THE EXTERNAL ILIAC ARTERIES. 



637 



Fig. 371, 



Origin. — The digital arteries succeed the termiual extremity of the collateral 

 of the cannon, and separate from one another in forming an acute angle below 

 the sesamoidean venous arch, 

 above the fetlock-joint, between 

 the two branches of the sus- 

 pensory ligament, behind the 

 inferior extremity of the large 

 metatarsal bone, and in front 

 of the flexor tendons of the 

 phalanges. 



Course and Relations'. — These 

 vessels descend — one to the 

 right, the other to the left, from 

 the lateral parts of the metacar- 

 po-phalangeal (and metatarso- 

 fhalaiKjml) articulation to the 

 internal face of the basilar pro- 

 cess, where they bifurcate to 

 form the plantar and preplantar 

 ungual arteries. 



"In the whole of this course, 

 it (the digital artery) follows the 

 track of the flexor tendons, rest- 

 ing on their margins, and main- 

 tained there by loose connective 

 tissue. Behind, it is flanked by 

 the plantar nerve, which covers 

 a portion of its surface, enlaces 

 it v\'ith numerous filaments, and 

 is so closely associated with it 

 in all its flexuosities, as to form 

 but a single cord with it. 



" In front, it is margined, 

 though for a short distance, by 

 its satellite vein, which for the 

 whole of its track rests on the 

 lateral faces of the two first 

 phalanges. 



"At its upper part, near 

 its origin, and on the lateral 



PRINCIPAL ARTERIES IX THE POS- 

 TERIOR FOOT OF THE HORSE. 



1, Anterior tibial artery ; 2, pedal or 

 great metatarsal artery; 3, meta- 

 taiso-pedal or perforating meta- 

 tarsal ; 4, arteria pedis perforaas ; 



5, 5, digital arteries ; 6, 6, arterioles of the ergot ; 7, perpendicular artery ; 8, artery of the plantar 

 cushion ; 9, anterior branch of the coronary circle ; 10, circumflex artery of the coronary cushion ; 

 11, preplanter ungual artery; 12, inferior circumflex arterv of the foot; 13. collateral branch of 

 the posterior tibial artery distributed to the external surface of the hock ; U, arteriole furnished 

 by the arch formed by the union of the two plantar arteries with the arteria pedis perforans, across 

 the superior extremity of the supensory ligament of the fetlocli. 

 43 



