374 



THE ANATOMY OF THE HORSE. 



of the tail there are three muscles, viz., one above, one below, and one 

 at the side. There are also three arteries — one on the middle line 

 below, and one between the inferior and lateral muscles on each side. 

 On each side there are two sets of nerves, one of which accompanies the ■ 

 lateral artery, while the other is on the iipper aspect of the bones, 

 between the lateral and superior muscles. [Besides the three muscles 

 now to be described, there is the compressor cocoygis already dissected 

 (page 355)] 



The Erector Cogcygis (sacro-coccygeus superior). This muscle arises 

 from the sides and summits of the sacral spines, and it is inserted by 

 successive short tendons to the upper aspect of the coccygeal vertebrae. 



Action. — Acting with its fellow, to elevate the tail directly ; acting 

 alone, to elevate the tail and incline it laterally. 







Fig. 54. 

 Muscles ok the Tail, deep Muscles of the Hip, and Pelvic Ligaments (Cliauveau). 



1. Erector coocygis ; 2. Ourvator coccygis ; 3. Depressor coccygis ; 4. Compressor cocoygis; 

 5. Deep gluteus ; 6. Rectus parvus ; 7. Common tendon of obturator internus and pyriformis ; 

 8. Gemelli ; 9. Accessory fasciculus of the same ; 10. Quadratus femoris ; 11. Sacro-sciatic ligament ; 

 12. Great sacro-sciatic foramen ; 13. Superior ilio-sacral ligament ; 14. Infeiior ilio-sacral ligament. 



The CuRVATOR Cocoygis (sacro-coccygeus lateralis). This muscle 

 seems to continue backwards the semispinalis of the loins. It arises 

 from the last two lumbar spines and from the spines of the sacrum, 

 and it is inserted into the lateral aspect of the coccygeal bones. 



Action. — To bend the tail to the side of the acting muscle. 



The Depressor Cocoygis. Anteriorly this muscle consists of an 

 outer and an inner portion, which Leyh describes as separate muscles. 

 It arises from the lower face of the sacrum, beginning about the 3rd 

 foramen. The slips of the inner portion are inserted into the first six 



