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Vertebral Column
• Also called the spine or backbone• Composed of a series of bones called
vertebra• FUNCTIONS:
– rotate forward, backward, & sideways– protects the spinal cord– supports head– attachment point for ribs & back muscles
Regions of Vertebral Column
- Total # during early development: 33
- Total # in adults: 26• 7 cervical vertebra (neck)• 12 thoracic vertebra
(posterior to thoracic cavity)
• 5 lumbar vertebra (supports lower back)
• 1 sacrum (5 fused sacral vertebra); immovable
• 1 coccyx (4 fused vertebra); immovable
Regions of Vertebral Column
• The individual vertebrae are separated by pads of fibrocartilage called intervertebral discs – FUNCTIONS: form strong joints,
permits various movements, and absorbs vertical shock
– Herniated discs: Because of excessive twisting, the disc presses against the spinal cord or nerves, resulting in numbness or pain
Curves of the Vertebral Column
- There are 4 slight bends or normal curves• The cervical and lumbar curves are convex
(bulging out)• The thoracic and sacral curves are concave
(cupping in)• IMPORTANCE: increase strength; maintain
balance; absorb shock; protect it from breaks• Fetus- Single concave curve• Infant begins to hold head up- cervical curve
forms• Child sits, stands & walks- lumbar curve forms
Structure of Vertebra• Body: thick, disc-shaped; weight bearing part• Vertebral arch• Vertebral foramen: canal through which the
spinal cord passes• Transverse processes: 2 lateral projections from
the vertebral arch• Spinous process: single projection arising from
the posterior part of vertebral arch• Superior and inferior articular processes:
paired projections lateral to the vertebral foramen
Cervical Vertebra
• Termed C1 through C7• The first two vertebrae (atlas &
axis) are different because they perform functions not shared by the other cervical vertebrae
Cervical Vertebra • C1 is called the atlas• Lacks a body and a spinous process• Superior surfaces of its transverse
processes contain depressions that receive the occipital condyles of the skull– permits you to nod your head to indicate “yes”
Cervical Vertebra • C2 is called axis• Does have a body and spinous process• Has a tooth-shaped process called the dens
– Projects in the vertebral foramen– pivot on which the atlas and head rotate, allowing
the side-to-side rotation of the head to signify “no”
Cervical Vertebra: C3-C7
• Smallest, lightest vertebrae• Spinous process are divided into 2 branches (bifid)• Transverse processes contain foramina for arteries
to pass through
Thoracic Vertebrae
• T1 through T12• Considerably larger & stronger
than cervical• Only vertebrae to articulate with
the ribs– The transverse processes have facets
for connecting to the ribs.
Lumbar Vertebrae• L1 through L5• Largest & strongest• Spinous processes are well adapted for the
attachment of the large back muscles
Sacrum
• Formed by the fusion of 5 sacral vertebrae (S1 through S5)– Fusion begins around 16-18; completed by age 30
• 4 pairs of sacral foramina- nerves and blood vessels pass through
• Sacral canal- allows spinal cord to pass through– The lower entrance (sacral hiatus) is where an
epidural is injected during childbirth
Coccyx
• Triangular in shape• Formed by the fusion of 4
vertebrae (Co 1 through Co 4)– fusion occurs between ages 20 and
30 years old
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