678 BLOOD-VASCULAE SYSTEM OF THE HORSE 



and anastomoses with a branch of the posterior femoral artery. In some cases an 

 arch is formed by junction with the peroneal artery on the lateral surface of the deep 

 flexor at the distal fourth of the leg. 



The medial tarsal artery (A. tarsea medialis) usually forms a double curve in 

 front of the tuber calcis, then descends on the deep flexor tendon with the plantar 

 nerves, and divides into the two plantar arteries. From the second part of the 

 curve there arises a small branch, the recurrent tibial artery (A. tibialis recurrens). 

 This ascends along the medial border of the superficial digital flexor in company 

 with a satellite vein and the tibial nerve, and anastomoses with a descending branch 

 of the posterior femoral artery and with the saphenous artery. ^ 



6. The plantar arteries, medial and lateral (A. plantaris medialis, lateralis), 

 are the small terminals of the- medial tarsal. They descend along the sides of the 

 tarsal sheath of the deep flexor tendon with the plantar nerves to the proximal part 

 of the metatarsus, where they unite with the perforating tarsal artery to form the 

 proximal plantar arch (Arcus plantaris proximalis). Four plantar metatarsal 

 arteries proceed from this arch. The two slender superficial plantar metatarsal 

 arteries (A. metatarsea plantaris superficialis medialis, lateralis) may be regarded 

 as the continuations of the plantar arteries; they descend on either side of the deep 

 flexor tendon with the plantar nerves, and unite with the corresponding digital 

 artery. The medial one is the smaller; it may give off or connect with the cor- 

 responding dorsal artery. The lateral, larger one usually unites with the lateral 

 digital artery. Both may unite at the distal part of the metatarsus to form a short 

 trunk which joins one of the digital arteries. They supplj^ twigs to the flexor 

 tendons and the skin. The two deep plantar metatarsal arteries (A. metatarsea 

 plantaris profundus medialis, lateralis) descend on the plantar surface of the large 

 metatarsal bone alongside of the corresponding small metatarsal bone and unite 

 near the fetlock with the great metatarsal. The medial artery is the larger of the 

 two and usually appears to be the continuation of the perforating tarsal. It 

 supplies the nutrient artery of the large metatarsal bone. In other cases it is 

 the direct continuation of the medial plantar artery, the lateral artery only uniting 

 with the perforating tarsal. The connection of these vessels with the great meta- 

 tarsal artery forms the distal plantar arch (Arcus plantaris distalis). 



ANTERIOR TIBIAL ARTERY 



The anterior tibial artery (A. tibialis anterior) is much the larger of the two 

 terminal branches of the popliteal. It passes forward through the proximal part of 

 the interosseous space and descends with two satellite veins on the lateral part of 

 the front of the tibia, under cover of the tibialis anterior. At the distal part of the 

 leg it deviates to the lateral border of the tendon of this muscle, passes on to the 

 capsule of the hock joint, gives off the large perforating tarsal artery, and is con- 

 tinued as the great metatarsal artery.^ It gives off muscular branches to the dorso- 

 lateral group of muscles of the leg and articular branches to the hock. The per- 

 oneal artery (A. peronea) is a variable vessel which descends along the fibula under 

 cover of the lateral extensor; it gives off muscular branches and one which per- 

 forates the fascia and divides into ascending and descending cutaneous twigs. ^ 



The perforating tarsal artery (A. tarsea perforans) arises under cover of the 

 lateral tendon of the peroneus tertius. It passes backward through the vascular 

 canal of the tarsus with a satellite vein and nerve and unites on the upper part of 



1 The artery may be double in part or throughout. It may join the popliteal artery. The 

 S-shaped curve may be absent and the medial tarsal be the direct continuation of the recurrent 

 tibial artery. 



2 The part of the arterial trunk which is on the dorsal surface of the tarsus may be distinguished 

 by the term A. dorsahs pedis. 



* In some cases the peroneal artery is larger than usual and forms an anastomotic arch with 

 the lateral tarsal in the distal part of the leg. 



