THE MUSCULATUEE OF THE TRUNK. 301 



are inserted into the posterior margin of the rib next 

 succeeding and anterior to it in any individual case. 

 With the first pair, these membranes are inserted on 

 the margins of the ribs nearly as high up as the 

 vertebral column, but grow shorter as we near the 

 pelvic extremity of the trunk. 



144. The obliquus externus abdaminis 1 is, as its name 

 implies, the most external of the layer of abdominal 

 muscles, and at the same time it is by far the most 

 extensive. 



It arises by a delicate aponeurotic membrane from 

 the sides of all the true dorsal ribs, on a line drawn 

 at about the bases of their epipleural appendages ; by 

 an extension of the same membrane from the hinder 

 margin of the last vertebral rib, and the adjoining 

 margins of the pelvis ; by fleshy fibres from the entire 

 posterior moiety of the inferior border of the post- 

 pubic element of the pelvis ; and, finally, again as- 

 suming the aponeurotic character, shades off from the 

 structures lying about the root of the tail, and lower 

 part of the abdomen. 



The aponeurotic membrane coming off from all 



1 Most authors have described this muscle under this name, as 

 may be seen by the following synonymy (Gadow, loc. cit., pp. 126, 

 127):- 



" 19. M. OBLIQUUS ABDOMINIS EXTERNUS. 



M. oblique descendens. Aldrovandi. 



M. obliquus exterior. Steno. 



Le grand oblique. Vicq d'Azyr, p. 267, No. 1 ; Cuvier, p. 234 ; 



Gervais et Alix, p. 17. 



M. oblique descendens. Merrem, p. 151, No. 2. 

 M. obliquus externus abdominis. Wiedernann, p. 79 ; Tiedemann, 



229; Owen, Apteryx, p. 286; Selenka, p. 102, No. 25; 



Magnus, p. 230 ; Gadow, No. 1 ; Watson, p. 72. 

 Auesserer schiefer Bauchmuskel. Meckel, System, p. 303, No. 1 ; 



Archiv, p. 249, No. 21." 



