ANATOMY OF THE HORSE. 



LUMBAR VERTEBRA. 



Volume, between that of the cervical and dorsal, — Number, 

 in some subjects five, in others six. Body, short and thick ; 

 flattened superiorly, prominent inferiorly ; and bearing much re- 

 semblance to that of a dorsal, only that it is something larger, 

 is oval from side to side, and thicker anteriorly than posteriorly : 

 its articulatory convexity in front and concavity behind assume 

 also rather an oval than a heart shape. The vertebral hole is 

 simi-circular, and of larger diameter than in the dorsal verte- 

 brae. The spinous process is shorter than most of the dorsal ; 

 has broad flat sides ; protuberates at the front of its summit ; and 

 stands erect with a very slight inclination forwards. The trans- 

 verse processes, stand out horizontally, at right angles from the 

 body, slightly inclined in the form of arches ; are long and 

 broad ; flattened above and below ; and gibbous at their extremi- 

 ties. The articulatory processes, though small when compared 

 with the cervical, are larger than the dorsal; they project from 

 the roof of the arch in the horizontal direction : the anterior, 

 protuberate at their extremities, are wide apart, and present 

 concavities inwards ; the posterior, are nearer together, and pre- 

 sent convexities outwards. The notches are similar to those in 

 the dorsal vertebrae. 



PECULIARITIES OF THE VERTEBRiE. 



Of the cervical, four vertebrae are distinguished by peculiar 

 characters. 



The First Vertebra, inappropriately named the atlas, 

 (for the head is suspended from it instead of being supported by 

 it,) is defective in the essential vertebral properties ; being sim- 

 ply an irregular ring with broad projecting sides. It has no 

 body; the place being in part supplied, in the articulated spine, 

 by the odontoid process of the second vertebra, for the recep- 

 tion of which, the infero-posterior part of the ring is made 

 smooth and articulatory ; this somewhat reduces the dimensions 

 of the vertebral hole, though it remains even then the most ca- 

 pacious of any, and measures more from side to side than con- 

 trariwise : its inferior surface is deeply impressed by the odon- 

 toid ligaments. It has no superior spinous process, but there 

 is a prominence in the situation of it; and the inferior spine is 

 shorter, thicker, and more obtuse than the others. The trans- 

 verse processes are broad undivided lateral plates, sloping 

 downwards, perforated by three pairs of foramina : — one posteri- 



