MUSCULAR SYSTEM 



611 



M. caud-ilio-flexorius or semitendinosus, subject to many modifica- 

 tions, but when fully developed, as in Gallinte, arising from the 

 transverse processes of the first three caudal vertebrae and the 

 lateral margin of the posterior half of the post-acetabular ilium, and 

 thence extending, as a broad ribbon, mesially from the ischiadic nerve 

 towards the popliteal region, where it splits into two portions, one 

 of which, being broad and fleshy, is inserted on the posterior face 

 of the distal third of the femur, while the other starting at a right 



art. 



II til}. 



LEFT THIGH-MUSCLES (Grus or Rallus). Outer view after removal of the superficial m. ilio- 

 fibularis and m. ilio-tibialis. 



A, caudal, B, iliac portion of m. caud-ilio-femoralis ; X, m. caud-ilio-flexorius ; Y, accessory 

 or femoral portion of the same ; II. fb. m. ilio-fibularis (cut away) ; II, tib. m. ilio-tibialis 

 (cut away) ; Is. fl. m. ischio-flexorius ; Is. fin. m. ischio-femoralis ; P.i.f. m. pub-ischio- 

 feinoralis ; Sart. m. sartorius ; N, nerve. 



angle joins the fascia of the inner femoral head of the m. gastro- 

 cnemius. The divergence of these two portions is marked by a 

 tendinous intersection, which running in the direction of the 

 gastrocnemial insertion has caused the femoral portion of the whole 

 to be wrongly described as the "accessory semitendinosus." The 

 extent of the insertion on the femur varies much, occupying more 

 than its distal half in Rliea or confined to the intercondyloid region. 

 In almost all swimming Birds as well as in some of the Picarix, 

 there is a complete split between the femoral and crural portions, 

 the crural tendon being then inserted on the neck of the tibia, and 

 the original femoral portion forming part of the median femoral 

 head of the m. gastrocnemius, in which case the " accessory head " is 

 generally stated to be absent. The origin of this muscle likewise 

 varies, arising either from the tail and ilium as in Galling Pterocles, 



