578 PHILOSOPHICAL TRANSACTIONS. [aNNO 17 10. 



diameter 1 1 inches. The transverse processes are in breadth from above to be- 

 Ipw 2 inches, and in length at their lower part 3 inches. 



The second vertebra has remarkable in it, 1st. A large protuberance called 

 the tooth, which is received by a hole in the former, and serves as an axis on 

 which the head is turned round. This tooth runs forward from the body of the 

 vertebra 1 inches above, and 24- inches below, tapering and terminating in an 

 obtuse point. 2. A large protuberance arising from its upper and middle part, 

 (like the processus spinosus in others, 4 inches from the beginning of the trans- 

 verse processes, 2 inches broad at the top, terminating in two obtuse points, 

 with a sinus larger at the back than the fore part) in the middle. This pro- 

 tuberance inclines forward toward the first vertebra : 3. Its body or back part, 

 and base of the tooth, transversely 44- inches, perpendicularly 4 inches. 4. Two 

 oblique processes, by which it is articulated with those of the following, and 

 between which there are 4 inches. 5. Two transverse processes, each 2 inches 

 long. At its fore part, on each side of the tooth, are two protuberances, which 

 are received by the two hind cavities of the first vertebra. This vertebra is 2 

 inches thick from before to behind, the hole for the spinal marrow 2 inches 

 diameter, those for the cervical artery -i- inch diameter. Between the oblique 

 and extremity of the transverse processes, it is 6 inches. 



The third and fourth vertebrae differ from this, 1st. In their four oblique 

 processes, viz. two by which they are articulated with the preceding, and two 

 with the following, which is common to those of the neck, back and loins, 

 2. In their convex body before, and concave behind, where they are received 

 by, and do receive the preceding and following, which is also common to the 

 other vertebrae. 3. In their eminences at the top (between the oblique pro- 

 cesses) at 4-1- inches distance, between which there is a depression in the third, 

 and a small protuberance in the middle of this depression in the fourth. Their 

 transverse processes are 2 inches broad at the extremity, from which they de- 

 scend obliquely 3 inches, having a protuberance on each side, between which 

 and the body of the preceding vertebra, there proceeds a branch of the cervical 

 artery, which it continues to do from between all the other vertebrae of the 

 neck, till it comes to between the seventh of the neck and first of the back, 

 where it is wholly spent. Between the oblique processes and transverse it is 4 

 inches. The hole for the cervical artery is here oval. The bodies of these 

 vertebrae are thinner below than the former : they are 4 inches in diameter, be- 

 ing of the same dimensions with all the other vertebrae of the spine, till we 

 come to the os sacrum. Those in the neck are more fiat before, and those in 

 the back more protuberant. Besides those sinuses in the inside of the fore- 

 mentioned protuberances in the neck, there is likewise a sinus between the 



