496 



TEXTBOOK OF ZOOLOGY 



Muscular System 



The muscles of the body are divided into segmental myotomes with 

 intervening connective tissue sheets or myosepta. A horizontal septum 

 along the side of the body divides the muscles into a dorsal, epaxial 

 portion and a ventral hypaxial portion. The principal sets of super- 



Fig. 271, B, — Left lateral view of the muscles of the head and shoulder re- 

 gion of the salamander, Nectiirus maculosis, (From Atwood, Comparative Yerte- 

 brate Dissection, The Blakiston Company.) 



i— ~ ~ rectus abdominis 



myotomes '• 



pectineus 

 I _^ pubofemoralis -■ 

 ■p internus '^ 



ischiofemoralis— "" 



rectus exteraus 



■-gracilis • *- - 



- pubotibialis 

 femorofibulariS:- - 



- ischiocaudalis'' 



gluteeus maxim us 

 _/— - semimembranosus 

 pyrifonnis— '' 

 flexor commimis - 

 extensor communis 



Fig. 271, C — The muscles of the hind legs of Necturus maculosus ; ventral view 

 on the left, dorsal view on the right. In the dorsal view tlie ilium has been cut 

 from the pelvic girdle and deflected downward. 1, 2, and 3 are extensors of the 

 foot, and 4 is a flexor. (From Atwood, Comparative Vertebrate Dissection, The 

 Blakiston Company.) 



