DISSECTION OP THE POSTERIOR LIMB. 77 



cutaneous division of the nerve pierces the deep fascia, and passes over 

 the hock to supply the skin on the outer side of the metatarsus. 



The Anterior Tibial Nerve separates from the preceding at an 

 acute angle, and a few inches below the stifle it passes under cover of 

 the extensor pedis. It supplies twigs to the last-named muscle, the 

 flexor metatarsi, and the short extensor ; and descends at the outer side 

 of the tibial vessels, afterwards accompanying the large metatarsal artery 

 to terminate in the skin on the outer side of the digit. 



The Anterior Tibial Artery (Plate 19). This, it will be recol- 

 lected, is one of the terminal branches of the popliteal artery. Origi- 

 nating behind the upper extremity of the tibia, it is here seen coming 

 forwards through the tibio-fibular arch. It descends on the tibia, 

 under cover of the flexor metatarsi, and accompanied by the nerve and 

 vein of the same name. Gaining the front of the hock, it rests on the 

 anterior tibio-tarsal ligament, covered by the flexor metatarsi and 

 extensor pedis at their line of contact. Here it deviates outwards under 

 the tendon of the last-mentioned muscle, and divides into two vessels 

 of unequal size. The larger of these, which continues the direction 

 of the parent vessel, is the large metatarsal artery ; the other is the 

 perforating metatarsal artery ; and both will be dissected with the 

 metatarsus. The anterior tibial artery gives off numerous un-named 

 muscular hranches to the extensor pedis, flexor metatarsi, and peroneus ; 

 and articular branches to the hock. 



The Anterior Tibial Vein, which may be double, keeps close com- ' 

 pany with the artery. It is formed at the front of the hock by 

 the fusion of several rootlets. The largest of these is the upward 

 continuation of the deep metatarsal vein, which comes forwards through 

 the vascular canal between the tarsal bones. After passing backwards 

 through the tibio-fibular arch, the anterior joins the posterior tibial 

 vein to form the popliteal. 



THE metatarsus AND DIGIT. 



The distal portion of the horse's hind limb, beyond the lower extremity 

 of the tibia, is technically termed theses, as it corresponds to the foot 

 of man. The tarsus, or hock, represents the human ankle ; the part 

 between the tarsus and fetlock corresponds to the body of the human 

 foot, -and is termed the metatarsus ; while the rest of the limb, beyond 

 the fetlock, is the digit, and is the homologue of man's third toe. 



Surface-marhing. — Extending down the middle line in front is the 

 tendon of the extensor pedis, which, a little below the tarsus, is joined 

 obliquely by the tendon of the peroneus. Behind the metatarsus, and 

 resting on the bone, is the suspensory ligament ; and behind that 

 again are the deep and superficial flexors of the foot. The edges of 

 these structures can be distinctly seen or felt in the living animal, and 

 jn the dead subject they may be identified by a reference to Plate 19. 



