Popliteal Space 481 



In the superficial fascia ascends the external saphenous vein, 



which, beginning in an arch on the dorsum of the foot, in communica- 

 tion with the internal or long saphenous vein, passes behind the 

 external milleolus, and be;ween the bellies of the gas'.rocneinius, to 

 pierce the fascia lata at the middle of the space. Like the long vein, it 

 receives tributaries just before traversing the deep fascia ; these are 

 cutaneous branches descending from the back of the thigh. Sometimes 

 when a tumour presses upon the popliteal or superficial femoral vein 

 these descending branches are engorged and dilated. There is a 

 communication between the vena? comites of the posterior tibial artery 

 and the external saphenous vein near the ankle, and a branch on the 

 thigh again links the two saphenous veins. The short saphenous nerve 

 accompanies the external saphenous vein between the bellies of the 

 gastrocnemius. 



The cutaneous nerves of the space are branches of the small 

 sciatic. 



In the undissected limb the space is small, as the muscles which 

 bound it closely overlap the artery. Thus, superficially, on the outer 

 side, are the biceps, the outer head of the gastrocnemius, and the 

 plantaris ; and on the inner side are the semi-membranosus and the 

 other head of the gastrocnemius. 



The deep fascia is a continuation of the fascia lata, and it receives 

 slips from the hamstring tendons. Its density prevents digital explora- 

 tion of the depths of the space unless it be first slackened by bending 

 the knee. 



Close on the inner side of the tendon of the biceps runs the external 

 popliteal nerve ; the internal popliteal nerve descends in the middle 

 line. 



The popliteal artery enters the top of the space with the popliteal 

 vein. The fact of these vessels coming through the opening in ih) 

 adductor magnus, at the lower end of Hunter's canal, on the inner 

 side of the shaft of the femur, suffices to place them well on the inner 

 side at the top of the space. And, inasmuch as they are coming from 

 the front of the thigh, they are very deeply placed on their entrance 

 into the ham. Now, as the internal popliteal nerve is coming boldly 

 down the back of the thigh into the middle of the space, it necessarily 

 lies at first considerably external and superficial to the popliteal vessels. 



The relative position of the vein and artery at the top of the 

 space is the same as (p. 454) in Hunter's canal which actually ends 

 at the top of the space ; the vein is on the outer side of the artery, 

 and they are both resting upon the femur. 



The passage from the crural to the sural (sura, calf) part of the 

 ham is the notch between the condyles of the femur, and it is far too 

 narrow to allow the nerve, the vein, and the artery to go through 

 abreast ; they are arranged, therefore, in single file, the vessels sti'l 

 being deeper than the nerve. In their preparation for the passage 



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