POPLITEAL NERVES AND BRANCHES. 129 



anastomosing with the other vessels on the articulation, and with 

 the recurrent branch of the anterior tibial artery ; it sends an offset 

 beneath the ligament of the patella to join a twig from one of the 

 internal branches. 



The internal art cry ramifies over the front of the internal internal, 

 tuberosity of the tibia, and anastomoses with the upper internal 

 and lower external articular branches, and with the superficial 

 branch of the anastomotic artery. 



5. The a-zygos branch enters the joint through the posterior liga- Ami one 

 ment, and is distributed to the ligamentous structures, the fat, and artery. 1 

 the synovial membrane of the interior. 



The POPLITEAL VEIN (fig. 53, h) originates in the union of the Popliteal 

 anterior and posterior tibial venae coinites, and has the same extent ^ e 

 and relations as the artery it accompanies. At the lower border of position to 

 the popliteus muscle the vein is internal to the arterial trunk ; the arter y 

 between the heads of the gastrocnemius, it is superficial to that 

 1 ; and thence to the opening in the adductor magnus it lies to 

 the outer side of, and close to, the artery. It is joined by branches branches, 

 corresponding with those of the artery, as well as by the short 

 s-aphenous vein. 



The POPLITEAL NERVES (fig. 51> p. 126) are the two large Popliteal 

 trunks derived from the division of the great sciatic in the thigh "wo*, 68 

 (p. 133), and are named internal and external. Each furnishes inner and 

 cutaneous and articular offsets, but only the inner one supplies outer - 

 branches to muscles. 



The INTERNAL POPLITEAL NERVE ( 2 ) is larger than the external. Internal 

 and occupies the middle of the ham : its relations are similar to 

 those of the artery, that is to say, it is partly superficial, and 

 partly covered by the gastrocnemius. The nerve is continued to 

 the back of the leg, where it is called posterior tibial ; the name 

 popliteal is retained only to the lower border of the popliteus 

 muscle. Its position to the vessels has been already noticed, branches 

 The branches arising from it are the following: 



a. Two small articular tu:igs (fig. 53, 9 ) are furnished to the knee- two 



. . , .,, , A*. i . i articular; 



joint with the vessels. One accompanies the lower internal 

 articular artery to the front of the articulation, and is the larger ; 

 the other takes the same course as the azygos artery, and enters the 

 back of the joint with it. 



b. Muscular branches arise from the nerves between the heads of four 



the gastrocnemius. One is furnished to each head of the gastro- muscular > 

 cnemin.s, and the outer of these usually supplies the plantaris. 

 Another descends beneath the gastrocnemius, and enters the pos- 

 terior surface of the soleus. And a fourth penetrates the popliteus 

 at the anterior aspect, after turning round the lower border. 



c. The tibial communicating branch (fig. 71, 3 , p. 188) is a an done 

 cutaneous offset to the leg and foot. It lies beneath the fascia, and the tibia?' 

 between the heads of the gastrocnemius, as far as the middle of the 



leg, where it becomes superficial, and unites with the peroneal com- 

 municating branch of the external popliteal, to form the short 

 saphenous nerve (p. 187). 



