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Axial Skeleton. The Vertebral Column. The Vertebral Column. Extends from skull (supports the skull) to the pelvis (distributes weight to lower limbs) Five sections: cervical, thoracic, lumbar, sacrum, coccyx Born with 33 vertebrae, but nine fuse into two bones (sacrum and coccyx)
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Axial Skeleton The Vertebral Column
The Vertebral Column • Extends from skull (supports the skull) to the pelvis (distributes weight to lower limbs) • Five sections: cervical, thoracic, lumbar, sacrum, coccyx • Born with 33 vertebrae, but nine fuse into two bones (sacrum and coccyx) • Vertebrae separated by intervertebral discs
The Vertebral Column – VertebraeStructure • Body/Centrum – disc-like part facing anteriorly • Vertebral arch – formed by joining of all posterior extensions of vertebra • Vertebral foramen – opening which spinal cord passes • Transverse processes – two lateral projections from arch • Spinous process – projection from posterior of arch • Articular processes – superior and inferior projections lateral to foramen that articulate with above vertebra
The Vertebral Column – Cervical Vertebrae • 7 vertebrae (identified as C1 to C7) • First two vertebrae are Atlas (C1) and Axis (C2) • Allow for the movement/rotation of skull • Do not have a body • Atlas articulates with the occipital condyles of the skull • C3 through C7 are remaining cervical vertebrae • Smallest vertebrae • Contain transverse foramen • Spinous processes usually split in middle
The Vertebral Column – Thoracic Vertebrae • 12 vertebrae (identified as T1 to T12) • Connected with ribs • Typical shape, slightly modified for ribs • Includes costal facets to articulate with ribs in posterior • Spinous process long, pointed down
The Vertebral Column – Lumbar Vertebrae • 5 vertebrae (identified as L1 to L5) • Bulkier shape • Hatchet-shaped spinous processes • Receives most of stress on vertebral column
The Vertebral Column – Sacrum and Coccyx • Sacrum is inferior to the L5 vertebra and superior to the coccyx • Formed from the fusion of five vertebrae • Alae are winglike projections that articulate laterally with the hip bones • Forms posterior wall of pelvis • Includes median sacral crest and dorsal sacral foramina • Coccyx is inferior to sacrum • Formed from fusion of three to five tiny vertebrae • Commonly called the “tailbone”