132 MUSCULAR SYSTEM. 



detach any lateral slips, until it has descended to near the middle 

 of the coccyx. Its fleshy belly, on the whole, is more bulky than 

 that of the erector ; it grows contracted in passing out of the 

 pelvis, but afterwards forms a rounded prominence along the 

 under part of the tail. Its posterior attachments are made by 

 strong and detached tendons, issuing from the broad one travers- 

 ing its middle, which are concealed within the fleshy belly. Its 

 tendons increase in number, but diminish in size, as the muscle 

 proceeds backward : near the tip of the tail, they surpass in 

 strength those of the erector. It is the principal one of these 

 tendons which commonly project within the section made in the 

 operation of nicking, and requires excision. 



Action.— -To depress the tail and retain it against the rump. 

 If one muscle act alone, it will at the same time incline the tail 

 to one side ; in which case it may co-operate with the erector of 

 the same side. The power of action possessed by the depressors 

 may be roughly estimated, by the force it requires with the hand 

 to raise the docks of horses that are said to be " shy about the 

 tail." 



cuRVATOR coccYGis. — Sacfo-cocci/geus lateralis. 



Situation. — Upon the side of the dock, between the two former. 



Form. — Smaller than either of the afore-described muscles ; 

 though it bears a close similarity to them in the appearance and 

 disposition of its fibres. 



Attachment. — Anteriorly, within the pelvis, to the lateral parts 

 of the sacrum; and, commonly, to the fourth and fifth lumbar 

 vertebrae ; posteriorly, to the transverse processes of all the bones 

 of the coccyx. 



Relations. — Superiorly, with the erector ; inferiorly, with the 

 depressor ; externally, with the skin ; internally, with the coccyx. 



Structure. — Anteriorly, it consists of two parts, which have 

 been regarded as separate muscles : one portion accompanies the 

 erector ; the other the depressor. Posteriorly, it consists of ten- 

 dinous and fleshy parts intimately and inseparably interwoven 

 with each other. 



Action. — -To curve or flex the tail laterally around the quarter. 

 In switching off" flies from the hind parts, these muscles are the 

 principal ones called into action. 



COMPRESSOR COCCYGIS. — Ischio-coccygeus. 



Situation. — At the side of the root of the tail. 



Form. — Broad and flattened. 



Attachment. — Anteriorly, to the sacro-sciatic ligament and to 



