198 THE SURGICAL ANATOMY OF THE HORSE 



course taken by this branch is horizontally backwards and it passes into 

 the semitendinosus muscle. It gives off a long collateral branch which 

 ascends to supply the biceps femoris muscle, and which anastomoses with 

 the profunda or deep femoral artery ; and descending branches which 

 supply the gastrocnemius. 



The femoral artery is in intimate relationship to the inferior third 

 of the bone where it crosses the back of the shaft in the femoral 

 groove. In fractures of this portion of the femoral shaft, therefore, 

 the artery is usually involved, as already remarked in our chapter 

 on Bones and Fractures. 



THE POPLITEAL ARTERY 



This vessel is the direct continuation of the femoral artery. It 

 passes between the two heads of the gastrocnemius muscle and 

 becomes insinuated beneath the popliteus. It then runs almost 

 vertically over the femoro-tibial joint between the deep face of the latter 

 muscle and the posterior surface of the posterior common ligament. 

 The vessel is about six inches in length, and on arriving near the 

 tibio-fibular arch it divides into the anterior and posterior tibial 

 arteries. 



As it passes over the back of the posterior common ligament, it gives 

 off several small branches which penetrate the ligament and are dis- 

 tributed to the internal structures of the stifle joint. Several muscular 

 branches are also given off, which are distributed particularly to the 

 gastrocnemius and soleus muscles. One of these branches follows the 

 course taken by the flexor perforatus muscle, and in front ot the tendo- 

 Achilles it anastomoses with a retrograde branch from the posterior tibial 

 artery. 



The femoro-popliteal artery is sometimes regarded as a branch of the 

 popliteal artery. 



