THE MUSCLES OF THE LOWER EXTREMITY. 179 



and designed to show the origin and insertion of a number of the 

 muscles of the hind limb. J.2).i.p.p., flexor perforatus indicts primus 

 pedis. 



FIG. 50. Sketch of anterior aspect of the head of the tibia of the same specimen, 

 enlarged ; showing insertions of the muscles there found. 1, the 

 extensor fcmoris ; 2, peroncus longus ; 3, tibialis anticus (inner head) ; 

 4, extensor longus digitorum ; 5, separate slip from extensor longus 

 digitorum. 



behind the muscular contour of the thigh. It arises 

 from the hinder third of k the postacetabular ridge, and 

 by a thin, though strong, fascia from the surface of the 

 caudal muscles beneath it. Its fibres pass obliquely 

 downwards and forwards to become inserted into the 

 tendinous raphe which is found along the posterior 

 truncate margin of the accessory semitendinosus, the 

 lower point of which raphe merges with the median 

 fascia of the inner head of the gastrocnemius muscle. 



So far as I can ascertain from anatomical works at 

 present available, the origin of the semitendinosus in 

 the Eaven seems to be, at least, quite an uncommon one. 

 Owen, speaking of it for the Apteryx says, it " arises 

 from the posterior and outer part of the sacrum and the 

 aponeurosis connecting it with the ischium;" while Forbes, 

 describing it more generally for the class, says that " it 

 arises from the transverse process of the first free coc- 

 cygeal vertebra, and from the fibrous membrane between 

 this and the ilium." Indeed, we have yet much to 

 investigate in the myology of this group of vertebrates ! 



101. The accessory semitendinosus is a Hat oblong 

 muscle that arises from an oblique line just above the 

 condyles, on the posterior aspect of the shaft of the 

 femur (Fig. 46). Its fibres, passing directly upwards 

 and backwards, attach themselves to the tendinous raphe 

 common to this muscle and the semitendinosus, already 

 described in the preceding paragraph. 



In the Raven the accessory semitendinosus has a 



x 2 



