Similarly, the coccyx, or tailbone, results from the fusion of four (or in some cases 3 or 5) small coccygeal vertebrae. The single sacrum, which is also part of the pelvis, is formed by the fusion of five sacral vertebrae, though in about 33% percent of the population T12 is fused to the sacrum or S1 remains unfused. The lower back contains the L1–L5 lumbar vertebrae. Below these are the 12 thoracic vertebrae, designated T1–T12. Inferiorly, C1 articulates with the C2 vertebra, and so on. Superiorly, the C1 vertebra articulates (forms a joint) with the occipital condyles of the skull. In the neck, there are seven cervical vertebrae, each designated with the letter “C” followed by its number. The vertebral column is subdivided into five regions, with the vertebrae in each area named for that region and numbered in descending order. The vertebral column originally develops as a series of 33 vertebrae, but this number is eventually reduced to 24 vertebrae, plus the fused vertebrae comprising the sacrum and coccyx. The vertebral column is curved, with two primary curvatures (thoracic and sacrococcygeal curves) and two secondary curvatures (cervical and lumbar curves). The vertebrae are divided into three regions: cervical C1–C7 vertebrae, thoracic T1–T12 vertebrae, and lumbar L1–L5 vertebrae. Figure 7.4.1 – Vertebral Column: The adult vertebral column consists of 24 vertebrae, plus the fused vertebrae of the sacrum and coccyx. It also protects the spinal cord, which passes through openings in the vertebrae. It is a flexible column that supports the head, neck, and body and allows for their movements. Together, the vertebrae and intervertebral discs form the vertebral column. It consists of a sequence of vertebrae (singular = vertebra), each of which is separated and united by a cartilaginous intervertebral disc. The vertebral column is also known as the spinal column ( Figure 7.4.1). Determine the location of the ligaments that provide support for the vertebral column.Define the structure of an intervertebral disc.Describe a typical vertebra and determine the distinguishing characteristics for vertebrae in each vertebral region and features of the sacrum and the coccyx.Discuss the curves of the vertebral column and how these change after birth.Describe each region of the vertebral column and the number of bones in each region.By the end of this section, you will be able to:ĭiscuss the vertebral column and regional variations in its bony components and curvatures
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