132 THE HORSE 



it is lodged, forms a very protective shelter to it ; never- 

 theless, in spite of this fact, the spinal cord is occasionally 

 implicated in disease. 



Reverting to the structure of the skeleton, the bones of 

 the neck are followed by eighteen dorsal vertebrae, each 

 of which has a well-developed spine on its upper surface, to 

 which ligamentous and muscular structures are attached. 

 The spines are longest at the withers, the summit of which 

 they form. Following the vertebrae last named are those 

 of the loins, called the lumbar vertebrae, of which there are 

 six or seven. Succeeding these are the five sacral vertebrae, 

 which assist in forming the bond of union between the 

 latter, the pelvis, and the hind limbs. Following the sacral 

 vertebrae are the bones of the tail (coccygeal vertebrae). 



The whole of the vertebrae possess limited movement, 

 and the spinal column is a fairly flexible rod, but this 

 degree of flexibility is much greater in some horses than 

 in others owing to the special nature of the work required 

 of them. The ribs number eighteen pairs, eight of which 

 are regarded as true ribs and the remaining ten as false. 

 The first-named are joined on to corresponding segments 

 on the sternum or breast-bone. The last-named forms 

 the floor of the chest. 



Each rib possesses a certain amount of elasticity, 

 consequently these structures are able to resist, without 

 injury, a good deal of external violence, though of course 

 fracture of the ribs in the horse is not in the least un- 

 common. The ribs form the lateral boundaries of the 

 chest wall and part of the roof of the cavity, being assisted 

 in the latter by the bodies of the dorsal vertebras. 



The fore limbs are not attached to the skeleton as in 

 the case of the hind limbs, being m_erely slung on to the 

 body through the medium of muscular tissue, the skin 

 and sub-cutaneous tissue. 



The hind limbs are attached to the spinal column by the 

 pelvic girdle, therefore there is a greater degree of mobility 

 in the fore hmbs of a horse than in the hind ones, no 



