![]() ![]() On rare occasions, they may be particularly prominent. The accessory processes are found at the posterior aspect of the transverse processes (Figs. 8 ), may remain ununited, or may support a small lumbar rib ( F21Fig. How ever, the L1 transverse process may retain a tripartite configuration ( F20Fig. The L1 transverse processes lose the D12 tripartite configuration as the superior, lateral, and inferior tubercles turn into mammillary, transverse, and accessory processes, respectively. The L1, L2, and 元 transverse processes are slender and horizontal. These features help differentiate these anomalies from fractures. ![]() These centers have smooth rounded borders, resembling typical accessory ossicles. Persistent secondary ossification centers may occur ( F19Fig. They adopt a transitional tripartite configuration at D12 (occasionally at D10, D11, or L1). The transverse processes have a costal facet from D1 through D9 but may or may not have a costal facet at D10. They have no foramen transversarium and end in a clubbed extremity. ![]() The transverse processes of the dorsal spine are thick, strong, and considerably long, particularly at D1. Cervical ribs may be rudimentary or fully developed and may cause thoracic outlet syndrome. The anterior tubercle of the transverse process of C7 is frequently small or absent, but it may attain a large size or may exist as a separate bone to form the cervical rib (Figs. 5 ) or triple, or may be absent at C1 or C7. The foramen transversarium varies in size and shape, may be anteriorly open, may be double ( F16Fig. The transverse processes of typical cervical vertebrae are pierced by the foramen transversarium. However, both facet joints tend to be more sagittally oriented in patients with degenerative spondylolisthesis. Investigators have suggested that facet joint tropism does not significantly increase the risk of facet joint osteoarthritis or disk degeneration. 4A, 4B, 4C, 4D, and 4E ), but the definition of excessive tropism is arbitrary. Some individuals show asymmetric facet joint angles (Figs. įacet tropism is defined as asymmetry at the facet joint angles of the lumbosacral region. Absent facet joints may be associated with a conjoined nerve root and may cause low back pain. Fused facet joints may be seen in segmental anomalies and various neural arch malformations. Īrticular processes may be hypoplastic ( F9Fig. Accessory ossicles at the superior joint facet may also occur. 3A, 3B, and 3C ), which may be mistaken for a facet fracture, originates from a horizontal cleft through the inferior articular process. ![]() It can be associated with a hypoplastic pedicle or a dysplastic facet joint (Figs. 1A, 1B, 1C, 1D, and 1E ).Ī vertical cleft through the superior articular process may occur. This feature, termed the “two-eyed scotty dog” sign, may be easily reproduced on oblique sagittal volume-rendered MDCT images (Figs. On an oblique radiographic view, it is seen as a ring-shaped opacity adjacent to the pedicle. A prominent mammillary process may be hard to identify on anteroposterior radiographs of the lumbar spine. It arises from a secondary ossification center and may persist into adult life. The mammillary process is a normal elevation at the posterior margin of the superior articular facet. The change of orientation is gradual from the cervical to thoracic region and is rather sudden from the thoracic to lumbar region. Their shape and orientation show regional differences throughout the spine, with transition points around C6 and T11. The articular processes arise from the junction of the pedicles and laminae. ![]()
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