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B. Vertebral Column (spine)5. Cervical vertebrae—7

-form the neck region of spine

-the first 2 (atlas & axis) are unique in their structure & function

a. atlas (C1): first cervical vertebra

-contains no body

-occipital condyles of skull articulate with atlas

-the bone responsible for allowing you to nod head “yes” (atlas = the “yes” bone)

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ATLAS: Has superior surfaces of transverse processes have depressions that articulate with occipital condyles of skull

ATLAS: Has no body

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B. Vertebral Column (Spine)b. axis (C2): acts as a pivot for rotation of the

atlas & skull above it

i. dens (odontoid) process—acts as the pivot point

-the joint between atlas & axis allows you to shake head “no”

-axis= the “no” bone

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B. Vertebral Column (spine)c. typical cervical vertebrae

(C3-C7):

-smallest, lightest vertebrae

-usually have short spinous processes that are often divided into 2 branches

-transverse processes contain foramina (openings/holes) that arteries pass through

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Characteristics of Cervical Vertebrae

Figure 5.17a–b

CERVICAL

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

B. Vertebral Column (Spine)6. Thoracic vertebrae—12

-labeled T1-T12

-larger than cervical vertebrae

-body is somewhat heart-shaped

-extra set of facets for ribs

-long, thin spinous process

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B. Vertebral Column (Spine)7. Lumbar vertebrae—5

-labeled L1-L5

-have massive, blocklike bodies

-short, hatchet-shaped spinous processes

-the sturdiest of the vertebrae since most of stress on vertebral column occurs here

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Characteristics of Thoracic & Lumbar Vertebrae

Figure 5.17c–dTHORACICLUMBAR

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B. Vertebral Column (Spine)8. Saccrum—1

-formed by the fusion of 5 vertebrae

-connects superiorly to L5 and inferiorly to coccyx

-joins to hip bones at sacroiliac joints

EXTRA CREDIT

* median sacral crest: the fused spinous processes of sacral vertebrae; found on midline of sacrum

*sacral canal: continuation of vertebral canal

* sacral hiatus: large inferior opening; termination of sacral canal

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B. Vertebral Column (Spine)9. Coccyx—1

-formed from fusion of 3 to 5 tiny, irrgular shaped vertebrae

-usually called the “tailbone”