Understanding the Mechanics of Back Pain
Preventing Injury by Moving the Spine Correctly
Apr 24, 2009
According to the National Institute of Neurological Disorders and Stroke, “Americans spend at least $50 billion each year on low back pain, the most common cause of job-related disability and a leading contributor to missed work” (July, 2003). Understanding how the structures of the spine are designed will provide answers as to how to protect them from injury.
Anatomy of the Spine
The spine is made up of a series of individual vertebrae. The vertebrae are divided into different sections including the body, the spinous process, and transverse processes. The body of the vertebrae is the largest part of the vertebrae and is designed to handle the compressive loads of the body.
The bodies of the cervical vertebrae are smaller in height and diameter than the bodies of the thoracic and lumbar spine. The bodies of the lumbar spine are the thickest of the spine enabling them to handle the increasing weight of the body.
In between and along side of each vertebrae are small ligaments that stabilize each motion segment (vertebrae, intervertebral disc, vertebrae). Ligaments connect bone to bone and are designed to restrict motion. Ligaments can be injured through any force that exceeds the strength of the ligament tissue (forceful twist, or bend).
Providing cushions to absorb the compressive loads in between the vertebrae are the intervertebral discs. The outer part of the disc is made up of dense connective tissue (to restrict excessive motion) while the inside is made up of a thick gelatinous-type material for the sole purpose of cushioning and distributing the compressive loads.
Intervertebral Disc Injuries
The discs can be injured in a number of ways, but primarily through an extension movement of the spine (straightening) in combination with a twisting movement. In other words, straightening the spine from a twisted position places the disc at risk for serious injury.
This type of movement compresses the disc (picture a balloon) on the bent side and can rupture the disc on the opposite side. The ruptured material from the inner portion of the intervertebral disc can leak out and put pressure on one of the spinal nerves causing significant pain to the patient.
Along with disc injuries, muscle strains can cause significant pain. Because the back muscles have the ability to splint themselves (spasm to protect injured tissue), pushing through a muscle strain only causes more pain.
The key to preventing muscle strains is in understanding how to properly utilize the muscles of the back and lower extremity. The back muscles responsible for extending the spine are a series of small muscles that run up and down the spine. These muscles are not designed to handle heavy loads. Loads that exceed the tensile force of the muscles will result in a muscle strain.
Preventing Muscle Strain by Proper Lifting
The muscles that are designed to handle heavy loads are the large muscles of the pelvis, hip, and thigh. These muscles include the three gluteus muscles, the four quadriceps muscles, and the three muscles that make up the hamstring muscle group. Due to their structure and line of pull, these muscles are perfectly designed to handle heavy loads.
The structures of the spine can be easily injured if the spine is placed in a position to extend and twist while lifting a heavy load. This type of movement can injure spinal ligaments, muscles, and intervertebral discs.
To prevent injuries, individuals need to lift heavy loads with their legs while keeping their spine straight and their core muscles tight. This enables the body to use the large muscles of the legs to lift while protecting the small muscles of the spine.
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