THE 



ANATOMY OF YERTEBKATES. 



>i^c 



CHAPTER XXVII. 



MUSCULAR SYSTEM OF MAMMALIA. 



The muscular tissue in the present as in the preceding Vertebrate 

 classes presents the two conditions of striped and unstriped elemen- 

 tary fibres : the striped kind, comprising all the voluntary muscles 

 with those of the heart, are red : deeper coloured in Cetacea and 

 Carnivora than in Ungulata : deeper in the pectoral muscles of 

 Cheiroptera than in those of the legs : paler in the pectorals and 

 other muscles of the fore-legs of the Kangaroo than in the ( psoas ' 

 and those of the hind-legs : palest in some Rodentia. 



§ 1 92. The Diaphragm. — The chief characteristic of mammalian 

 myology is the diaphragm, vol. ii., fig. 139, d, which, as such, is not 

 more completely developed in Man than in the Monotreme. It is 

 the partition between the thoracic and abdominal cavities, fig. 1, 

 vaulted and convex toward the thorax, fig. 2, and consists 

 of carneous and tendinous 

 parts, the latter chiefly in l 



the expanded or aponeuro- 

 tic form. The carneous fas- 

 ciculi are divided into the 

 ( costal ' or greater and the 

 J vertebral ' or smaller mus- 

 cles. The costal portions 

 arise from the ensiform 

 cartilage, and those of the 

 eighth to the twelfth ribs, 

 by fasciculi which inter- 

 digitate with those of the 

 ( transversalis abdominis ' 

 muscle. They ascend and 

 expand, arching and con- 

 verging to be inserted into 



A VOL. III. 



(3 



Human diaphragm ; abdominal surface. 



the external f ligamentum arcuatum,' 



B 



