30 ANATOMY OF VERTEBRATES. 



The muscles derived from the axis are the ( rectus posticus 

 major ' and the ( obliquus inferior.' 



The ' complexus ' commences from the prezygapophyses of the 

 third cervical vertebra, continues its origin from all those of 

 the neck below that point, as well as from those of the first 

 dorsal: also by a strong tendon from the transverse processes 

 of the second and third dorsal vertebra? : from these origins it 

 runs forward to be inserted by a strong round tendon into the 

 super-occipital close to its fellow of the opposite side : in this course 

 it is connected by numerous tendinous processes with the ligamen- 

 tum nuchae. 



The ( trachelo-mastoideus ' arises from the oblique processes of 

 the third, fourth, fifth, sixth, and seventh cervical and first dorsal 

 vertebrae, and from the transverse processes of the second and 

 third vertebra? of the back ; it runs forward external to the last- 

 mentioned muscles to be inserted by a strong tendon into the 

 paroccipital. The above muscles are overlapped by the ' splenius 

 capitis,' which, arising by strong tendinous processes from the 

 spinous processes of the two superior dorsal and two last cervical, 

 and also extensively from the ligamentum nuchae, runs forward to 

 be inserted into the transverse processes of the fifth, fourth, and 

 third cervical vertebrae, and into the transverse ridge of the super- 

 occipital. 



The muscles of the ribs and sternum present, in the Horse, a 

 disposition little differing from that of the corresponding muscles 

 in Man : they are the ' scaleni,' the i intercostals,' the ' levatores 

 costarum,' the ( serratus posticus,' d, and ( serratus anticus,' /, and 

 the e triangularis sterni,' the two latter of which must be regarded 

 as depressors of the ribs, and consequently acting the part of 

 muscles of expiration. 



The walls of the abdomen are composed of five pairs of muscles, 

 to which the same names are applicable as are bestowed upon 

 them by the anthropotomist ; but the rectus abdominis is much 

 more extensively developed. Arising from the os pubis, it passes 

 forward enclosed in its usual sheath to be inserted into the ensi- 

 form cartilage and into the cartilaginous terminations of the 

 third, fourth, fifth, sixth, seventh, eighth, and ninth ribs, and 

 also into the sternum between the cartilages of the third and 

 fourth ribs. There are even fleshy fibres derived from this 

 muscle prolonged as far forward as the articulation between the 

 first rib and the sternum. 



Muscles of the anterior extremity. The * trapezius ' consists 



