1. 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

2. 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

3. 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

4. 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

6. 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

8. 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

9. 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”

10. 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”

11. Cervical Vertebra: C3-C7 Smallest, lightest vertebrae Spinous process are divided into 2 branches (bifid) Transverse processes contain foramina for arteries to pass through

12. 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.

14. Lumbar Vertebrae L1 through L5 Largest & strongest Spinous processes are well adapted for the attachment of the large back muscles

15. 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

17. 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