THE MUSCULATURE OF THE TRUNK. 303 



145. The obliquus interims abdominis 1 is exposed 

 after we have completely removed the external oblique. 



It arises aponeurotic from the hinder third of the 

 post-pubic element of the pelvis ; and by fleshy 

 fibres from the remaining part of this bone ; and 

 occasionally by a few fibres from the iliac border beyond 

 the acetabulum. From this line of origin the fibres of 

 the internal oblique pass longitudinally over the abdo- 

 men to the thorax, where they become inserted into 

 the entire posterior margin of the last vertebral rib, 

 and into the pleurapophysial head of the last costal 

 rib ; which latter, as we know, is a floating one, and 

 articulates with this last vertebral rib. 



The mesial margin of this muscle is free, and does 

 not blend with the rectus abdominis, as Professor 

 Owen states that it does in the Kiwi-kiwi, nor do we 

 have the slightest difficulty in the Eaven in dis- 

 tinffuishinfir this muscle from the ultimate intercostal 



S iD 



muscle, as that eminent authority also found to be 

 the case in his subject. 



146. The rectus abdominis, 2 on either side, arises 



1 From the same source from which we obtained the synonymy of 

 the external oblique muscle of the abdomen, we have the following 

 (p. 127):- 



" 20. M. OBLIQUUS ABPOMINIS INTERNUS. 



Tertium par musculorum abdominis. Aldrovandi. 



M. obliquus interior. Steno. 



Le petit oblique. Vicq d'Azyr, p. 267, No. 2 ; Cuvier, p. 324 ; 

 Gervais et Alix, p. 16 ; Alix, p. 387. 



M. oblique ascendens. Merrern, p. 151, No. 3. 



M. obHquus internus abdominis. Wiedemann, p. 80 ; Tiedemann, 

 230 ; Owen, Apteryx, p. 286 ; Magnus, p. 231 ; Selenka, 

 p. 103, No. 26; Gadow, No. 4; Watson, p. 73. 



Innerer schiefer Bauchmuskel. Meckel, System, p. 303, No. 2." 



2 Following the synonymy of the muscles in Aves as given by 



