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B. The Vertebral Column (Spine) *Vertebral column extends from skull to pelvis 1. Vertebrae: irregular shaped bones that make up the spine -24 single vertebrae: 7 cervical, 12 thoracic, 5 lumbar -plus 1 sacrum (5 fused vertebrae) & 1 coccyx (4 fused vertebrae) 2. Intervertebral discs: pads of flexible fibrocartilage that separate the single vertebrae; cushion vertebrae & absorb shocks Side note: herniated discs are “slipped” discs that protrude outward from normal position due to drying of discs & weakened ligaments or caused by exceptional twisting forces Figure 5.14 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings B. Vertebral Column (Spine) 3. S-shaped curvature (refer to fig. 5.14 & 5.15) -normal skeleton has an S-shape -cervical region—anteriorly curved (concave) -thoracic region—posteriorly curved (convex) -lumbar region—anteriorly curved -sacral & coccygeal regions—posteriorly curved Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings B. Vertebral Column (spine) 3. S-shaped curvature continued a. scoliosis: abnormal lateral curvature b. kyphosis: hunchback; abnormal posterior curvature of spine mostly in upper thoracic region c. lordosis: swayback; abnormal anterior curvature of spine mostly in lumbar region Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fig 5.15 B. Vertebral Column (spine) 4. Similar features of typical vertebrae a. body or centrum: disclike, weight-bearing part of vertebra facing anteriorly in vertebral column b. vertebral arch: arch formed from the joining of all posterior extensions, the laminae and pedicles, from the vertebral body i. laminae—extend from transverse processes to spinous process ii. pedicles—extend from body to transverse processes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings B. Vertebral Column c. vertebral foramen: canal through vertebra that spinal cord passes through d. transverse process: 2 lateral projections from vertebral arch e. spinous process: single posterior projection f. superior/inferior articular processes (facets): paired projections lateral to vertebral foramen; allow vertebra to form joints with adjacent vertebrae Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structure of a Typical Vertebrae Figure 5.16 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings