Axial Bones
Composition :
vertebrae（24）
sacrum （1）
coccyx（1）
sternum（1）
ribs（24）
Cervical vertebra :
a.the body: small
b. transverse foramen
c. spinous processes :
short and bifid (except 1，7 cervical vertebrae)
d. vertebral foramen : triangular and relatively large
Atlas:the first cervical vertebra.
It looks like an irregular ring .
anterior arch ⑴
posterior arch ⑵
lateral mass
dental fovea ⑶
groove for vertebral artery⑷
Body and spinous process absent, consists of anterior and posterior arches, and two lateral masses.
Axis:
the second cervical vertebra.
dontoid process .
Vertebra prominens:
the seventh cervical vertebra.
long and nonbifid
apinous process.
Thoracic vertebrae:
superior costal foveae ⑴
inferior costal foveae ⑵
transverse costal fovea ⑶
The spinous processes are long, thin and posterodownward sloping.
Lumbar vertebrae :
large, thick bodies
The spinous processes are heavy, rectangular and strong, with posterior directions
The vertebral foramen is triangular, but larger than that in the thoracic region．
Sacrum and Coccyx :
sacral promontory ⑴
anterior sacral foramina ⑵
posterior sacral foramina ⑶
sacral canal ⑷
superior articular processes⑸
sacral hiatus ⑹
transverse lines ⑺
The coccyx is composed of 4-5 fused coccygeal vertebrae after the age of 30 years. ⑻
Sternum :
True ribs : the upper 7 ribs, reach to the sternum anteriorly. (1-7)
False ribs: the lower 5 ribs, fail to reach the sternum. (8-12)
Costal arch ------the 8-10th ribs join the costal cartilage immediately
above to form the costal arch.
Floating ribs------the cartilage of the last two ribs are free.
General features of costal bone :
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