THE MUSCULATURE OF THE TRUNK. 279 



to, and its relative position defined in describing 

 the last muscle. In Figs 66 and 67, I find that I 

 can indicate only the principal origins and insertions 

 of these less important muscles of the back, as an 

 injury would be done the drawings, and its general 

 clearness interfered with, if all the smaller origins and 

 insertions were given, together with the necessary 

 lines to indicate them. 



The present muscle has quite a complicated origin, 

 though its insertion is rather simple. It arises from 

 the inner moiety of the anterior margin of the ilium, 

 and from the various surfaces afforded it by the walls 

 of the corresponding " ilio-neural canal," or that channel 

 existing between the ilium and the crista of the sacrum 

 in front. In some specimens I have seen the posterior 

 tendinous ends of the longissimus dorsi extend beyond 

 the hinder opening of this channel, and in some cases 

 almost reach the superior caudal muscles. Of course, 

 in Eeptiles, the muscle is continuous the entire length 

 of the back and tail, to the very tip of the latter. 



In our subject the longissimus dorsi also arises by 

 a series of short and distinct tendons alternately from 

 the anterior and posterior extremities of the summits 

 of the neural spines of all the dorsal vertebra3. 

 It will be remembered that the free margins of these 

 neural spines above are l^ifurcated behind and pointed 

 in front. Now the tendons of this series attached to 

 the points in front extend forwards and merge into 

 the muscle, and are tendons of insertion, while those 



Opisthotenar (Tnnerer Bauch). Meckel, System, p. 291, No. 1. 

 Longissimus dorsi. Giirlt, p. 18 ; Owen. 



,, „ Selenka, p. 94, No. 2. 



„ „ Watson, p. 56. 



Long du dos. Gervais et Alix, p. 13." 



