Chap. V. The Anatomy of a HORSE. 55 



but efpccially to Beads of Burden, being a Bar and Stay 

 to the whole Back. 



The Par quadrat urn ^ or fecond Pair, fo called from 

 their Figure, being fquare when join'd together, tho' tri- 

 angular when feparaie. They arife broad, thick, and 

 flefliy from the backward and upper Cavity of the Haunch- 

 tone, and from the inner and upper Side of the Os Sacrum^ 

 and are inferted into all the tranfverfe Procefles of the 

 Vertebra of the Loins. Their Ufe is to bend the Racks 

 of the Loins with a right Motion forward or downward, 

 but when one only ads, it draws the Loins to one Side 

 fomewhat downwards. 



The third Pair, arifing from the Os Sacrum^ are there- 

 fore called Par facrum ; they fpring from that Part of 

 the faid Bone where the Spine is faften'd, ending in the 

 Spine of the loweft Vertebra of the Thorax ; but at the 

 fame time having in their Paflage feveral Infertions into 

 divers of the Spines and oblique Procefles of the Vertehrcs 

 of the Loins. If thefe a6l feparately, they pull the Body 

 a little on one Side ; but when both a<n: together, they ex- 

 tend that Part of the Spine to which they are faften*d. 



The lall Pair, call'd Semifpinatumy arife with a nervous 

 Original from all the Spines or Ridges of the Os Sacrum 

 and Loins, and are inferted into the tran veffe Procefles of 

 the Loins, and fome of the lowermofl: of the Chefl:. When 

 all thefe Mufcles of the Back and Loins work together, the 

 whole Back is extended ; but if the Mufcles of that Side 

 alone, the Body is then inclined to that Side. 



The Alius hath three Mufcles, two call'd The Anus thm 

 the Levators, and one nam'd its Sphin^er, Mufcles. 



The Sph'm^er isfeated at the Extremity j « , . „ 

 of the ftreight Gut, encompafllng it all ^ ^ *" ^^* 

 round like a Ring. It is attach'd to the lower Vertebra 

 of the Os Sacrum., compofed of circular Fibres, being of 

 ufe to contrad the Orifice of ^ that Gut, as has been ob- 

 ferv'd in another Place. 



The two Levators^ or Lifters up of the ^^ t'vjo Leva- 

 Fundament, are fmall, broad, and nervous, f°^^* 

 arifing from the Ligament of the Hip-bones and Os Sa- 

 cruwy from whence, pafling by the Sides of the Gut, 

 they adhere to it, and are inferted into the upper Part 

 of the Sphinder ; a Portion of them alfo growing to the 

 Root of the Yard, and in Mares to the Neck gf the Ma- 

 trix, Their Ufe Is to aflift the Mufcles of the lower Belly 



