PARTICULAR VERTEBRAE 



181 



single 



Fig. 283. Cervical Vertebra 



1 Articular Head. - Vertebral Foramen. 3 Transverse Pro- 

 cess. 4 Spinal Canal. * Anterior Articular Process. 6 In- 

 ferior Spinous Process. 



convexities or condyles (occi- 

 pital condyles) at the back of 

 the head. It is by the peculiar 

 construction of this joint that 

 the free up-and-down move- 

 ment of the head upon the 

 neck is rendered possible. 



Behind is a large 

 articular surface with which it 

 is united to the second bone 

 or axis. The spinal opening in 

 this bone is of considerable size, 

 in order to permit the exten- 

 sive and varied movements of 

 the head upon the neck with- 

 out injury to the spinal cord. 



The Axis (fig. 3, Plate XXXVIII) or second bone of the neck is so 

 called because it serves as a pivot on which the head is moved from 

 side to side. The pivot is provided by a pro- 

 cess of bone (odontoid process) which proceeds 

 from the anterior extremity of the body and 

 passes into the ring of the atlas which is in front 

 of it. This bone differs from the other cervical 

 vertebrae, in the large size and strength of its 

 superior spinous process, the small size of the 

 transverse processes, and the presence of only 

 two oblique processes, which are behind. 



The remaining five cervical vertebrae are dis- 

 tinguished numerically as the 3rd, 4th, 5th, 6th, 

 and 7th (fig. 283), and although each possesses 

 some minor distinctive feature, it is not neces- 

 sary to dwell upon them here. 



The Dorsal Vertebrae (fig. 284) present 



a good deal in common. Some of them, how- 

 ever, are readily distinguishable from the others 

 by the length of the superior spinous processes. 

 This is especially the case with regard to the 

 first eight bones. Of these the length in- 

 creases to the fifth, and then gradually diminishes backward. 



The Lumbar Vertebrae (fig. 285) are distinguished from those above 

 described in the much greater length and width of their transverse pro- 



Fig. 284. Dorsal Vertebra (Front 

 View) 



1 Superior Spinous Process. 

 2 Transverse Process. 3 Articula- 

 tion for Tubercle of Rib. 4 Articu- 

 lation for Head of Rib. 5 Anterior 

 Articular Face of Body. 8 Spinal 

 Canal. 



