Dermatomes are areas of skin (derma) that a single nerve from the spinal column is associated with. Nerves come out from the spinal column and innervate our arms and legs. They connect to our muscles like brain powered extension cords. Why should you know about them? They act like a map, and can help determine the source of a spinal issue. Ever have a shooting pain somewhere in your body? A pinched nerve? Most of the time, those pains may be signals stemming from an issue within the spine, whether it is stenosis, bone spur, disk herniation, or bulge. It’s not a perfect science: sometimes the muscles that nerves run through can also be the source of a nerve pinch.