AN ANOMALY OF THE THORACIC DUCT. 49 



midline ventral to the aorta, at the level of the ninth intervertebral disk, to become the 



chief tributary of the azygos. (Fig. 3, conn, v.) In fact, this branch is larger than the 

 posterior continuation of the azygos itself, which is about 4 mm. in diameter. The azygos 

 narrows rapidly below the point of junction of this branch, receiving branches from the 

 tenth and eleventh intercostal and the subcostal spaces. A narrow vessel runs from the end 

 of the azygos, across the body of the twelfth vertebra, dorsal to the aorta, and anastomoses 

 with one of the left subcostal veins. 



The vein mentioned, which runs from the left renal vein to join the left azygos, courses 

 on the bodies of the vertebrae to the left of the aorta, and dorsal to the left renal arteries. It 

 has a minimum diameter of about 2.7 mm. 



Associated with this variation in the azygos veins is one of the left renal vein. This, 

 instead of crossing the midline to the inferior vena cava, runs posteriorly, joining the vena 

 cava at its origin opposite the angle formed by the two iliac veins. In addition to its con- 

 nection with the inferior portion of the hemiazygos, the renal receives, as usual, the adrenal 

 and ovarian veins. 1 The right renal vein is not abnormal. 



To return to the lymphatics, it may be said at once that the abdominal and pelvic 

 viscera, the intercostal spaces posterior to the ninth, and both posterior extremities are 

 drained by lymphatics which collect into the left subcutaneous duct already described. 

 (Figs. 2 and 3.) Following this duct backwards, it is found that, after passing superficial 

 to the ligamentum inguinale, it runs posteriorly as far as the junction of the great saphenous 

 vein with the femoral vein. It winds around the saphenous, as this vein passes through 

 the deep fascia to join the femoral, and starts anteriorly along with the deep vessels. It 

 soon divides, smaller branches passing superficial to the external iliac vessels, and running 

 to the iliac lymph nodes which surround the external iliac vessels. The largest branch 

 passes anteriorly at first medial to the external iliac vessels. A little above the ligamentum 

 inguinale it winds around behind (dorsal to) the iliac vessels, until it lies lateral to the 

 anterior third of the common iliac artery and vein. Here it divides into several branches, 

 which pass in part to the more anterior iliac lymph nodes, in part anteriorly along the left 

 of the aorta to the left lumbar nodes, and in part ventral to the aorta to drain directly the 

 plexus surrounding the superior mesenteric artery and celiac axis. 



The lymphatics, draining the abdominal and pelvic viscera and legs, reach the duct 

 as follows: Several ducts from the left inguinal nodes join the main duct and its branches 

 both before and after it curves around the saphenous vein. Others pass under the ligamen- 

 tum inguinale to the lowest external iliac nodes. The lymph from the right leg, after pass- 

 ing through the right iliac nodes, is carried by a number of ducts, some of which run across 

 the front of the sacrum and the last lumbar vertebra to the left iliac nodes, while others 

 pass anteriorly on all sides of the iliac vessels, the lateral ones running to the right lumbar 

 nodes, the ventral and medial ones running in part to a large node which lies ventral to the 

 aorta just before its division, whose efferents pass to the left iliac nodes and in part dorsal 

 to the aorta and vena cava, curving to the left and entering the left inferior lumbar nodes 

 and the anterior iliac nodes. From the pelvic viscera ducts pass to the right and left iliac 

 nodes, the right nodes being drained by the ducts already described. 



The abdominal lymphatics present an interesting condition. There is no definite 

 receptaculum chyli, nor are there any especially widened vessels in the region where the 

 receptaculum is usually found. Instead there are plexuses and numerous narrow vessels 

 lying dorsal to the aorta and vena cava inferior on the bodies of the last thoracic and all 



'It should, perhaps, be noted that a double ureter is present on the left side; the left kidney is considerably longer. 

 slightly narrower, but nearly twice as thick as the right, so that as a whole it is decidedly larger than the right. 



