76 THE ANATOMY OF THE HORSE. 



function being to confer strength (for which purpose they 

 are very short, and very closely locked together), and to 

 permit of the motion of the ribs. 



The bones of the loins have more motion, particularly 

 the last, which is rather loosely articulated with the first 

 bone of the sacrum. This gives to the horse a facility of 

 rearing up ; an act which he could never perform, were the 

 last lumbar vertebrae as firmly fixed as most of the other 

 bones of the spinal column. 



The spinal column serves to hold and to safely lodge the 

 spinal marrow, there being holes in the sides of the bones 

 which admit of the passage of the spinal nerves. The bones 

 already referred to are termed true vertebrae, because they 

 have all the processes and uses belonging to the most perfect 

 of these bones. The rest, to be mentioned hereafter, are 

 termed false, because one or more of the processes are 

 wanted, and their functions are limited. 



The top of the pelvis, or the sacrum {Skel. 6, 6, 6, 6, 6), 

 is in the very young foal composed of five pieces of bone ; 

 but long before the animal becomes an adult the bones are 

 united, and the whole then consists of one piece. In this 

 latter view we choose here to regard it as one bone ; for 

 there are other bones in the body, the pieces of which are 

 not united till after the sacrum, and yet by anatomists these 

 last are considered to form one bone. The sacrum, then, 

 which constitutes a continuation of the spine, is composed 

 of irregular vertebree, because the spinal marrow does not 

 descend so far as this bone, but only nerves travel along its 

 internal canal ; because it is gifted with less motion than 

 true vertebrae, and because also it is deficient in some of 

 the processes and articulations. 



We said it had less motion. It has no lateral motion, 

 though it is able to be elevated at its front part consider- 

 ably ; and for this reason forms a true synovial joint with 

 the haunch bone. 



The haunch bone, or rump bone, or basin, or pelvis, 

 named ossa innominata (Skel. E), is said to be formed of 

 six bones, for the like cause as the sacrum is said to con- 

 sist of five. We here, however, choose to regard it as one. 

 It is one solid piece, of almost a circular form ; but open 

 before and behind, and at the top, into which last place the 



