Dalley, 10th Edition

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Vertebral Column

C

C

D

D

S S C

D

C1

C1

2

C2

C2

(C) Transverse CT

C3

C3

C4

C4

1 / 3 Dens ( D )

± 1 / 6 Space ( S ) 1 / 3 Spinal cord ( C )

1

(B) Lateral view

(A) Lateral view

± 1 / 6 Space ( S )

(D) Superior view

FIGURE B2.20. Median atlantoaxial joint trauma: rupture of transverse ligament of atlas or fracture of den. A. Subluxation of the median atlantoaxial joint results from rupture of the transverse ligament. The atlas moves, but the dens is xed. B. Fracture of the dens shows that the dens and atlas move together as a unit because the transverse ligament holds the dens to the anterior arch of the atlas. C and D. Normal median atlantoaxial joint and demonstrating Steele’s Rule of Thirds.

Rupture of Alar Ligaments

curvature, and colloquially known as humpback or hunch back ) is characterized by an abnormal increase in the tho racic curvature; the vertebral column curves posteriorly (Fig. B2.21B, F). This abnormality can result from erosion (due to osteoporosis) of the anterior part of one or more vertebrae. Dowager hump is a colloquial name for excessive thoracic kyphosis in postmenopausal women resulting from osteoporosis. However, this type of kyphosis also occurs in elderly men. Osteoporosis especially affects the horizontal trabeculae of the trabecular bone of the vertebral body (see Figs. B2.9C and B1.5 in Chapter 1, Overview and Basic Concepts). The remaining, unsupported vertical trabeculae are less able to resist compression and sustain compression fractures, result ing in short and wedge-shaped thoracic vertebrae. Progres sive erosion and collapse of vertebrae also result in an overall loss of height. The excessive kyphosis leads to an increase in the AP diameter of the thorax and a signi cant reduction in dynamic pulmonary capacity. Excessive lumbar lordosis (clinically shortened to lordosis , although once again, this term actually describes the normal curvature; colloquially, excessive lumbar lordosis is known as hollow back or sway back) is characterized by an anterior tilting of the pelvis (the pelvis—including the sacrum—is ro tated anteroinferiorly— nutation ), with increased extension of the lumbar vertebrae, producing an abnormal increase in the lumbar lordosis (Fig. B2.21C).

The alar ligaments are weaker than the transverse ligament of the atlas. Consequently, combined exion and rotation of the head may tear one or both alar ligaments. Rupture of an alar ligament results in an increase of approximately 30% in the range of movement to the contralateral side (Dvorak et al., 1988). Abnormal Curvatures of Vertebral Column To detect an abnormal curvature of the vertebral column , have the individual stand in the anatomi cal position. Inspect the pro le of the vertebral col umn from the person’s side (Fig. B2.21A–C) and then from the posterior aspect (Fig. B2.21D). With the per son bending over, observe the ability to ex directly forward and whether the back is level once the exed position is as sumed (Fig. B2.21E). Abnormal curvatures in some people result from devel opmental anomalies; in others, the curvatures result from pathological processes. The most prevalent metabolic dis ease of bone occurring in the elderly people, especially in women, is osteoporosis (atrophy of skeletal tissue). Excessive thoracic kyphosis (clinically shortened to ky phosis, although this term actually applies to the normal

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