THE LIMB IN SECTION 



39 



arteries. It should be observed, as a matter of considerable surgical 

 importance, that the artery is here quite superficially placed, being 

 immediately subcutaneous, and consequently very much exposed to 

 risk of injury — a risk which is added to by the fact that the vessel 

 is on the outer side of the limb. 



The small metatarsal bones form, also, two grooves posteriorly 

 with the large metatarsal. In each of these grooves a vessel is seen. 

 These vessels are the inner and outer plantar interosseous arteries, 

 which, descending from the tarsal arterial arch, run down on either 

 edge of the suspensory ligament, to terminate in the manner already 

 described. 



Lying on the posterior surface of the large metatarsal bone in the 

 middle line, we find the deep metatarsal vein, which runs up the limb 

 in this position from the venous arch which is formed just above the 

 fetlock. It continues its upward course to the back of the tarsus, when 

 it passes from back to front of the limb through the canal formed 

 between the cuboid, scaphoid and cuneiform magnum. 



The posterior surface of the large metatarsal bone forms, with the 

 inner surfaces of the two small metatarsals, a channel in which the 

 suspensory ligament will be observed to be placed. In the Plate the 

 ligament has been drawn slightly backwards. A section of the ligament 

 is transversely elongated, and it will be noticed that it is a structure 

 of considerable thickness. Immediately behind the ligament is the 

 tendon of the flexor perforans. This is not so broad as the ligament, 

 but it has a greater antero-posterior dimension. On either edge of this 

 tendon we find a nerve. These are the outer and inner plantar nerves. 

 In front of each nerve is a small vessel. These vessels are unnamed. 

 They are two small arteries which descend from the tarsal arch. In 

 front of each artery is a vein. The outer is the external metatarsal 

 vein, whilst the inner is the internal metatarsal, which is continued, 

 as we have already remarked, as the anterior root of the internal 

 saphena vein which crosses the seat of spavin. 



