Back Pain Anatomy: Topics

The back includes the bones that make up the spine, the spinal cord housed within the vertebral foramen of the bones, and the supportive structures that are involved with the movement, stability, and nourishment of the spine. The spine exists as its own structure to support the central nervous system, but it also serves the dorsal point of attachment for the ribs as well as other beneficial functions of the body. Thus far, many of the web pages here have focused on the vertebral column itself, as well as the spinal nerves that exit through its side and branch of to become the peripheral nervous system of the body.

Here we will turn the page and take a closer look at the muscles which support the spine for movement and stability.

The anatomy of the back muscles: While X-Ray images, CT Scans, and MRIs may offer doctors a lot of diagnostic information about the structures of the spine itself, back pain may be caused by problems with the soft tissues that support the spine. In and surrounding the spine, there are large and complex muscle groups that either work together or antagonistically to bend and turn the spine, or to hold the structures in positions that enable them to protect the spinal nerves. The large and complex muscle groups allow us to stand and walk upright, and it gives the spine the flexibility to rotate or bend in every direction.

The three types of back muscles that are the most prominent in initiating the movements of the spine are the extensor, flexor, and oblique muscles. These muscles insert onto one of the processes of the vertebral bones on one end and attach to one of the bones on outside of the spine.
  • The extensor muscles contract to extend the back so that we may perform the actions of standing, holding an upright position, and lifting objects. These muscles attach to the dorsal (back) side of the vertebral bones. The extensor muscles include the gluteal muscles, and the erector spinae muscles. The flexion of these muscles allows back to extend and the relaxation of these muscles may allow the spine to bend forwards.
  • The flexor muscles attach to the front of the spine, and the contractions of these muscles allow us to bend forward, flexion of the spine, lifting, and arching of the back. The flexor muscles include the abdominal muscles, including the Psoas major, transverse abdominus, rectus abdominus, and internal oblique muscle.
  • The oblique muscles attach to the sides of the spine, such as the transverse processes of the vertebral bones, and enable the actions of rotation of the spine and the maintenance of a proper posture when working and when the body is at rest. The oblique muscles of the back/spine include the Serratus anterior, internal oblique, and external oblique. No all of these muscles connect directly to the vertebral column.

Muscles Weakness, Muscle Imbalances, and Lower Back Pain: In the human spine, you have muscles pulling from all sides where they attach to the vertebral column. When one muscle or muscle groups are pulling harder from one side of the spine, the body will bend or rotate in that particular direction. When the body is in a state of rest, the muscle groups together should pulling in forces that equal each other out - holding the spine in a stable position. When there is weakness to the muscles on one or more sides of the body, then this stability of the spine may be disrupted, causing poor posture or pressure on the soft tissues of the spine, including the discs and the ligaments. Thus weakness and muscular deconditioning are two common causes of lower back problems and back pain.

The good news about muscle weakness and back pain is that it is correctible with simple exercises that can be done with simple gym equipment and at home. While muscles like the calf muscles and the gluteals in the thighs get used regularly over the course of the day, other muscles deep in the abdomen may be seldom challenged unless you are in some type of exercise program. These muscles tend to weaken when they are underused, as well as lose their mass and strength as we age. Here are some exercises that you can do at home to challenge the interior abdominal muscles.

Pelvic Tilt: With this exercise, you will lie in the floor with your back and arms flat to the ground, your knees up, and the soles of your feet flat to the ground.
  • Without using your leg muscles or buttocks, tighten your abdominal muscles, pulling your naval and lower back to the floor.
  • This exercise challenges and strengthens the oblique muscles and the lower abdominal muscles.
Trunk Curl: With this exercise, you will lie on the floor, with your back flat to the ground, your knees bent, and the soles of your feet flat to the ground. Cross your arms across your chest.
  • While only using the muscles of your upper abdomen, slowly raise the trunk of your body off the floor, about 15 degrees.
  • Hold this position for 5-10 seconds.
  • Slowly lower your trunk back to the floor.