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Trauma to the spinal column can injure the bony elements (vertebral fracture) or the neural elements (spinal cord and nerve root injury), or both. The incidence of vertebral bone fractures is unknown, but there is better accounting of traumatic spinal cord injury because of the creation of state and national registries.1 Data from these organizations estimate the incidence of traumatic spinal cord injury in the U.S. to be 40 cases per million, with a mean age of 40 years old and a male-to-female predominance of 4 to 1. Spinal injury occurs more frequently on weekends and holidays and during summer months. The etiology of traumatic spinal cord injury is estimated to be 42% due to motor vehicle collisions, 27% due to falls, 15% due to acts of violence (primarily gunshot wounds), 8% from sports, and 8% from other mechanisms.

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The vertebral column is the central supporting structure for the head and trunk, and provides bony protection for the spinal cord. This column consists of 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused to form the sacrum), and 4 coccygeal, which are usually fused.

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Axial Vertebrae (C1 and C2)

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The axial cervical vertebrae are anatomically and functionally unique. Along with the occiput, these two vertebrae form complex articulations designed for rotary motion. The atlas (C1) consists of a ring formed by anterior and posterior arches and two lateral masses that articulate with the occipital condyles and the vertebral column. The axis (C2) consists of an anterior body—with a superior projection called the dens that articulates with the inner surface of C1—and a posterior vertebral arch that encircles the spinal cord. The dens is stabilized against the inner surface of the C1 ring by the transverse ligament.

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Subaxial Vertebrae

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In general, the vertebrae below C2 are fundamentally the same. In accordance with their weightbearing function, the vertebrae become larger toward the lower end of the vertebral column. A typical vertebra is composed of an anterior body and a posterior vertebral arch (Figure 255-1). The vertebral arch is comprised of two pedicles, two laminae, and seven processes (one spinous, two transverse, and four articular). These articulations enable the spine to engage in flexion, extension, lateral flexion, rotation, or circumduction (combination of all movements). The articular processes form synovial joints that act as pivots of the spinal column. The orientation of these articular facet joints changes at different levels of the spine. Differences in orientation of the facet joints account for variations in motion of specific regions of the vertebral column.

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Figure 255-1.
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Vertebral anatomy. Each vertebra consists of a vertebral body and posterior element. Vertebrae are stabilized by an anterior longitudinal ligament, posterior ligament, and interspinous ligament.

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A series of ligaments serve to maintain alignment of the spinal ...

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