126 THE SURGICAL ANATOMY OF THE HORSE 



from the knee is the carpal sheath. These sheaths do not communicate 

 with one another ; neither do they touch one another, since there is an 

 interval between them. This interval is about one inch in extent, and it 

 will be easily understood that if we desire to cut down on to the tendons 

 without opening into one or other of these sheaths, which would be 

 a most undesirable complication, we must make our incision over the 

 interval between them, i.e., above the button of the small metacarpal 

 bone. 



TENOTOMY OF THE PERFORANS 



In operating on the perforans tendon alone, an incision is made in 

 the middle third of the cannon region, between the two tendons. This 

 incision, therefore, will be about three-quarters of an inch behind a 

 vertical line drawn through the incision made in performing plantar 

 neurectomy. The lips of the incision are to be separated and the 

 anterior lip drawn well forward. This should enable the operator to 

 see the nerve and the artery, and he may then push both slightly 

 forward under the vein with a probe, and hold them in that position by 

 means of the thumb of the left hand applied to the skin, the fingers of 

 the same hand being passed round the front of the limb to draw the 

 vessels, &c., of the other side forwards. 



An incision should now be made in the connective tissue uniting the 

 two tendons, which should be of sufficient extent only to accommodate 

 the tenotome. The tenotome, which must have a blunt extremity, in 

 order that the skin of the opposite side of the limb may not be incised, 

 is now passed flatwise in between the tendons, the blade is turned with 

 its cutting edge directed towards the perforans tendon, and by the 

 rocking movement previously described the tendon is divided. 



During the operation the assistants continue to extend the knee 

 forcibly, so that a sudden jerk occurs when the tendon is severed and 

 the divided ends recede some distance from one another. 



