280 



PRACTICAL ANATOMY. 



branch of the internal iliac artery. Find the groove between this muscle and 

 the psoas, containing the anterior crural nerve. 



Dissection of Sacral Plexus (Figs. 193 and 194). Cut through the symphysis 

 pubis and pull outward on both pubic bones, and separate the ilium from the 

 sacrum, at the sacro-iliac synchondrosis. Then study the following points : 



1. The plexus is located on the posterior pelvic wall. 



2. It rests on the pyriformis muscle. 



FROM LAST THORACIC 



GENITO-CR URA L 



ILIO-HYPOGASTRIC 



ILIO-INGUINAL 



EXTERNAL 

 CUTANEOUS 



OBTURATOR 



A CCESSOR Y 

 OBTURA TOR 



BRANCH TO ILIACUS 

 ANTERIOR CRURAL 



SUPERIOR GLUTEAL 

 INFERIOR GLUTEAL 



GREAT SCIATIC 



NERVE TO 



qUADRATUS 



FEMORIS 



EXTERNAL 



POPLITEAL 



SECTION 



INTERNAL 

 POPLITEAL 



SM'TION 



FIRST L I'M HA R 



SECOND L UMBA R 



THIRD LUMBAR 



FO UR TH L UMBA R 



, FIFTH LUMBAR 



FIRST SACRAL 



SECOND SACRAL 



THIRD SACRAL 



VISCERAL 

 Fornril SACRAL 



PERFORA 77 v; 



i -i y.i.\7:or.v 

 PERIN.KAL 

 FIFTH SACRAL 



NEKVK TO I'OfCYHKl-f! 



NER VE TO LEVA TOR 

 AN! 



FIRST COCCYCI-AL 



VISCERAL 



TO HAMSTRINGS 



SMA LL SCI A TIC P UDIC 



NERVE TO OBTURATOR INTERN US 



FIG. 193. DIAGRAM OF THE LUMBAR AND SACRAL PLEXUSES. Modified from Taterson. 



3. It is covered by the pelvic fascia and peritoneum. 



4. It is crossed by the internal iliac vessels. 



5. The gluteal and sciatic arteries transfix it. 



6. It receives the fifth and part of the fourth lumbar nerves. 



7. The part received from the lumbar is called the lutnbo-sacmil cord. 



8. The tacral [>lc.\ v/.v is formed by the union of the lumbo-sacral cord and 

 the anterior primary divisions of the first, second, third, and a part of the fourth 

 sacral nerves. 





