THE POSTERIOR VENA CAVA. 625 



the suspensory ligament, at the inner side of the principal interosseous 

 plantar artery. Near the tarsus, it receives a very large branch from the 

 external vein, and then traverses the cuboido-cuneo-scaphoid canal, to form 

 the largest root of the anterior tibial vein. 



8. Veins of the Digital Begion. 



As these resemble, in every respect, those belonging to the anterior 

 limb, the same description will suffice for both (see page 613). 



DIFFEREKTIAL CHARACTERS IN THE VEINS OF OTHER THAN SOLIPED ANIMALS. 



It does not come -within our plan to give a complete history of the venous system of 

 these animals, because of the small utility of such a study. To remain faithful to the 

 object in view, we confine ourselves to the indication of the special characters of the 

 veins on which bleeding is usually practised, and those which may be interesting in a 

 surgical point of view, as the digital veins of Ruminants. 



A. Angular Vein of the Kye. — This vessel is remarkable for its large volume in 

 the Slieep ; and as it is well defined beneatli the skin, in consequence of the fineness of 

 that membrane, it is more frequently selected for phlebotomy than in other animals. 



B. Jugular Vein. — ^Very large m all animals, and particularly in the Ox, this vein 

 deserves the preference given to it when it is proposed to abstract a certain quantity of 

 blood from the system. 



In all non-soliped animals there is found an accessory jugular, which sometimes exists 

 in the Horse, but is much less in size, alongside the common carotid artery. It arises 

 from the occipital vein, and, therefore, measures the whole length of the neck. Sometimes 

 its diameter is small ; but it is often so large as to receive a very notable quantity of 

 blood from the principal jugular, when compression is applied to the latter to favour the 

 flow of blood after opening it : a circumstance which explains the difficulty sometimes 

 experienced in obtaining a voluminous jet of blood. 



C. Abdominal Subcutaneous Vein. — In the Bovine species, this vessel has an 

 enormous volume, especially in the milch-cow, in contradistinction to the subcutaneous 

 thoracic vein, which is always very narrow. 



This vein is prolonged forward on the wall of the abdomen, to nearly the xiphoid 

 cartilage, where it passes thi-ough to join the internal thoracic vein.' Behind, it is 

 formed by multiple branches, which anastomose with each other, or with those of tue 

 opposite vein, and are in communication with the proper external pudic veins. 



D. Internal Saphena Vein. — This is alway smaller than in holipeds, and is rarely 

 SGlPctfiQ. to dIggq. frowi 



E. External Saphena Vein.— This vessel is, on the contrary, more voluminous than 

 in the Horse, and at the same time more superficial ; consequently, it is more favoura,bly 

 situated for phlebotomy, as well in Pigs and the Carnivora, as in Ruminants. It arises 

 from the union, in the hollow of the hock, of the two principal roots furnished by the 

 metatarsal veins. 



F. Veins of the Posterior Foot in the Ox. — As in the Horse, they commence m 

 the subungueal network of the digital region, which is double, like the region itself. 



a. Three digital veins leave this reticulum : 1, A median or anterior one, arising by 

 two roots from the anterior part of each network, passing between the two dlglt:^, and 

 joining the anterior superficial metatarsal vein above the fetlock ; 2, Two laterals, com- 

 municating with one another, behind, by a transverse anastomosis which receives several 

 venules from the ungueal plexus, and with the anterior vein by an interdigital branch, 

 united by an arch in front of the flexor tendons, above the sesamoid groove. 



6. These digital veins are continued by five metatarsal veins : two deep and one 

 superficial anterior, and two posterior. 



The two deep anterior veins are small vessels which accompany the collateral artery 

 of the cannon, which is placed between them. They arise in the interdigital space from 

 the anterior digital vein, communicating, by the inferior metatarsal foramen, with the 

 sesamoid arch, sending off on their way transverse anastomoses, and bemg continued 

 above the tarsus by the two anterior tibial veins, whose roots they constitute. _ 



The anterior superficial vein is very voluminous. It proceeds from the sesamoid arch, 



1 The openings through which these vessels pass in the abdominal parietes, are 

 commonly named the milk fountains or doors. 



