94 LAMENESS OF THE HORSE 



oleenmon. The two heads unite at the upper third of the radius 

 and the muscle, becoming tendinous, as is the case with the other 

 carpal flexors, is attached by one point of insertion to the acces- 

 sory carpal bone (trapezum). The other blends with the 

 posterior annular ligament of the carpus. 



The ulnaris lateralis (flexor metacarpi externus) has its origin 

 from the lateral epicondyle of the humerus and inserts to the 

 proximal extremity of the fourth metacarpal (outer splint) 

 bone and by another attachment to the accessory carpal bone 

 (trapezium) with the tendon of the flexor carpiulnaris (flexor 

 metacarpi medius). 



Acting together, these muscles flex the carpus or extend the 

 elbow and this action is antagonized by the biceps brachii (flexor 

 brachii) and extensors of the carpus and phalanges. 



Etiology and Occurrence. — Inflammation of the muscular or 

 tendinous parts of tlie carpal flexors, does not occur as fre- 

 quently as does inflammation of the flexors of the extremity. 

 They are subject to injury such as is occasioned by hard work 

 and concussion and contract as a result ; but, more frecjuently 

 a congenital malformation of the leg is responsible for undue 

 strain upon these parts. Horses that are "knee sprung" or that 

 have a congenital condition where in the anterior line, as formed 

 by the radius, carpal and metacarpal bones, is bent forward at 

 the carpus, are subject to inflammation and contraction of the 

 carpal flexors. When these flexors are contracted, the condition 

 is commonly known among horsemen as "buck knee." In itself, 

 intlaiiimation of the carpal flexors is not a condition which is 

 likely to prove troulilesome, l)ut because of carpal involvement 

 (which is often present) the cause of the troul)le remains, and 

 inHaiinnation of the carpal flexors recurs or becomes chronic 

 and contraction of tendons results. 



Symptomatolog-y. — Inflammation of the carpal flexors, when 

 acute and uiici»iii|)licated, is characterized ]\v a painfully swollen 

 condition of the afl'cctcd tendons. No weight is ])orne upon 

 the affected leg and tlic carpal joint is flexed. .Mixed huneness 

 is present. There is no difficidty encountered in arriving at a 

 diagnosis because of Ihe very noticeably inHamed parts. 



