314 



OPEEATIONS ON MUSCLES AND THEIR ANNEXES. 



anchylosis of the fetlock ; exostoses ; adhesions between the ten- 

 dons and the bones ; large engorgements of the tendinous struc- 

 ture ; or chronic dilatation of the synovial bursse sm-rounding the 

 region of the fetlock. Remediable cases would seem, from this, to 

 constitute rather a small minority of the whole number. 



The fibrous tissues acted upon in plantar tenotomy, are the 

 tendons of the flexors of the phalanges, in that part of their length 

 which is situated back of the cannon bone, between the carpal or 

 tarsal sheath and the fetlock. The superficial tendon reaching the 

 fetlock forms a ring through which the deep flexor passes, a cir- 

 cumstance from which has been devised the manner of perforatus 

 and perforans, by which they are known. 



Fig. 328.— Median section at tbe infe- 

 rior row of the carpus— of the metacar- 

 pus and suspensory ligament. 



1. Os magnum. 



2. Posterior common ligament of the 

 carpus. 



3. Band to the perforans. 



4. Suspensory ligament. 



5. Its superficial layer. 



6. The deep. 



7. Principal metacarpal bone. 



The superficial tendon is covered by the fibrous expansion of 

 the two carpal and metacarpo-phalangeal sheaths in the fore, and 

 by the tarsal and metatarso-phalangeal in the hind leg. The deep 

 flexor toward the middle of the cannon receives a strong, fibrous 

 band coming from the posterior ligament of the carpus or tarsus. 

 Below and between the two small metacarpal or metatarsal bones 

 is the suspensory ligament, a strong band, thin suj)eriorly at its 

 origin, and bifid inferiorly. Between the suspensory ligament and 

 the cannon bone, there is an interosseous vein and the two inter- 

 osseous arteries ; on the side of the tendons, the internal and ex- 

 ternal collateral veins, with, in the fore leg, the principal artery 



