THE MUSCLES OF THE LOWER EXTREMITY. 247 



muscles at the back of the tibia (see Figs. 46, 52, 59, 

 60, and others). 



Its highest origin is by a strong, fleshy head from 

 the posterior aspect of the external condyle of the 

 femur. Two other fairly defined heads of this muscle 

 come off from the tibia behind, just below its summit ; 

 the inner one being close to the origin of the soleus. 

 This deep flexor also arises from the major portion of 

 the posterior surface of the tibial shaft (Fig. 52) as 

 well as from the fibula. In form, it is flattened, with 

 a strong fascia covering its exposed or external surface, 

 extending nearly its whole length from the femoral 

 head. At the lower third of the tibia it terminates 



variations the flexor dig. profundus takes on in the various groups 

 of birds (loc. cit., pp. 193-196) : 



" 53a. M. FLEXOE PROFUNDUS S. PEKFORANS. 



M. secundus posterior digitos movens. Aldrovandi. 



M. octavus posterior circa tibiam et fibulam. Steno. 



Le flechisseur perforant. Vicq d'Azyr, p. 284 ; Cuvier, p. 558. 



Zweikopfiger Muskel. Merrein, p. 161. 



Flexor profundus s. perforans trifidus. Wiedemann, p. 104. 



Flexor profundus s. perforus trifldus. Tiedemann, 312. 



Durchbohrender oder tiefer durchbohrender Beuger. Meckel, System, 



p. 386-390, No. 3 ; Archiv, 278-279, No. 5. 

 Flexor profundus s. perforans ; Jlexor communis IV. dig. s. sublimis 



pars post, d' Alton, p. 38. 



Flexor digitorum longus s. perforans. Gurlt, p. 31. 

 Flexor perforans digitorum. Owen, Cyclop., p. 297 ; Apteryx, p. 295 ; 



De Man, p. 130, No. 19 ; Watson, p. 124. 

 Flexor digitorum communis profundus. Quennerstedt, p. 45 ; 



Neander, p. 27. 



Flexor perforans. Reid, p. 144. 

 Flechisseur profond. Gervais et Alix, p. 35. 

 Flechisseur profond, perforant oil commun des trois doigts proprement 



dits. Alix, p. 459. 

 Flexor prof%mdus. Garrod, Proc. Zool. Soc., 1872, p. 363 ; Gadow, 



No. 39." 



