. The American journal of anatomy. andthe left intercostal arteriespass dorsad on the right sideof the vein. The manner in which thecaudal end of the azygos veinjoins the postcava was found tobe quite variable. It may jointhe postcava to the left, whichis the usual method, or to theright of the aorta; or it maybifurcate into two branches onthe ventral circumference ofthe aorta, one of Avhich joinsthe postcava to the right andthe other to the left of theaorta. In the latter case the;iorta is encircled by a venousring formed by the azygos andpostcaval veins. On account of the numerousvariations
. The American journal of anatomy. andthe left intercostal arteriespass dorsad on the right sideof the vein. The manner in which thecaudal end of the azygos veinjoins the postcava was found tobe quite variable. It may jointhe postcava to the left, whichis the usual method, or to theright of the aorta; or it maybifurcate into two branches onthe ventral circumference ofthe aorta, one of Avhich joinsthe postcava to the right andthe other to the left of theaorta. In the latter case the;iorta is encircled by a venousring formed by the azygos andpostcaval veins. On account of the numerousvariations which occur in thecranial part of the thoracicregion it is difficult to estab-lish what might be called atypical arrangement of thetributaries of the azygos arrangement, however,which comes nearest to beingtypical is represented by TextFig. IV. Here all of theintercostal spaces on bothsides, except the first two, are drained by the azygos system; also theblood from the lumbar region, on the left side, as far eaudad as the. ,RXin Fig. IV. A diagram representing the usual ar-rangement of the azygos branches in Didelphysmarsupialis. Ventral view. cL, clavicle ; d. and e., tributaries of the \ . cos-tovertebralis; do., dorsal portion of venous ringabout clavicle; g., second intercostal vein; pc,postcava; pre, precava; K., rib; S., intercostalspace; v., ventral portion of venous ring aboutclavicle; V. V. azygos; , V^. anastomotica , V. costovertebralis; , V. Intercostalis;,V. jugularis externa; V. lumbalis; V. r.,; , V. subclavia; , V. vertehralis. Charles F. W. McClure 383 third, and, on the right side, as far caudad as the second lumbar ver-tebra, is collected by the tributaries of this vein. The blood from therest of the lumbar region is collected by the lumbar veins which openinto the postcava. The blood from the first intercostal space is col-lected, on both sides, by the superficial superior intercostal vein(V. i. s. I,
Size: 999px × 2502px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectanatomy, bookyear1901
