34 THE SURGICAL ANATOMY OF THE HORSE 



the tendon of the gastrocnemius muscle which is seen running to 

 its insertion into the summit of the tuber calcis. Behind the 

 gastrocnemius tendon is that of the flexor perforatus. Superiorly the 

 two tendons are intimately related to one another, but at the summit 

 of the tuber calcis they are seen to be separated by a small synovial 

 bursa. This bursa lies on the summit of the tuber and extends 

 upwardly for a short distance between the tendons. Its function is to 

 facilitate the play of the tendon of the flexor perforatus over the summit 

 of the tuber calcis. It is of importance, as it is sometimes implicated 

 in the surgical condition known as capped hock. 



It is plainly seen that the perforatus tendon runs over the summit of 

 the tuber calcis and does not, therefore accompany the tendon of the 

 flexor perforans through the tarsal sheath — an important difference 

 between the relationship of these two tendons and the corresponding 

 tendons in the fore limb. 



The section of the tuber calcis is elongated from above to below and 

 approaches the elliptical in outline. Below the tuber, it will be observed 

 that the tendon of the flexor perforatus becomes placed immediately 

 behind that of the flexor perforans after the latter has left the tarsal 

 sheath, and the two tendons bear this relationship to each other for 

 the remainder of their course down the metatarsal region. 



Articulated to the inferior extremity of the tibia is the astra- 

 galus. In outline a section of this bone presents a peculiar appear- 

 ance, somewhat approaching the circular with a well-marked outcut 

 posteriorly for articulation with the body of the calcis. This latter bone is 

 broader above than below. Anteriorly it is articulated to the astragalus, 

 as stated. Posteriorly it is related to the tarsal sheath with the 

 perforans tendon. Inferiorly it is articulated in front to the scaphoid, 

 whilst behind it gives attachment to the tarso-metatarsal ligament. 

 This ligament, it may be noticed, closes in posteriorly the joints formed 

 by the small tarsal bones, and is directly continued inferiorly as the 

 subtarsal or check ligament which proceeds in the downward direction 



