202 THE SURGICAL ANATOMY OF THE HORSE 



follow the course taken by the plantar nerves, in front of which they 

 are placed. These are unnamed arteries. They are long and very 

 slender, and may extend as far as the sesamoid bones and anastomose 

 with collateral branches of the digital arteries. The remaining two 

 branches of the arch are the plantar interosseous arteries. The external 

 plantar interosseous artery descends along the groove between the outer 

 edge of the suspensory ligament and the inner surface of the outer 

 splint bone. It terminates above the fetlock by anastomosing with a 

 recurrent branch of the large metatarsal artery. The internal plantar 

 interosseous artery is a much larger vessel. It descends similarly along 

 the inner edge of the suspensory ligament, and from it the nutrient 

 artery of the large metatarsal bone is derived. Just above the button 

 of the inner splint bone it passes towards the middle of the limb and 

 joins the large metatarsal artery. 



The only point of surgical importance in connection with the four 

 small vessels described is the relation of the two small unnamed arteries 

 to the plantar nerves, and consequently to the seat of operation in 

 plantar neurectomy. 



THE LARGE METATARSAL ARTERY 



This vessel may be regarded as the continuation of the anterior 

 tibial artery, since it is so much the larger of its two terminal branches. 

 From the division of the anterior tibial artery near the entrance to the 

 cuboido-scaphoido-cunean canal this branch inclines obliquely down- 

 wards, outwards and backwards, passing beneath the extensor brevis 

 muscle and the tendon of the peroneus. This part of its course is 

 indicated on the large metatarsal bone by a smooth oblique groove 

 which is placed in the upper fourth of its external lateral surface. The 

 artery then arrives at the channel formed anteriorly between the large 

 and external small metatarsal bones, down which it runs, being here 



