THE MUSCLES OF THE LOWER EXTREMITY. 247 



muscles at tlie 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 

 w^ell 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 



variatioQS the ^flexor dig. jwofundus takes on in the various groups 

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



"53a. M. FLEXOR PROFUNDUS S. PERFORANS. 



M. secundus j)osterior digitos movens. Aldrovandi. 



M. octavus 2Josterior circa tibiam et fihulcmi. Steno. 



Le Jlechisseur 2^6'Kfo'>'(i'fi't ■ Vicq d'Azyr, p. 284; Cuvier, p. 558. 



Zweikopfiger Muskel. Merrem, p. 161. 



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



Flexor profundus s. perforus trifidus. Tiedemann, § 312. 



Durchbohrender oder tiefer durchbohrender Beuger. Meckel, System, 



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

 Flexor profmdus s. perforans ; flexor communis IV. dig. s. suhlimis 



pars post, d' Alton, p. 38. 

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

 Flexor perforans digitorum. Owen, Cyclop., p. 297 ; Aptcryx, 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 pyrofond, perforant ou commun des trois doigts j)ro])re7nent 



dits. Alix, p. 459. 

 Flexor irrofundus. Garrod, Proc. Zool. Soc, 1872, p. 363 ; Gadow, 



No. 39." 



