DISSECTION OP THE DOG 73 



ilio-hypogastrio nerve. The artery pierces the transverse abdominal muscle, 

 and is mainly expended between this and the internal oblique muscle. Col- 

 lateral branches are contributed to the fat about the kidney, the adrenal 

 gland, and the sublumbar muscles. 



It will be observed that the phrenico-abdominal artery crosses the dorsal 

 face of the adrenal gland, while the corresponding vein occupies a groove 

 on the ventral face of the gland. 



A. EENALis. — The renal artery is relatively large. The right and left arteries 

 do not always leave the aorta at the same level. The right artery generally 

 arises before the left, and crosses the dorsal face of the caudal vena cava. The 

 renal artery soon disappears into the hilus of the kidney. 



A. SPERMATICA INTERNA. — The internal spermatic artery is small and takes 

 origin from the aorta at a variable point cranial to the caudal mesenteric 

 artery. After an oblique course within a fold of peritoneum which also contains 

 the corresponding vein, the spermatic artery enters the inguinal canal and there 

 forms one of the constituents of the spermatic cord. 



The corresponding artery of the female (a. ovarica) supplies the ovary, the 

 uterine tube, and the extremity of the uterine cornu. 



Aa. lumbales. — The lumbar arteries arise in pairs from the dorsal side of the 

 aorta. In all there are seven pairs, but the last springs from the hypogastric 

 artery and not from the aorta direct. Each artery disappears almost at once 

 under the psoas muscles, and therefore cannot be followed at present. 



A. ciRCTTMFLEXA ILIUM PEOEimDA. — The deep circumflex iliac artery 

 leaves the aorta at a right angle. Having crossed the psoas muscles and come 

 into company with the lateral cutaneous femoral nerve, the artery becomes 

 subcutaneous in the region of the angle of the ilium. Its terminal branches are 

 distributed superficially over the cranial aspect of the thigh and the adjacent 

 part of the abdominal wall. 



In cleaning the origin of the circumflex iliac artery, a group of lymph- 

 glands will be observed lying along the side of the aorta. 



Vena cava caudalis. — This large vein begins at the seventh lumbar 

 vertebra slightly to the right of the median plane, where it is formed by the 

 union of the two common iliac veins which drain the limbs and the pelvis. 

 The vessel runs along the right side of the aorta for some distance ; but the 

 right lumbar part of the diaphragm ultimately separates the vein from the 

 artery. The last part of the abdominal course of the vena cava is between the 

 diaphragm and the liver. Thus the vein reaches the foramen venae cavse of the 

 diaphragm, and, by it, enters the thorax. 



The tributaries of the caudal vena cava are as follows : (1) Cotnmon iliac 

 veins (vv. ihacee communes) ; (2) lumbar veins, six or seven (vv. lumbales) ; 

 (3) circumflex iliac veins (vv. circumflexse ilium profundse) ; (4) spermatic veins 

 (vv. spermaticse) — the left may join the renal vein of that side instead of opening 

 into the vena cava directly ; (5) renal veins (vv. renales) ; (6) phrenico-abdominal 



