THE MUSCLES OF THE LOWER EXTEEMITY. 157 



becomes much thicker and bulkier as it descends down- 

 wards and backwards towards the knee, its anterior 

 margin forming the free edge that bounds the group of 

 thigh-muscles in this reejion. 



It is inserted, rather obliquely, by a semitendinous 

 fascia into the inner edge of the ligamentum patellae, and 

 by a somewhat stronger attachment to the inner and 

 contiguous border of the summit of the tibia for its 

 anterior half. 



The sartorius is one of the extensors of the leg, it also 

 flexes and to some extent adducts the thio-h. 



"We find the sartorius muscle (Fig. 62 his) power- 

 fully developed in Geococcyx, as are the majority of the 

 muscles of the thigh in that bird. It arises, semiten- 

 dinous, from the crest of the neural spine of the last 

 vertebra of the dorsal region of the spine, from the 

 summit of the anterior portion of the crista of the 

 sacrum, and from the adjacent surface of the superior 

 aspect of the ilium on the corresponding side. The 

 fibres, forming an oblong and rather thick muscle, 

 pass downwards and backwards to the region in front 

 of the knee. Here it becomes inserted by a special 

 slip of fascia that is thrown oft' and merges with 

 the general fascia surrounding the knee-joint ; and, 

 secondly, by a more carneous insertion into the inner 

 half of the superior rim of the cnemial crest of the 

 tibia and the continuous inner margin of the summit 

 of that bone. 



" The sartorius in this bird bounds anteriorly the 

 superficial group of muscles of the thigh ; consequently 

 its anterior border is free. Its posterior border above 

 unites quite intimately with the overlapping gluteus 

 primus muscle ; while this border below is sharp and 

 free, although here, too, the gluteus also overlaps it. 



