To Understand Back Pain You May Need an Anatomy Lesson
When a patient asks,”Why does my back hurt?” the answer can take a bit of detective work. Dr. Christopher Winfree from the Neurosurgical Pain Center says that the exact cause is often elusive, but there are six anatomical structures in the spine that are the most common sources of low back pain. He outlined each along with some treatment options in a presentation given at a meeting of the American Association of Neurological Surgeons.
The spine is made up of bones called vertebrae that stack on top of each other from head to tail. There is a hole in the center of each vertebra that, when stacked, forms a bony tube that houses the spinal cord.
The space inside this tube around the cord is called the epidural space, and it contains blood vessels, nerves and lymphatics. Dr. Winfree says, “This space may be the site of compression, inflammation, and or scarring” and the treatment can include a steroid injection (to decrease the inflammation) or surgery to remove the scarring.
There are two nerve roots inside the epidural space, each formed by a branch coming off the front and back of the spinal cord. The nerve roots come out of the spine through bony holes on the sides of each vertebra, sending out nerves to our arms and legs. The nerve roots themselves, says Dr. Winfree, “may be subjected to compression or inflammation that typically results in pain down the leg.” Doctors can inject either a steroid or pain reliever near the nerve root but sometimes surgery is necessary to remove whatever is compressing it.
In the back of the spine, where the bottom of one vertebra meets the top of another, are two facet joints. These joints get their feeling from nerves that come right off of the spinal cord and are “thought to be the pain generator in about a third of low back pain cases,” says Dr. Winfree. The simplest and least complicated neurosurgical treatment is an injection at the joint, but the nerve to the joint is sometimes cut to completely eliminate the pain.
At the bottom of the spine, the vertebrae widen and fuse together forming the Sacrum. The Sacrum sits right above the tail bone and is connected to the pelvis on each side forming what are called the Sacroiliac joints. Dr. Winfree says that though these joints don’t move much, they have a lot of sensory nerves and, “inflammatory and degenerative processes may be quite painful here.” In the early 1900’s this joint made up the bulk of back pain diagnoses. Today it is thought to be the cause in about one sixth of cases. As with the other structures, it can be relieved by injection.
Sitting between each vertebra is a pad called the intervertebral disc. With an outer layer of cartilage and an inner more jelly-like center. It is a great shock absorber but, it is also the cause of about a third of all low back pain. A number of problems can arise from this disc including degeneration, tears, bulging, collapse or herniation. Any of which can cause terrible low back and/or leg pain. One treatment for the disc involves inserting a coil and heating it up from the inside. This effectively shuts off feeling in the disc so there is no more pain.
The rounded block-like bone at the front of the vertebra is called the vertebral body and the main concern with this part of the spine is fracture. Fractures or cracks in the bone can occur due to osteoporosis or accident, and they can cause severe low back pain. The treatment most often includes rest, pain relievers and sometimes physical therapy.
Dr. Winfree emphasized that despite the very specific nature of these diagnoses and treatments, the patient must be seen as a whole person and that a multidisciplinary approach is best. He also talked about what he calls a “treatment ladder.” That is, “to start with the easiest, safest, and least invasive and progress to more complex and invasive measures only as simpler options fail.”
To learn more see our page on Lower Back Pain.
Image credit: Alexandr Mitiuc / Adobe Stock
Originally posted Feb 25, 2010
Updated March 2, 2017
In Blog, Gamma Knife Blog, Pain Center Blog, Peripheral Nerve Blog Tags: , chronic low back pain, Dr. Winfree, epidural space, facet joint, intervertebral disc, low back pain, sacroiliac joint