Muscles Move and Support the Spine
There are two basic types of muscles in the body: voluntary (those we move) and involuntary (those that move on their own, such as digestive and heart muscles). Both types can get stronger and more resilient through exercise. We're going to focus on the voluntary muscles that move and support the spine. Lack of muscle strength and flexibility is a common reason for back pain.
Muscles are layered in the body. Some are deeper and others more superficial or at the surface. The deeper muscles are more stabilizing—helping to secure bones. Abdominal and back muscles are detailed in the following illustration. Muscles of the hips and legs can also play a part in back problems, but we'll get into their roles in the exercise section of this book.
Your doctor may have already told you that to have a healthy back you need strong abdominal muscles, which help stabilize your whole torso. There are four types of abdominal muscles.
The deepest, transversus abdominis, hugs around your body like a corset. You can feel these muscles contract if you place your hands on your waist and cough. On the sides of your body, you have two sets of "oblique" muscles, the internal obliques are deeper, the external obliques lie closer to surface. Obliques enable you to twist and side bend.
Finally, there's rectus abdominis, better known as the "six pack." Although you can sculpt these into those desirable washboard abs (with a whole lot of work), they're not particularly helpful in stabilizing your back. Their main job is to pull you forward (think sit-ups and crunches). They do help you compress the deeper ab muscles, but when it comes to stabilizing the spine, you want to strengthen the deepest ab muscles, transversus and internal obliques, along with the back muscles. Among the most effective ab and back workouts are Pilates exercises, which target all abdominal and spine muscles quite well.
Deep within the body are two muscles, one on either side of the body, called the iliopsoas muscles, or the psoas (pronounced so-as). These are hip and thigh flexors, meaning they lift the thighs, as in going upstairs, walking. When your legs are stationary, the psoas enable you to bend forward or flex in the hips. When sitting, the psoas help stabilize you in an upright position. One of the largest and thickest muscles in the body, the psoas extend from your lumbar vertebrae, cross in front of each hip, and attach on the inside-top of the thigh bone. Sitting for long periods can constrict or shorten psoas, which can cause pain upon standing.
Like your abs, spinal muscles are layered. The deepest are small and attach one vertebra to one another. At the deepest level, interspinalis muscles connect to your spinous processes; thank them for helping you stretch backward. The transversospinalis group forms a chevronlike pattern along the back of your spine and helps you side bend and twist, and it also assists in back bending. The next layer up is the erector spinae. The main job of this group is also back bending, although they also assist with side bending. Often when we get muscle spasms in the back, it's in the erector spinae muscles.
The next level consists of the rhomboids, between your shoulder blades, which through exercise or physical therapy can help realign your vertebrae. The very large, wing-like muscles on either side of your back are called latissmius dorsi. In addition to stabilizing the back, these muscles help you do all kinds of things, including pull-ups. Finally, the trapezius muscles extend from your neck and midback to your shoulders. These muscles help you move your neck and lift your shoulder blades. When we get tense, we tend to lift our shoulders, which can make these muscles quite tight and sore.
Muscles connect to bones through tendons. When a muscle contracts,the signal is concentrated through the tendon, which moves the bone. Tendons are firmly attached to bones. Although it isn't common, tendonitis, or inflammation of tendons, can occur even in the spine.
Jason Highsmith, MD is a practicing neurosurgeon in Charleston, NC and the author of The Complete Idiot's Guide to Back Pain. Click here for more information about the book.