114 DISSECTION OF THE DOG 



itself between the pubis and the internal obturator muscle. Entering the 

 thigh, it hes between the pectineus and adductor muscles. 



N. H^MOBEHOiDALis CAUDAiis. — The Caudal hsemorrhoidal nerve supplies 

 branches to the bladder and rectum. 



A. SACRA MEDIA. — The middle sacral artery arises from the end of the 

 aorta in the angle formed by the two hypogastric arteries, and runs along the 

 mid-ventral line of the sacrum into the tail. 



Pabs abdominalis et pelvina SYSTEMiE SYMPATHici. — The Sympathetic 

 system is continued from the thorax into the abdomen and onwards into 

 the pelvis. The abdominal part is connected with a chain of seven lumbar 

 gangha which will be found deep down in the narrow chink between the 

 two psoas minor muscles. The ganglia have the usual communications with 

 the spinal nerves, and filaments arising from them take part in the formation 

 of an aortic plexus. 



The various plexuses in connection with the abdominal viscera have already 

 been examined. 



After the formation of the seventh lumbar gangUon, the sympathetic cord 

 becomes markedly thinner. The sacral part is feebly developed and runs 

 along the ventral surface of the sacrum immediately dorso-lateral to the 

 middle sacral artery and vein. One or two small ganglia are present. 



The Female Pelvis. — The examination of the female pelvis follows 

 the same lines as those laid down for the pelvis of the male. The first thing 

 to be done is to make a general examination of the disposition of the pelvic 

 organs so far as is possible before any dissection has been carried out. 



The pelvic inlet is occupied by the urinary bladder, the vagina, and a 

 part of the colon. Thus the entrance to the female pelvis contains practically 

 the same organs as are associated with the male cavity, with the addition 

 of the vagina. 



The general form of the bladder agrees with that of the male organ, but 

 there are no deferent ducts associated with its neck. As in the male, the 

 peritoneum is reflected from its mid-ventral and lateral aspects onto the 

 abdominal wall in the form of three membranous sheets. In the female, the 

 peritoneum associated with the bladder does not extend into the pelvis but 

 is reflected ventrally and laterally onto the abdominal wall about the brim 

 of the pelvic inlet. From the dorsal side of the neck of the bladder peritoneum 

 is continued to the vagina. 



The vagina occupies a position dorsal to the bladder and ventral to the 

 termination of the colon. Lateral folds of peritoneum — continuations of the 

 broad ligament of the uterus — connect the vagina with the wall of the cavity. 

 Dorsally the peritoneum is carried back for some distance into a pouch (the 



