Muscles of the Leg. 



329 



Os sacrum 

 Ligamentum saerospiuosum j 

 with the m. coccygeus 



M. piriformis 



Os ilium 



Ligamentum 

 sacrotuberosum 



M. obturator 

 interuus 



Tuber 



ischiadicum 



-^Capsula articularis 



Trochanter major 



Crista intertroclianterica 



Troclianter minor 



Femur 



M. obturator externus 



374. Muscles of the small or true pel- 



vis on the right side, viewed from without and below. 



M. obturator externus (see also Figs. 378 380). Form: triangular, thick. Posi- 

 tion: anterior surface of the small pelvis and beneath the hip-joint. Origin: anterior surface 

 of the I is coxae and of the memhrana obturatoria . Insertion: convt^'ging lateral ward ti > the fossa 

 trochanterica femoris. Action: it rotates the thigh outward. Innervation: n. obturatnrius. 



M. piriformis (see also Figs. 373, 385 and 386). Form: Hatly roimded, triangular. 

 Position: behind the hip-joint. Origin: facies pelvina oss. sacri. Insertion: the fibers 

 run, converging, thi-ough the foramen ischiadicum majus lateral ward to the tip of the trochanter 

 major femoris (bursa m. piriformis see Fig. 386). Action: it rotates the thigh outward and 

 I'xtends it somewhat backward and lateralward. Innervation: ranu' musculares plexus sacralis. 



