. The biology of the amphibia. Amphibians. THE MUSCULAR SYSTEM 251 muscle fibers of frogs have practically given up their original function of lateral bending but have assumed new functions of holding up the head in leaping and of bending the body sharply upward in a so-called " warning" attitude (Chap. XVI). Although both urodeles and Salientia have very short necks, many species are capable of bringing the head to a lateral position nearly at right angles to the main axis of the body. Such a movement is facilitated by a division of the anterior part of the M. dor salts trunci into
. The biology of the amphibia. Amphibians. THE MUSCULAR SYSTEM 251 muscle fibers of frogs have practically given up their original function of lateral bending but have assumed new functions of holding up the head in leaping and of bending the body sharply upward in a so-called " warning" attitude (Chap. XVI). Although both urodeles and Salientia have very short necks, many species are capable of bringing the head to a lateral position nearly at right angles to the main axis of the body. Such a movement is facilitated by a division of the anterior part of the M. dor salts trunci into several muscle bundles which. R. /V B C D Fig. 92.—A comparison of the ventral body musculature of various Amphibia. Schematic cross-sections through the middle of the body. A. Triturus, larva. B. Triturus, adult. C. Salamandra, adult. D. Rana, adult. , back musculature; , M. obliquus externus abdominis; , M. obliquus exter- nus profundus; , M. obliquus externus superficialis; , M. obliquus internus; , M. pectoralis; R., M. rectus abdominis; , rectus lateralis; , rectus profundus; , rectus superficialis; , subvertebralis; Tr., transversus. {After Maurer.) extend to the skull. In the newt there are three of these mus- cle heads, an apparent fourth being the temporalis, a visceral jaw muscle which extends to the neural spine of the first verte- bra of many urodeles and is especially well developed in the species of Desmognathus. The hypaxial musculature of the early urodele larva approaches the condition in fish. Myocommata are present and the fibers instead of running longitudinally, as assumed for the primitive vertebrate, are arranged into two layers of oblique fibers, the outer running ventroposteriorly and the inner, dorsoanteriorly, that is, in the opposite direction. These are the Mm. obliquus. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration
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Keywords: ., bookcentury1900, bookpublishernewyorkmcgr, booksubjectamphibians
