8 ANATOMY OF THE HORSE. 



oily to their middles, through which run the vertebral arteries ; 

 two through their anterior parts, one of which is directed out- 

 wards and downwards, the other runs inward and opens into 

 the vertebral canal : the latter give exit to the sub-occipital 

 nerves. The anterior articular processes are represented by four 

 horizontal projections, with semicircular borders, whose internal 

 surfaces are smooth, look towards each other, and together 

 form two lateral concavities for the reception of the condyles 

 of the occipital bone. The posterior articular processes are 

 formed into broad, triangular, convex, smooth surfaces, looking 

 backwards, with an inclination inwards. 



The Second Vertebra, or axis, also denominated the den- 

 tata (from a peculiar projection anteriorly, which in the human 

 subject is resembled to a tooth) is the largest of the cervical class, 

 exceeding the others however more in length than in breadth. 

 The body is elongated, and (in place of a hemi-spherical termi- 

 nation) anteriorly, presents the remarkable process named the 

 odontoid, which is smooth and convex below, where it articu- 

 lates with the infero-posterior part of the ring of the atlas ; ex- 

 cavated and impressed above by the odontoid ligaments. The 

 spinous process is very broad, and forms an elevated crest, 

 bifid posteriorly. In front of the body are two oval foramina, 

 corresponding to the holes of conjugation. The transverse pro- 

 cesses are slender, and have only posterior extremities ; the 

 holes through them are also small. The anterior articular pro- 

 cess are represented by two broad ovoid smooth surfaces ; unit- 

 ed with the sides of the odontoid projection; and sloped off 

 backwards, both above and below, to admit of free motion be- 

 tween them and the posterior articular surfaces of the atlas. 



The Third, Fourth, and Fifth possess the genuine cha- 

 racters of cervical vertebrse, and closely resemble one another ; 

 the third however has commonly a more elevated superior spine 

 than either of the others, and is narrower across the mesio- 

 superior part of the body, measuring from the roots of the arti- 

 cular processes : which dimension increases in the fourth, but is 

 greatest in the fifth. 



The Sixth has no inferior spine; and its transverse pro- 

 cesses are trifid, consisting each of three eminences. 



The Seventh Cervical Vertebra is the shortest, and 

 in its general conformation partakes of the character of the 

 first dorsal. Its body posteriorly presents two semilunar arti- 

 cular hollows for the formation of the sockets for the ribs. The 

 superior spine is elevated and sharp. The transverse processes 

 are short, obtuse, and not perforated. 



