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