Understanding Your Low Back - Part I

Saturday, July 1, 2006 | 0

By Jomar Almeda, MD

"Man is ill because he is never still." - Paracelsus (1493-1541)

In order to have a better understanding of low back symptoms and its many causes, it is necessary to have a general knowledge of its basic structure and function. Low back symptoms can be brought about by conditions arising from the lumbar spine, the spinal cord and nerves, muscles, ligaments, retroperitoneal organs, and from any of the internal organs within the abdomen and pelvis. Low back pain accounts for a great number of work-related medical conditions. But while symptoms can arise from any area of the back, the most commonly involved part is that of the lumbar spine.

THE VERTEBRA:

From the Latin word "vertere", which means to turn, the vertebra, collectively known as vertebrae, are the individual bones that make up the vertebral (spinal) column. This longitudinal structure of neatly stacked bones permits the spine to bend, extend, and twist.

The vertebral column has 33 vertebrae, that is divided into segments representing the region they occupy. There are 7 cervical (neck) vertebrae, 12 thoracic (mid-back) vertebrae, and 5 lumbar (low back) vertebrae. Below the lumbar spine is the sacrum, consists of 5 fused vertebrae, which connects the rest of the spine to the pelvis, and the 4 fused bones of the coccyx, commonly called the tail bone.

Although the vertebral bodies in the lumbar spine are more massive and stronger than the rest, their greater mobility and lowermost position which bears the majority of the bodys weight, make them more vulnerable to injury.

THE DISC:

Between each vertebrae are the intervertebral discs which act as cushions that absorb shock, and maintain the spines flexibility. The human spine has 23 discs. 6 are in the cervical region, 12 are in the thoracic region, and 5 are in the lumbar region.

The disc is made up of an inner nucleus pulposus, and an outer concentric layer called the annulus fibrosus. The bodys weight when in an upright position exerts a tremendous amount of pressure on the gelatinous nucleus pulposus, from which multi-directional movement of the lumbar spine also occurs. The annulus fibrosus confines the nucleus pulposus within its bounds, and keeps it from herniating when pressure is applied.

THE SPINAL CORD:

In the lumbar spine, each vertebral body forms an arch posteriorly, to create a longitudinal enclosure called the spinal canal. The spinal canal houses the spinal cord which extends from the base of the brain, and runs down the back. The spinal cord carries motor signals from the brain that controls the movement of skeletal muscles. Sensory signals received by the brain from various parts of the body are also transmitted by the spinal cord. These motor and sensory branches of the cord which are situated ventrally (anterior) and dorsally (posterior) respectively, forms the spinal nerves. The 31 pairs of spinal nerves contributed by each segment of the different spinal regions (cervical, thoracic, lumbar, sacral, coccygeal) exit the spine through spaces (foramen) between the vertebrae.

The spinal cord ends at or about the level of the lower thoracic or the first lumbar vertebra. From its termination, the spinal nerves then continue as a bundle of nerves called the cauda equina. Therefore, since the lumbar spinal canal no longer has a spinal cord, it has a relatively large amount of space compared to the cervical or thoracic regions. For this reason, severe complications are unlikely even in the presence of a large disc bulge or herniation in the lumbar spine.

THE NEARBY ORGANS:

Equally important in understanding symptoms coming from the low back is knowledge of nearby organs which can also play a role in back pain. The kidneys lie just beneath the ribs in the mid-back region. The ureters which are ducts that carry urine from the kidneys to the urinary bladder in the pelvic area, are located in the lower back, along with portions of the intestines and the aorta, the largest artery in the human body. In females, disorders of the ovaries and uterus must also to be considered as damage to these organs can also cause back pain.

Jomar, a graduate of a comprehensive WorkCompSchool program, is now sharing his professional expertise in WorkCompSchool's faculty, with a premier online course currently in the production stages. He can be reached at jomar@lamedcenter.com.

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