MUSCULAR SYSTEM 611 
M. caudslioflexorius or semitendinosus, subject to many modifica- 
tions, but when fully developed, as in Gallinx, arising from the 
transverse processes of the first three caudal vertebre 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 
ee A 
Lerr TuicH-Muscies (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; JI. fb. m. ilio-fibularis (cut away); JI. tib. m. ilio-tibialis 
(cut away); Js. fl. m. ischio-flexorius ; Is. fm. m. ischio-femoralis; P.i.f. m. pub-ischio- 
femoralis ; Sart. m. sartorius; N, nerve. 
angle jois 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 Phew or confined to the intercondyloid region. 
In almost all swimming Birds as well as in some of the Picariz, 
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 Gallinex, Pteroeles, 
