Dalley, 10th Edition

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Vertebrae

Long, strong transverse processes extend posterolaterally

Transverse process

Nearly vertical articular facets directed primarily posteriorly and anteriorly Circular vertebral foramen, relatively small compared to size of body

Columnar bodies, heart-shaped in superior view

Triangular vertebral foramen

Uncus of body (uncinate process) Rectangular bodies with concave superior and convex inferior surfaces

Bifid spinous process

2

Oblique, relatively horizontal articular

facets directed primarily superiorly and inferiorly

Foramen transversarium

(B) Superolateral view, thoracic vertebra Spinous process long and sloping; overlaps inferior vertebra Vertebral foramen triangular, intermediate in size

Perforated transverse processes with anterior and posterior tubercles

Costal facets 2 on each side of body 1 on each transverse process

(A) Superolateral view, cervical vertebra

Short, broad, and blunt spinous process

Massive columnar body, kidney-shaped in superior view

Transverse processes long and slender, directed laterally

Nearly vertical articular facets directed primarily medially and laterally

(C) Superolateral view, lumbar vertebra

FIGURE 2.6. Comparison of typical presacral vertebrae. As the vertebral column descends, bodies increase in size in relationship to increased weight bearing. The size of the vertebral canal changes in relationship to the diameter of the spinal cord.

Regional Characteristics of Vertebrae Each of the 33 vertebrae is unique; however, most of the vertebrae demonstrate characteristic features identifying them as belonging to one of the ve regions of the vertebral column (e.g., vertebrae having foramina in their transverse processes are cervical vertebrae) (Fig. 2.6). In addition, cer tain individual vertebrae have distinguishing features; the C7 vertebra, for example, has the longest spinous process. It forms a prominence under the skin at the back of the neck, especially when the neck is exed (see Fig. 2.10A). In each region, the articular facets are oriented on the articular processes of the vertebrae in a characteristic di rection that determines the type of movement permitted between the adjacent vertebrae and, in aggregate, for the re gion. For example, the articular facets of thoracic vertebrae are nearly vertical and together de ne an arc centered in the IV disc. This arrangement permits rotation and lateral exion

The spinous and transverse processes provide attachment for deep back muscles and serve as levers, facilitating the muscles that x or change the position of the vertebrae. The articular processes are in apposition with corre sponding processes of vertebrae adjacent (superior and inferior) to them, forming zygapophysial ( facet ) joints (Figs. 2.2B and 2.5C). Through their participation in these joints, these processes determine the types of movement permitted and restricted between the adjacent vertebrae of each region. The articular processes also assist in keeping adjacent vertebrae aligned, particularly preventing one vertebra from slipping anteriorly on the vertebra below. Generally, the ar ticular processes bear weight only temporarily, as when one rises from the exed position, and unilaterally, when the cervical vertebrae are laterally exed to their limit. How ever, the inferior articular processes of the L5 vertebra bear weight even in the erect posture.

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