90 THE SURGICAL ANATOMY OF THE HORSE 



the middle third of the metacarpus, when it is reflected on to the 



tendons. 



Accompanying the tendons through the tube are the large metacarpal 

 artery and the plantar nerves, the artery running with the internal 

 plantar nerve in close proximity to the inner edge of the tendon of the 

 perforans. But the small metacarpal artery runs outside the tube on the 

 inner aspect of the joint, where it is accompanied by the internal metacarpal 

 vein. These two vessels are therefore very liable to injury in "speedy 

 cuttino-," since they have not the protection of the fibrous band which 

 covers the large metacarpal artery, &c. 



Cutaneous branches from the ulnar nerve run over the anterior and 

 outer aspects of the joint. 



It has already been stated that the subcarpal or check ligament is 

 the downward continuation of the posterior common ligament of the 

 knee. This ligament, which is of such considerable surgical import, 

 takes a course which is obliquely downwards and slightly backwards, and 

 at a distance which varies from three to four inches below the lowest 

 transverse carpal joint it becomes united to the tendon of the perforans 

 muscle. The relations of this ligament are as follows : In front it is 

 opposed to the posterior surface of the suspensory or superior sesamoidean 

 ligament ; behind it we have the tendon of the perforans (Plate XXVI.), 

 to which it is attached inferiorly. Superiorly it is attached to the 

 posterior common ligament. Its lateral edges are related in the upper half 

 of their extent to the inner surfaces of the small metacarpal bones, and in 

 their lower half to the skin and subcutaneous fascia. It is therefore only 

 in its lower portion that the ligament can be felt in the living animal. 



At the postero-inferior aspect of the knee we have the suspensory 

 ligament, which takes origin from the back ot the lower row of carpal 

 bones and the upper extremity of the large metacarpal. This ligament, 

 it should be noted, is next the bones, and in this region is interposed 

 between them and the subcarpal ligament. A complete description of 

 the ligament will be given later. 



Between the tendon of the extensor metacarpi magnus and the anterior 



