70 



THE MUSCLES. 



Figs. 62, 63), in front of the anterior edge of that muscle. The 

 posterior border of the muscle is uncovered. 



Fig. 64. 



Second layer of abdominal muscles of Rana escuknta, from the right side and below. The 

 m. obliquus externus and tlie right anterior extremity has been removed. 



dm M. depressor maxillae. 



/((/ M. hyoglossus. 



Id M. latissimiis dorsi and infraspinatus. 



ot M. obUquus internus. 



oi' Insertion of third portion of same. 



oi" Second portion inserted into the pharynx. 



pc Pericardium. 



p/i-*. M. petrohyoideus quartus. 



r M. rectus abdominis. 



,is M. sub icapularis. 



The insertions of the muscle are yery various^ and as a conse- 

 quence very various functions are accomplished by it. 



a. The most anterior part of the muscle (Fig. 6q oi'"), the fibres 

 of which run forwards, is attached — 



1. Partly to the xijDhisternum and the coracoid. 



2. A second portion, viz. that arising from the transverse pro- 

 cesses of the fourth vertebra (Fig. 64 oi"), surrounds the pharynx 

 like a diaphragm (Fig. 6^ oe), and is attached to its side as far as 

 the dorsal aspect (Fig. 6^ oi'). This portion is lightly separated 

 from the following, 



3. A third portion, placed behind the preceding, runs from the 

 pharynx over the pericardium (Fig. 64 pc), and is attached to this 

 nearly as far as the middle line (Figs. 64 oi' and 6^ oi"), resting 

 on the sternum, the m. rectus and m. sterno-hyoideus. The lines of 

 insertion of the muscles of 02:)posite sides form an angle, ojien in 

 front. In the thin borders of this portion the muscular bundles lie 

 almost entirely in simple layers, and they are therefore well adapted 

 for microscopical purposes. 



b. The middle and posterior j^ortions of the muscle pass down- 



