534 



LABORATORY MANUAL OF HUMAN ANATOMY 



and coccygeal nerves. Supplement the dissection by use of 

 models and moist preparations. Compare the arrangement of 

 the muscles in the two sexes. Study comparative preparations 

 of the dog pelvis from the museum, and note how homologous 

 muscles are related to the tail. 



(a) Levator ani muscle ("elevator muscle of the anus") (M. levator ani). 



(aa) Pubococcygeus muscle (M. pubococcygeus). 



(ab) Iliococcygeus muscle (M. iliococcygeus). 



(b) Coccygeus muscle (M. coccygeus). 



Are the anterior and posterior sacrococcygeus muscles present in your 

 subject? 



FIG. 287. 



M. sacrococcygeus anterior 



Aponeurosis of the pars pubica of 

 the M. levator ani 



M. coccygeus 

 M. rectococcygeus 



. Vertebra sacralis II. 

 Lig. sacrotuberosum 



sacrococcygeum anterius 

 M. obturator interims 

 Fascia obturatoria 



\Canalis obtuatorius 

 Intestinum rectum 

 Rarm 



Arcus tendineus 

 M. levatoris ani 



M. levator ( Parsillaca 

 ani \Pars pubica 



The levator ani and coccygeus muscles, seen from above. The hip-bones have been pulled apart after 

 splitting the symphysis ossium pubis. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 514, Fig. 891.) 



Pelvic Spinal Nerves. (Vide Toldt, Fig. 1295.) 



Determine the number of nerves entering into the formation 

 of each of the following plexuses. Are the plexuses formed by 

 the anterior or posterior primary divisions of spinal nerves! 

 Trace each nerve as far as possible, noting course and distribu- 

 tion. Make a drawing of the plexuses and determine the gen- 

 eral plan of their formation. 



(a) Sacral plexus (plexus sacralis). 



(aa) Superior gluteal nerve (N. glutaeus superior). 



(ab) Inferior gluteal nerve (N. glutaeus inferior). 



