MUSCULAR SYSTEM OF MAMMALIA. 2& 



anterior part of the bodies and transverse processes of the vertebrae 

 above them, and into the anterior surface of the atlas. 



The muscles which raise or straighten the tail are the 

 following : — - 



The * sacro-coccygeus superior ' arises from the third and suc- 

 ceeding sacral spines, and from those of the anterior caudal vertebrae. 

 The fleshy mass formed from these origins gives off numerous 

 slender tendons : the first of these is the shortest, and runs inward 

 to be inserted into the base of the first caudal vertebra, in which 

 the articular apophyses are wanting. The second tendon is in- 

 serted in a similar manner into the succeeding vertebra ; the third 

 into the next, and so on to the end of the tail. Each tendon is 

 lodged in a sort of ligamentous canal, which forms a sheath for it 

 throughout its whole course. When these two muscles act in 

 concert the tail is raised. 



The * interspinales superiores ' form a continuation of the inter- 

 spinous series of vertebral muscles ; but as the spinous processes 

 of the tail are short, and soon replaced by tubercular rudiments of 

 the neurapophyses, these muscles are here disposed obliquely, being 

 more widely separated posteriorly than they are in front. 



The muscles which depress the tail all take their origin in the 

 interior of the pelvis, and are prolonged to a greater or less extent 

 along the inferior aspect of the tail. They form four pairs of 

 series of muscles, called the ( ileo-coecygei,' and * sacro-coccygei 

 inferiores ; ' the latter are the more direct antagonists of the sacro- 

 ^occygei superiores, and their tendons are received into sheaths 

 resembling those upon the upper surface of the tail, and are 

 inserted successively into the base of each caudal vertebra, begin- 

 ning about the seventh. 



The muscles adapted to move the tail laterally are arranged in 

 two sets ; the ' ischio-coccygei externi,' a few fibres of which, in 

 the Horse, are connected with the termination of the rectum and 

 the ' intertransversales.' 



The muscles derived from the vertebral column which serve im- 

 mediately for the movements of the cranium have nearly the same 

 origins as in the human subject, but are comparatively of much 

 greater strength, owing to the inclined position of the head with 

 respect to that column. They may be divided into such as pro- 

 ceed, 1st, from the atlas ; 2nd, from the axis ; and, 3rd, from the 

 posterior cervical vertebrae and ligamentum nuchae. To the first 

 set belong 



The ' rectus posticus minor,' e rectus anticus,' ( rectus lateralis,' 

 and ' obliquus superior.' 



