to the spine as radial tears crack (in a radius-like fashion) from the inside out.

cracked disc - radial tear

Above is a top down view of an intervertebral disc. The radial tear is the outward red crack seen. This is the beginning of a degenerated disc. Often when people “throw their back out”, they have experienced a new radial tear. Some people will experience pain and some others do not. This has always intrigued clinicians but I believe it is as simple as whether or not the tissue is innervated.   Research has moved us towards better understanding of the nerves in the disc. Originally it was thought the intervertebral disc was void of nerves but we know now that the outer third of the annulus is innervated. When cracks (AKA radial tears) develop, new nerves actually begin to grow into the damaged tissues that never had nerves to begin with! These nerves that innervate the outer third (and inner two thirds if damaged) of the annulus fibrous are branches from a larger nerve names the sinuvertebral nerve.

cracked disc - L4

So if you are wondering what it means to “throw your back out”, it is in part, very likely, that a new tear may have developed and it has cracked in to an area where a nerve is. Common findings are stiffness in the morning as these cracks spread after a night of increasing intervertebral pressures.   Chiropractors often treat radial tears whether they know it or not. Some respond and some don’t. Often it requires careful coupling of safe exercises to allow them to heal.