SUPERIOR VENA CAVA, WITH ITS FORMATIVE BRANCHES. 339 



side of the foot and leg. It passes Behind the outer ankle, ascends 

 along the posterior aspect of the leg, lying in the groove between 

 the two bellies of the gastrocnemius muscle, and pierces the deep 

 fascia in the popliteal region to join the popliteal vein. It receives 

 several cutaneous branches in the popliteal region before passing 

 through the deep fascia, and is accompanied in its course by the 

 external saphenous nerve. 



The Internal saphenous vein commences upon the dorsum and 

 inner side of the foot. It ascends in front of the inner ankle, and 

 along the inner side of the leg ; it then passes behind the inner con- 

 dyle of the femur, and along the inner side of the thigh to the saphe- 

 nous opening, where it pierces the sheath of the femoral vessels, 

 and terminates in the femoral vein, at about one inch and a half 

 below Poupart's ligament. 



It receives in its course the cutaneous veins of the leg and thigh, 

 and communicates freely with the deep veins. At the saphenous 

 opening it is joined by the superficial epigastric and circumflexa ilii 

 veins, and by the external pudic. The situation of this vein in the 

 thigh is not unfrequently occupied by two or even three trunks of 

 nearly equal size. 



VEINS OF THE TRUNK. 



The veins of the trunk may be divided into 1. The superior vena 

 cava, with its formative branches. 2. The inferior vena cava, with 

 its formative branches. 3. The azygos veins. 4. The vertebral 

 and spinal veins. 5. The cardiac veins. 6. The portal vein. 7. 

 The pulmonary veins. 



SUPERIOR VENA CAVA, WITH ITS FORMATIVE BRANCHES. 



Vence Innominate. 



The Vena innominatce are two large trunks, formed by the union 

 of the internal jugular and subclavian vein, at each side of the root 

 of the neck. 



The Right vena innominata, about an inch and a quarter in length, lies 

 superficially and externally to the arteria innominata, and descends 

 almost vertically, to unite with its fellow of the opposite side in the 

 formation of the superior cava. At the junction of the jugular and 

 subclavian veins it receives from behind the ductus lymphaticus 

 dexter, and lower down it has opening into it the right vertebral, 

 right internal mammary, and right inferior thyroid vein. 



The Left vena innominata, considerably longer than the right, ex- 

 tends almost horizontally across the roots of the three arteries arising 

 from the arch of the aorta, to the right side of the mediastinum, 

 where it unites with the right vena innominata, to constitute the 

 superior cava. 



