THE HEAD AND NECK. 147 



The neck joins the front end of the thorax or 

 chest, the skeleton of which is formed by the dorsal or 

 thoracic vertebrae above, the sternum or breast-bone 

 below, connected together by the hoop-like ribs. As 

 seen in the figure (Frontispiece), the cervical or neck 

 vertebras are flat above, but those of the thoracic 

 region have long processes projecting upwards, and 

 forming together the ridge of the middle of the back. 

 Those of the third, fourth, and fifth vertebras, which 

 are situated between the shoulder-blades, are the 

 longest, and correspond externally to the " withers," 

 the highest point of a horse's back, across which the 

 measuring-rod is placed when taking his height. 



The upper contour of the neck of the living horse 

 is altogether different from that of the skeleton, the 

 great depression seen in the latter in front of the 

 high spines of the thoracic vertebras being filled up 

 in the middle line by a remarkable structure called 

 the " cervical ligament," and on each side of this by 

 large masses of muscles which raise and turn the 

 head, and above all by the median " crest," a soft, 

 but firm, fibrous, and fatty ridge immediately beneath 

 the skin from which the mane grows. 



The cervical ligament (ligamentum cervicis, Uga- 

 mentum nuchce or "pack wax") which in man is 

 quite rudimentary, as his head, balanced on the top 

 of the vertebral column, requires no special support, 



