Vertebrae Vertebral column Extends from skull to pelvis
Vertebrae
Vertebral column • Extends from skull to pelvis • Consists of many vertebrae separated by cartilaginous intervertebral disks that are connected by ligaments • Forms central axis of the skeleton
• Supports the head and the trunk of the body • Flexible to permit movements • Protects the spinal cord
How many vertebrae do we have? • Adult: 26 • Infant: 33 separate bones – Five vertebrae fuse to form the sacrum and four others join to become the coccyx
Components of vertebral column • • • Cervical vertebrae Thoracic vertebrae Lumbar vertebrae Sacrum coccyx
Curvatures of vertebral column fig 7. 34 • Names correspond to the regions in which they occur • 1. thoracic concave anteriorly (primary • 2. pelvic curves) • 3. cervical • 4. lumbar convex anteriorly (2 ndary curves)
3 parts of Vertebra • Body: (centrum) – Transfers weight along the axis; separated by intervertebral discs • Arch: surrounds vertebra foramen • Articular process: – Intervertebral foramina: gaps b/t ea vertebra; permits passage of nerves to or from spinal cord
Cervical Vertebrae • Comprise the bony axis of the neck • Smallest of the vertebrae, but tissue are denser than those in any other region of column • Allows for 180 degree range of motion • Atlas: (C 1) holds up head – Practically no body or spine – Pivots around the dens of axis • Axis: (C 2) during development fuses with atlas
• Atlas: (C 1) holds up head – Practically no body or spine – Pivots around the dens of axis • Axis: (C 2) during development fuses with atlas
Atlas
Axis
Distinctions of Cervical • Transverse processes of cervical are DISTINCT b/c of transverse foramina – Passageways for arteries leading to the brain • Spinous processes: Uniquely forked (bifid): provide attachment for muscles • Vertebra prominens: longer and protrudes beyond other cervical (can be felt thru skin)
Thoracic Vertebrae • Total of 12 • Larger than cervical • Long pointed spinous process slopes downward • Bear increasing loads of body weight due to the increase in the body size of the vertebra
Thoracic • Demi facets: on side of body to articulate with ribs • Injury: compression-dislocation fractures of vertebrae occur b/t throacic and lumbar due to heavy weight bearing load
Lumbar • Total of 5 in small of back • Supports more weight b/c of larger and stronger bodies • Transverse processes project posteriorly at sharp angles • Large Bodies
Lumbar • Short spinous processes are nearly horizontal: provide surface area for muscle attachment of lower back muscles • Smaller vertebral foramen • Injuries: Compression, Slip Disk
Sacral Vertebrae fig 7. 39 • Originates as 5 vertebrae • Complete fusion by age 25 (18 -30)
• Dorsal sacral foramina: blood vessels pass thru • sacral promontory: first sacral vertebra • Sacral canal: opening • Sacral hiatus: opening at end of sacrum • Sacral foramina: 4 pairs that provide passageways for blood vessels and nerves
Coccygeal • Originates as 4 vertebra, fuses as 1 bone • Fusion of time varies • Attached by ligaments to margins of the sacral hiatus
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