152 



INFERIOR OR ASCENDING VENA CAVA. 



smaller of the two, and under it pass branches of the external 

 cutaneous nerve.*'* A branch of the internal cutaneous nerve*^ *' 

 passes oveY the median basilic, and may be cut in bleeding. 



SUPERIOR OR DESCENDING VENA CAVA. 



The veins which are engaged in forming the descending cava* are 

 the right and left vena innominata. 



Riglit Inyiominata^ is about an inch and a quarter in length, and 

 is formed by the junction of the internal jugular^ and subclavian* 

 veins. It is situated at the root of the neck, and descends super- 

 ficially and obliquely in front of the arteria innominata to join its 

 fellow. At this junction it receives the right thoracic duct. 



Left Innominata.'^ — This is much 

 Fig. 134. longer than the right, and is formed in 



the same manner. It receives at its 

 commencement the left thoracic duct. 

 It passes horizontally across the root 

 of the chest, and is frequently called 

 the transverse vein, it joins its fellow 

 to form the descending cava. 



INFERIOR OR ASCENDING 

 VENA CAVA. 



This is formed by the junction of the 

 iliac veins between the fourth and fifth 

 lumbar vertebrae. It ascends^ upon the 

 vertebral column to the right of the 

 aorta, and in its course receives the 

 lumbar, right spermatic, renal, and he- 

 patic veins ; it then passes through the 

 foramen quadratum of the diaphragm, 

 to enter the right auricle of the heart. 



Spermatic veins. — These originate 

 in the vasa pampiniformia. The right^ 

 empties into the ascending cava, and 

 the /<?f^" into the left renal. 



Renal ov emulgent. — These are large 

 and return the blood from the kidney 

 to the ascending cava. The right*^ is 

 much shorter than the left. 



Hcjmtic.^^ — These convey the venous 

 blood from the liver by three large 

 branches, which open at its posterior 

 notch, into the ascending cava. 



