OSTEOLOGY AND SYNDESMOLOGY. 23 



The articular or oblique processes are four in number ; they arise fi'om the 

 roots of the transverse processes or from the pedicles ; two ascend, two 

 descend. They are covered with cartilage, and articulate with the corre- 

 sponding processes of the adjacent vertebrae. The two superior are directed 

 more or less backward, and the two inferior more or less forward; their 

 direction is rather vertical or contrary to that of the surface of the bodies, 

 beyond the level of which they extend, so that their articulations correspond 

 to the inter-vertebral ligaments. 



The spinal hole or canal is bounded by the body and processes ; it is more 

 or less triangular. 



The vertebrae are divided into three sets, all differing in size and shape. 

 The first set reckoned from below is the lumbar {pi. 122, ßg. 5 c), consisting 

 of the five bones immediately above the sacrum and at the lower extremity 

 of the column. They are the largest of all. The dorsal {ßg. 5 b) are twelve 

 in number, and are situated above the lumbar. They are intermediate in 

 size between the lumbar and the cervical. On each side of the body of a 

 dorsal vertebra there is a notch in the upper and lower margin. When two 

 vertebras are conjoined, the inferior notch of one is in apposition with the 

 superior notch of the vertebra beneath, and the two notches together con- 

 stitute an oval depression for the head of a rib. 



The cervical vertebroi {ßg. 5 a), seven in number, are the smallest of all, 

 and occupy the top of the column. The first or uppermost of all is called 

 the atlas {pi. 123, ßgs. 35, 36); it consists merely of a bony ring, without a 

 distinct body or spinous process. The laminae are thick and round behind, 

 but near the articulating processes they are flattened and grooved above 

 for the vertebral artery and first cervical nerve, and below for the second 

 cervical nerve. Before these notches are the articular processes, which 

 receive the occipital condyles. The second vertebra of the neck is knovrn 

 as epistropheus {ßg. 37). It is remarkable for the depth of its body, from 

 the upper part of which rises a large round dentiform {odontoid) process 

 {ßg. 37 '), the fore part of which is received into the small articulating cavity 

 on the anterior arch of the atlas, while posteriorly it presents a small, smooth 

 convexity, which moves against the smooth surface of the transverse lio-a- 

 ment of the atlas. 



Pi. 123, ßg. 35, the atlas from above: 1. Superior articular surface for 

 the occipital condyles; 2. Posterior, and 3, anterior arch, with their respective 

 tubercles ; 4. Transverse process ; 5. Spinal hole. 



Fig. 36, the atlas from below : 1. Inferior surfaces for articulating with 

 second cervical vertebra ; 2. Articulating surface for the odontoid process 

 of the epistropheus. 



Fig. 37, the second cervical vertebra (epistropheus) from behind : ', 

 the body ; ', odontoid process ; ', superior oblique process ; ', transverse 

 process. Fig. 38, the same from the side : \ body ; ', odontoid process ; 

 ', superior oblique process or articulating surface ; ', transverse process ; 

 '", spinous process. 



Fig. 39. A cervical vertebra from above : '' \ body ; \ transverse pro- 

 cess; *, oblique process; \ arch; ", spinous process. 



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