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The vertebral column is an amazingly complex structure that must meet the seemingly contradictory demands of mobility and stability for the trunk and the extremities and of protection for the spinal cord. Although the pelvis is not considered part of the vertebral column, the pelvic attachment to the vertebral column through the sacroiliac joints will be included in this chapter because of the relationship of these joints and those of the lumbar region.

Case 4-1: Patient Case

Our patient, Malik Johnson, is a 33-year-old male construction worker who for several months has been experiencing moderate to severe low back pain that radiates into his right lower extremity. He has pain with sitting, carrying, and all lifting activities, especially activities that involve lifting from a stooped position. He also has pain with upper extremity tasks such as hammering and using power tools. The pain is particularly severe when he first gets to work in the morning and when he performs any of these activities. He can relieve the pain somewhat if he lies down, but he has been able to tolerate work for only approximately four hours at a time. His history includes several episodes of low back pain that were severe but much shorter in duration, lasting for only a few days.



The vertebral column resembles a curved rod, composed of 33 vertebrae and 23 intervertebral discs. The vertebral column is divided into the following five regions: cervical, thoracic, lumbar, sacral, and coccygeal (Fig. 4–1A). The vertebrae adhere to a common basic structural design but show regional variations in size and configuration that reflect the functional demands of a particular region. The vertebrae increase in size from the cervical to the lumbar regions and then decrease in size from the sacral to coccygeal regions. Twenty-four of the vertebrae in adults are distinct entities: Seven vertebrae are located in the cervical region, twelve in the thoracic region, and five in the lumbar region. Five of the remaining nine vertebrae are fused to form the sacrum, and the remaining four constitute the coccygeal vertebrae.

Figure 4–1

Five distinct regions of the vertebral column.

In the frontal plane, the vertebral column bisects the trunk when viewed from the posterior aspect (Fig. 4–1B). When viewed from the sagittal plane, the curves are evident (Fig. 4–1A). The curve of the vertebral column of a fetus exhibits one long curve that is convex posteriorly; secondary curves develop in infancy (Fig. 4–2 A,B,C). However, in the column of an adult, four distinct antero-posterior curves are evident (Fig. 4–2D). The two curves (thoracic and sacral) that retain the original posterior convexity throughout life are called primary curves, whereas the two curves (cervical ...

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