34 SKETCH OF THE ANATOMY OF THE HORSE. 



beyond the position occupied by the head when the horse is asleep 

 standing, has to be obtained by muscular force. This ligament is popularly 

 called the packtvax. Without being pedantic, we might, I think, more 

 appropriately term it the suspensory ligament of the head and neck. I may add 

 that it is continuous with the strong, white fibrous ligament which commences 

 on the spine of the sacrum and runs along the top of the spines of the 

 vertebrae of the loins and back, binding them together, until it nearly reaches 

 the summit of the withers, where its fibres assume the character of yellow 

 elastic tissue. On the top of this large ligament there is a layer of fat, which 

 in entires (especially if they be coarsely bred) often increases to a great size, 

 and consequently gives them a high and thick crest {see PI. 30). The 

 intestines of the horse are supported by the abdominal tunic, which covers the 

 muscles of the lower part of the belly, and consists of a broad, strong sheet 

 of yellow elastic tissue. It acts like an elastic abdominal belt. 



There is considerable power of movement between the head and the first 

 vertebra of the neck (the altas), and between the different neck vertebrce 

 themselves ; but there is hardly any play between the dorsai vertebrce. 

 The loin vertebrcz can be flexed and extended to a limited degree on each 

 other ; but are capable of only very slight motion from side to side. The 

 sacrum, as before mentioned, forms a single bone, on which the pelvis rests, 

 and with which it is connected by powerful ligaments that greatly restrict its 

 movements on the spine. We have also seen that the thigh bones articulate 

 with the pelvis. The bones of the tail possess considerable mobility. The 

 solid connection thus afforded to the hind limbs, with the trunk, enables the 

 former to transmit to the latter the forward impetus given during progression 

 with the least possible loss of power. The capability of the loins to be flexed 

 and^ extended is necessary in order to facilitate the action of the loin muscles, 

 which are important agents in locomotion {see p. 64). The mobility of the 

 head, neck, and, to a much lesser degree, of the tail, acting as they do 

 as balancing poles, is extremely useful in enabling the animal to perform 

 with ease and precision many of the varied and difiicult movements 

 demanded of him. W' e may see that any power of lateral motion which the 

 trunk (not counting the head, neck and tail) may possess, however much it 

 may make the horse quick and "handy" at turning, will militate against his 

 speed in a forward direction. 



The respective ends of the first eight ribs form movable joints with the 

 spine and breast bone ; the first articulating with the last neck vertebra and 

 first dorsal vertebra ; the second ^\'ith the first and second dorsal vertebrae, 

 and so on. 'iliey are rigidly connected to their cartilages, of which those of 



