Abdominal Muscles and Back Pain
Abdominal Muscles and Health of the Back and Spine
There are 4 major muscle groups involved in giving us the ability to bend forward as well as providing core strength and stabilization of the spine. The four main groups of abdominal muscles, beginning with the deepest muscle layer, and going outwards, are the Transverse abdominis, Internal oblique, external oblique, and Psoas muscles. These four muscles are closely associated with a medical and training term known as core strength. Individuals with strong core muscles as less likely to have back pain and lower back pain, studies have shown.
The muscles of the abdomen have the responsibility of helping the spine to bend forward, as well as moving the legs. The points of attachment among these muscle groups may be from the spine to the pelvis and femur and from the rib cage and sternum to the pelvis. If you look at the diaphragm, you can see that there are very few muscles attached to the front of the vertebrae to help the spine bend forward. The Psoas muscle is one exception, but its main function is to elevate and lower the leg.
The muscles that are involved in the forward bending of the spine involve the muscles of the abdominal wall, which include the internal oblique, external oblique, transverse abdominis, and rectus abdominis. The deepest layers, known as the obliquus internis and the obliquus externis run diagonally from the ribs to the hip bones. The middle layer, called the transverse abdominis, originates from several regions, including the six lower ribs, and connects with the iliac crest on each side of the body. The transverse abdominis crosses the innermost layer. The rectus abdominis, the outermost layer, runs vertically from about the level of the diaphragm, to the level of the pubic symphysis in the pelvis. The rectus abdominis, when well developed, is the muscle group that is most noticeable and is more commonly known as a six pack in a well conditioned athlete.
When these muscles are contracted, the spine bends forward. In addition to forward, bending, these muscle groups have other functions as well. To also pull the spine sideways, the muscles on one side of the spine only will be contracted, or a disproportionate amount of contraction will occur on one side of the body over the other.
These muscle groups also help us to sit and stand up straight with a minimal amount of conscious effort, and to hold the spine in it's optimum position. This occurs because these abdominal muscles pull the body forward to provide a counter balance against the muscles of the back that are trying to pull the spine backwards. The overall effect of these muscle groups is the neutral erect position that the majority of healthy people are able to maintain, with a minimum amount of effort or back pain.
When the erector spinae and the abdominal muscles are more or less equal in strength, their opposite pulls cancel each other out, and we are able to sit up and strand straight with a minimal amount of effort. When the muscles on one side of the spine or one side of the body are significantly weaker than the other, the spine may be thrown out of alignment, and at risk for injury and wear and tear.