818 THE VASCULAR SYSTEM. 
(a) The superficial branch (ramus saphenus) passes through the lower end of Hunter’s 
canal with the long saphenous nerve, and appears superficially on the inner side of the 
knee between the gracilis and the sartorius. It gives twigs to the integument of the 
upper and inner part of the leg, and it anastomoses with the inferior internal articular 
artery. (+) The deep branch (ramus musculo-articularis) descends in the ‘substance of 
the vastus internus along the anterior aspect of the tendon of the adductor magnus. 
It anastomoses with the superior internal articular artery, and it sends branches outwardel 
one on the surface of the femur and another along the upper border of the patella, to 
anastomose with the descending branch of the external circumflex, the inferior perforating 
artery, the superior external articular, and the anterior tibial recurrent. 
THE POPLITEAL ARTERY. 
The popliteal artery (a. poplitea) is the direct continuation of the femoral. It 
commences at the upper and inner part of the popliteal space, under cover of the 
semimembraneous, and terminates at the lower border of the popliteus muscle, and 
on a level with the lower part of the tubercle of the tibia, by dividing into the 
anterior and the posterior tibial arteries. 
From its origin the artery descends, with an outward inclination, to the inter- 
space between the condyles of the femur, whence it 1s continued vertically down- 
wards to its termination. 
Relations.— A nterior.—It is in contact in front and from above downwards with the 
popliteal surface of the femur, the posterior ligament of the knee-joint, and the fascia 
covering the posterior surface of the popliteus. : 
Posterior.—The artery is overlapped behind by the outer border of the semi- 
membranosus above ; it is crossed about its middle by the popliteal vein and the internal 
popliteal nerve, the ‘vein intervening between the artery and the nerve ; whilst in the 
lower part of its extent it is overlapped by the adjacent borders of the two heads of the 
gastrocnemius, and crossed by the nerve to the popliteus and by the plantaris muscle. . 
Lateral.—On its outer side it is in relation above with the internal popliteal nerve and ~ 
the popliteal vein, then with the outer condyle of the femur, and below with the outer 
head of the gastrocnemius and with the plantaris. 
On the inner side it is in relation above with the semimembranosus, in the middle 
with the inner condyle of the femur, and below with the internal popliteal nerve, the 
popliteal vein, and the internal head of the gastrocnemius. Popliteal lymphatic glands 
are arranged irregularly around the artery. 
Branches.—(1) Muscular branches are given off in two sets, upper and lower. 
The upper muscular branches are distributed to the lower parts of the hamstring 
muscles, in which they anastomose with branches of the profunda artery. 
The lower muscular, or sural, arteries (aa. surales) enter the upper parts of the gastro- 
cnemius, the plantaris, the soleus, and the popliteus muscles, and they EE EOITAOS with 
branches of the posterior tibial artery and the lower articular arteries. 
(2) The articular branches are five in number—viz. upper and lower external, upper 
and lower internal, and an azygos branch. 
(a) The superior external articular artery (a. genu superior lateralis) passes outwards 
above the external condyle, behind the femur and in front of the biceps tendon, into the 
vastus externus, where it anastomoses with the anastomotic, the descending branch of the — 
external circumflex, and the lowest perforating artery ; it also sends branches downwards 
to anastomose with the inferior external articular and with the anterior tibial recurrent. 
(4) The superior internal articular artery (a. genu superior medialis) passes inwards 
above the internal condyle, behind the femur, and in front of the tendon of the adductor 
magnus, into the vastus internus. It anastomoses with branches of the anastomotic and 
of the superior external articular artery. 
(c) The inferior external articular artery (a. genu inferior lateralis) runs outwards across 
the popliteus muscle and in front of the plantaris and the external head of the gastro- 
cnemius ; then turning forwards, it is joined by the inferior external articular nerve, and 
passes to the inner side of the external lateral ligament, where it terminates by anasto- 
mosing with its fellow of the opposite side and with the superior external articular and 
anterior tibial recurrent arteries. 
(/) The inferior internal articular artery (a. genu inferior medialis) passes inwards below 
the inner tuberosity of the tibia, along the upper border of the popliteus and in front of 
