44 



latter passes between the two heads of the gastrocnemius. Two or three 

 centimeters from its origin the A. femoris caudaHs divides into two branches 

 as may be seen upon turning aside the biceps femoris. (The external head 

 of the gastrocnemius may be partially transected close to its origin from 

 the femur.) One of the branches of the A. femoris caudalis passes upwards 

 or proximally, a short distance (4 to 6 cm.) between the semimemr 

 branosus and the biceps femoris and is distributed principally to the latter 

 muscle; it also gives off two branches, in this specimen, to the vastus 

 extemus. The other and larger branch of the A. femoris caudalis extends 

 downward and backward close to the posterior margin of the internal 

 head of the gastrocnemius and is distributed principally to the biceps 

 femoris and semitendinosus ; small branches are also supplied to the gastroc- 

 nemius and to the popliteal lymph gland. In the present specimen, about 

 I cm. peripheral to the A. femoris caudalis a small artery arises which passes 

 between the two heads of the gastrocnemius, immediately posterior to the 

 flexor perforatus, gives small branches to that muscle and to the perforans 

 and is continued as a slender vessel which accompanies the N. tibialis. 

 It unites with a small recurrent branch of the A. tibialis posterior a short 

 distance above the tarsus. In the present specimen, two additional arteries 

 originate from the A. poplitea about 4 cm. peripheral to the A. femoris cauda- 

 lis. The smaller of these two arteries goes to the external head of the gastroc- 

 nemius; the larger one is distributed to the distal portion of the biceps 

 femoris and the vastus extemus. The A. poplitea also gives off a small 

 branch to the internal head of the gastrocnemius. All the above arteries 

 are accompanied by veins. 



A. poplitea is the direct continuation of the A. femoralis. It runs between 

 the tibia and the Mm. popliteus and flexor perforans as far as to the proximal 

 part of the tibio-fibular or interosseous space where it divides into the A. 

 tibialis posterior and the A. tibialis anterior. Cut the M. popliteus a short 

 distance from its origin on the external epicondyle of the femur and draw 

 aside the muscle. Dissect between the M. peroneus and the flexor per- 

 forans. Insert the finger beneath the portion of the flexor perforans that 

 originates from the external tuberosity of the tibia and the adjoining portion 

 of the fibula and identify the tibio-fibvilar space (see skeleton). Taking 

 care not to injtire the underlying artery, cut the perforans close to the 

 external tuberosity of the tibia and the adjoining portion of the fibula; 

 draw back the muscle and demonstrate the A. poplitea as mentioned above. 

 It gives off a branch that enters the intercondyloid space of the femur and 

 supplies the femoro-tibial joint. 



A. tibialis posterior is the smaller of the two terminal branches of the A. 

 poplitea. Begin the dissection of this artery near its peripheral end, i.e. at 



