CHAPTER XII 



ANATOMY AND USE OF THE HORSE'S TAIL 



631. THE tail consists of a continuation of the 

 spinal column. It consists of vertebrae, muscles, 

 ligaments, blood vessels, nerves, fascia, skin and 

 hair. There are fifteen to twenty coccygeal verte- 

 brae, which decrease in size until the last two 

 or three are quite small, round, and resemble 

 somewhat a spindle. The first four or five are 

 very similar to the sacral vertebrae. They con- 

 tain a body, superior or spinous processes, called 

 spines, and a transverse process projecting from 

 each side of the body. The muscles, which lie 

 along the outside of these vertebrae on all sides, 

 are eight in number. There are four pairs, and 

 a bundle of muscles on both sides that reach 

 from one transverse process to the next, called 

 inter-transversales caudae, which help to keep the 

 bones together or, singly, to assist in curving the 

 tail. 



632. The eight muscles are : two above (erec- 

 tor coccygis), that raise the tail, or, acting singly, 

 help to draw it to one side ; one at each side 

 (curvator coccygie), that carry it to the side ; two 

 underneath (depressor coccygis), that depress the 

 tail, or, acting singly, help to draw it to one 

 side ; and two situated underneath, outside the 

 depressors, i.e. on the inferior outward portion 

 of the tail (the compressor coccygis), which com- 

 press the tail over the perineum, or, acting 

 singly, help to draw it to one side. These are 

 used when the horse compresses his tail with 

 force. 



The erector coccyges have their origin on the 

 last three sacral spines, and their insertion on 

 the first two or three coccygeal spines and the 

 dorsal (upper) surface of all the coccygeal 

 vertebra. 



The curvator coccyges have their origin on the 

 sides of the sacral spines and the transverse pro- 

 cesses of the sacral and coccygeal vertebrae. 



The depressor coccyges have their origin on 

 the ventral (under) surface of the posterior parts 

 of the sacrum, and their insertion on the ventral 

 surface of the transverse processes and of the 

 bodies of the coccygeal vertebrae. 



The compressor coccyges have their origin on 

 the large sacro-sciatic ligament inside the pelvic 

 cavity, and their insertion on the ventral surface 

 of the first four coccygeal vertebrae. 



The tail also contains the superior and inferior 

 coccygeal ligaments, which run along the dorsal 



and ventral surfaces of the tail respectively, and 

 the intercoccygeal ligaments, which join the 

 bodies of the vertebrae together. These latter are 

 thick and elastic, to allow the tail to bend into 

 fairly sharp curves. 



633. There are three arteries that supply 

 blood to the tail : the two lateral coccygeal 

 arteries, which are a continuation of the lateral 

 sacral artery (these divide into two, the superior 

 branch passing down between the erector coccy- 

 gis and the transversalis, and the inferior branch 

 between the transversalis and the depressor 

 coccygis (P. 106), each supplying twigs to the 

 muscles and skin), and the middle coccygeal 

 artery, which either arises from the lateral 

 coccygeal or from the right or left lateral sacral 

 (I have seen it arise more often from the lateral 

 coccygeal), and is not paired ; it passes down the 

 inferior surface of the tail between the two 

 depressor muscles. 



634. There are five pairs of coccygeal nerves, 

 five dorsal and five ventral. These unite, form- 

 ing two trunks on either side, which pass down 

 the tail. The superior trunk accompanies the 

 superior lateral artery, and the inferior trunk 

 accompanies the inferior lateral coccygeal artery. 

 These four trunks extend to the tip of the 

 tail, and give off the muscular and cutaneous 

 nerves. 



635. The Panniculus Carnosus. The panni- 

 culus carnosus, or fly muscle, is a muscular 

 layer, varying greatly in thickness, from a very 

 thin, pale muscle over the face to a thick, dark 

 muscle of two inches in thickness over the breast, 

 which extends over most of the body, neck and 

 head, under the skin. It is very closely attached 

 to the skin, and only attached in a very few 

 places to bones, the most important attachment 

 being on the inner surface of the arm bone 

 (humerus). 



It is divided into facial (head), cervical (neck), 

 thoracic (chest) and abdominal (belly). 



The facial portion extends over the sides of 

 the jaws, the submaxillary space (between the 

 lower jaws), and reaches to the mouth. 



The cervical originates in a thick muscle at 

 the anterior end of the breastbone, and extends 

 over the sides of the neck and becomes embedded 

 in the levator humeri muscle, which runs up the 

 side of the neck. The panniculus carnosus does 



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