6 4 



AN INTRODUCTION TO ZOOLOGY 



M. 



I.J. 



S.C. 



M.C. 



In the same way that the arteries fall into three groups, according 

 to the arches from which they spring, so the veins can be considered 

 in groups according to the trunks they ultimately go to form. The 

 veins may be dealt with in the following groups ; those contributing 



to the formation of the 

 pre-caval veins, the 

 renal portal and ante- 

 rior abdominal veins 

 and the hepatic portal 

 s.s __ ^iX ^^Zd i } /~ vein. 



Blood from the 

 tongue and hyoid is 

 collected by the lingual 

 vein that runs parallel 

 with the external ca- 

 rotid artery. The 

 mandibular vein drains 

 the region around the 

 lower jaw and unites 

 with the lingual in the 

 neighbourhood of the 

 carotid " gland " to 

 form the external jugu- 

 lar, a short trunk run- 

 ning towards the heart. 

 Various tributaries 

 from the dorsal side of 

 the head, the eye and 

 the brain unite near 

 the posterior border of 

 the orbit to form an 

 internal jugular vein 

 which passes backwards 

 for a short distance. 

 It is joined by the sub- 

 scapular vein coming 

 from the shoulder and 

 part of the muscles of 



the back, and the common vessel so formed, termed the innominate, 

 also goes directly inwards towards the heart. 



A large vein, the brachial, collects the blood from the fore limb, 

 shortly after leaving which it is confluent with the musculo-cutaneous 

 vein near the shoulder joint. The musculo-cutaneous is a large 

 vein formed by the union of a number of tributaries coming mainly 



FIG. 21. Diagram of venous system excluding 

 pulmonary veins. Rana. 



A.A., anterior abdominal ; B., brachial ; C., cardiac ; 

 D.L., dorso-lumbar ; E.J., external jugular ; F., femoral ; 

 G., genital ; H., hepatic ; H.P., hepatic portal main trunk 

 and branch to left lobe of liver ; H.P'., branch of hepatic 

 portal to right lobe of liver ; I., innominate ; I.J., internal 

 jugular ; L., lingual ; L.Pr., left precaval ; M., mandibular ; 

 M.C., musculo-cutaneous ; P., pelvic ; P.C., post caval ; 

 P.C'., inter-renal portion of post caval ; R., renal ; R.C., 

 ramus communicans iliacus ; R.P., renal portal; R.Pr., 

 right precaval ; S., sciatic ; S.C., sub-clavian ; S.S., sub- 

 scapular ; S.V., sinus venosus. 



