OF THE MUSCLES. 37 



number of bundles of fibres interlacing with each other, 

 and terminating in tendons. These fasciculi proceed 

 from the transverse apophyses, and often send tendons to 

 the spinous apophyses ; they are strictly connected with 

 other muscular bundles, which unite the ribs by tens, and 

 are carried forward to the sides of the head. The spaces 

 between the vertebral processes are filled by the spinales 

 and inter- trans versales muscles. The muscles of the ribs 

 are numerous and complicated : some are intended to ad- 

 just the levers, uniting them in fours ; others in a perpen- 

 dicular direction, are also intended as levators of the ribs ; 

 others are seen proceeding equally from the ribs, and de- 

 scending on the skin of the flanks, even to the abdomen ; 

 they cover the fasciculi which are directed obliquely back- 

 wards to unite the ribs by twos, and which form posteri- 

 orly the flexor of the tail. We distinguish, besides, two or 

 three pairs of intercostal muscles, the external layers of 

 which unite the ribs, sometimes by two and two, at other 

 times by four and four. The interior surface of the ribs, 

 and the inferior surface of the vertebras, present several 

 well developed muscles, arising partly from the sides of 

 the vertebrae, partly from the ribs themselves, and inserted 

 into the ribs, either at their middle, or at their sternal ex- 

 tremity : these muscles are intended to depress the ribs, 

 and to draw them backwards ; they stretch under the 

 tail, forming the flexor of that member ; but they are 

 replaced below the neck by the depressors of the head, 

 which have the form of an acute triangle, and are accom- 

 panied by the muscles producing the lateral movements of 

 the head. 



The head itself has many other muscles which take their 

 origin from the posterior spinous processes of the vertebrae 

 of the neck ; one of them extends along the lower jaw, 

 another shorter one passes from the cervical vertebra to the 

 articulation of the jaw. The costo-maxillary muscle ex- 

 tends from the anterior ribs under the throat, to be at- 

 tached to the branches of the lower jaw, the ends of which 

 are bound together by a little transverse muscle. The 

 muscles of mastication are well developed ; the temporal 

 is constantly divided into two parts, of which the anterior 



