120 Anatomy of the Rabbit. 



enclose a large aperture, the vertebral foramen (foramen verte- 

 brale). The successive foramina form an almost complete tube, 

 the vertebral canal (canalis vertebralis), for the accommodation 

 of the spinal cord. 



The body of a vertebra is a cylindrical, or somewhat dorso- 

 ventrally compressed, mass of bone, which bears at either end an 

 articular surface for attachment to the adjacent vertebra. The 

 articular surfaces are borne on thin plate-like epiphyses, the epiphy- 

 sial lines being evident even in older animals, especially in the 

 lumbar region. The dorsal portion of the body bears on either side 

 the pedicle, or root of the vertebral arch (radix arcus vertebrae), 

 the dorsal surface of the body forming in this way the floor of the 

 vertebral foramen. The dorsal portion of the arch, borne on the 

 pedicle, is distinguished as the lamina. The anterior and posterior 

 margins of the pedicle are notched, each notch or incisure being 

 converted, through its association with that of the adjacent verte- 

 bra, into a rounded aperture, the intervertebral foramen (fora- 

 men intervertebrale), for the passage outward of a spinal nerve. 



The arch of the vertebra is noteworthy for its projections or 

 processes. On either side is a horizontal plate of bone, the 

 transverse process (processus transversus) , and, dorsally, a 

 median projection, the spinous process (processus spinosus), all 

 three serving for the attachment of the vertebrae to one another 

 by ligaments, and for the attachment of the spinal musculature. 

 Special articular surfaces, borne on low articular processes 

 (processus articulares), are found on the anterior and posterior 

 margins of the arch. The anterior, or superior articular surfaces 

 are directed for the most part toward, the dorsal surface, and. are 

 overlapped in the natural condition by the inferior articular 

 surfaces, which are directed toward the ventral surface. A 

 certain amount of movement is permitted, by one surface slipping 

 across the other, the mechanism illustrating the arthrodia, or 

 gliding-joint. 



The cervical vertebrae (vertebrae cervicales) are sevan in 

 number. The posterior five are similar, while the anterior two are 

 specially modified in relation to the skull. The posterior vertebrae 

 (Fig. 56, C) are dorsoventrally compressed, their arches low, and 

 the spinous process short. In the seventh vertebra, however, the 

 spinous process begins to be elongated as in the succeeding thoracic 



