THE SPINE. 23 



anterior face lias the two articulating condyloid surfaces, six inches long 

 and four across ; the excavation is moderately deep. 



The spinous process is short and notched ; the transverse are very 

 large, strong, and rough on their outer edges. The roots of the latter 

 processes are perforated with holes, about an inch in diameter, for the 

 passage of the vertebral arteries : these apertures open into a canal, which, 

 after running three inches, terminates in another canal leading into the 

 back part of the spinal cavity, and giving passage to the artery already 

 mentioned. The inferior articulating surface is excavated for the reception 

 and interlocking of the superior surface of the second vertebra. The atlas 

 measures eighteen inches across, and thirteen from above downwards; in 

 circumference it is forty-four inches. 



The second vertebra (Plate XXI. Figs. 5, 6, and 7) is of an oblong form, second 



Vertebra. 



and has its longest diameter in a direction from before backwards, and 

 from below upwards. The body is flattened, and surmounted by the odontoid 

 process. The transverse processes are very short and notched ; the spinous 

 process is very large, thick, strong, and rough, affording space for the attach- 

 ment of large and strong muscles. From the superior part of the body 

 arises the odontoid process, which has not the form of that of the human 

 skeleton, but is more pyramidal, solid, and short, extending into the pos- 

 terior face of the body of the atlas. 



The bodies of the third, fourth, fifth, and sixth vertebras present nothing Thud, 



Fourth, 



very remarkable. The spinous processes of these four are very short, being Fifth, 



I'-i-ii in an< ^ Sixth. 



only Irom two to three inches long ; the transverse processes are also short, 

 and are all perforated by the vertebral arteries. 



The seventh cervical vertebra measures fifteen inches across ; the body seventh. 

 is rounded, being seven inches in diameter, and presents on its sides quite 



