Bones of Trunk

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 :