586 THE ARTERIES 



femoral just before the latter perforates the adductor magnus muscle, and almost 

 immediately divides into two branches, (a) a superficial and {h) a deep. These 

 branches may sometimes come off separately from the femoral. 



(a) The superficial branch pierces the aponeurotic covering of Hunter's canal, 

 passes between tlic sarturius and gracilis muscles along with the internal sa})henous 

 nerve, and, perforating the deep fascia, supplies the skin of the upper and inner 

 side of the leg and anastomoses with the inferior internal articular branch of the 

 popliteal and the other vessels forming the plexus or rete at the inner side of the 

 knee. In its course it gives twigs to the lower part of the sartorius and gracilis 

 muscles. 



{h) The deep branch runs downwards in front of the adductor magnus tendon, 

 burrowing amongst the fibres of the vastus internus as far as the internal condyle, 

 where it passes into the plexus or rete on the inner side of the knee-joint, 

 anastomosing with the internal inferior articular branch of the popliteal, the 

 anterior tibial recurrent, and the external superior articular branch of the ])opliteal 

 across the front of the femur just above the articular surface of the knee-joint. In 

 common with the rest of the rete it sends branches into the knee-joint. It also 

 supplies branches to the vastus internus and crureus muscles. 



THE POPLITEAL ARTERY 



The popliteal artery (fig. 375) runs through the popliteal space or ham. It is 

 a continuation of the femoral, and extends from the aponeurotic opening in the 

 adductor magnus at the junction of the middle with the lower third of the thigh to 

 the lower border of the popliteus muscle, Avhere it terminates by dividing into the 

 posterior and anterior tibial arteries. This division is on a level with the lower 

 border of the tubercle of the tibia. As the artery passes through the opening in 

 the adductor magnus, it is accompanied by the popliteal vein, and at times by the 

 branch of the obturator nerve to the knee-joint. The vein throughout is behind 

 the artery, at first lying a little external to it, but as the vessels pass through the 

 popliteal space the vein crosses obliquely over the artery, and at the termination 

 of the artery lies a little to its inner side. The internal popliteal nerve is 

 superficial to both artery and vein. As it enters the space it is well to the outer 

 side of the vessels, but as it descends it gradually approaches them, crosses behind 

 them, and at the lower part of the space lies to their inner side. The artery 

 in the whole of its course is deeply placed and covered by a considerable amount 

 of fat and cellular tissue. 



Relations (fig. 374). — In front, the artery lies successively on the popliteal 

 surface of the femur (from which it is separated l^y a little fat and sometimes one 

 or two small glands) ; on the posterior ligament of the knee; on the hinder edge of 

 the articular surface of the head of the tibia; and on the popliteus muscle. From 

 the latter muscle it is separated by the expansion from the semi-membranosus which 

 covers the muscle, and is attached to the oblique line on the tibia. 



Behind, the artery is covered, above by the semi-membranosus; in the centre of 

 the space by the skin, superficial and deep fascia; and below by the inner head of 

 the gastrocnemius. The popliteal vein is behind it in the whole of its course. The 

 internal popliteal nerve crosses behind it ol)li(|uely from without inwards, about the 

 centre of the space. As the artery divides into the anterior and posterior tibial, 

 it is crossed by the aponeurotic arch of the soleus which stretches between the 

 tibial and fi))ular origins of that muscle. 



To the inner side are the semi-membranosus above, and the inner head of the 

 gastrocnemius and the internal popliteal nerve below. 



To the outer side are the biceps and the internal popliteal nerve above, and 

 the outer head of the gastrocnemius and the plantaris below. 



Principal variations in the popliteal. — (A) It luaj' divide higher, or more rarely lower than 

 usual. (B) It may divide into the anterior tibial and peroneal. (C) The vein may he deeper 

 than the artery, or separated irom it by a .slip of the gastrocnemius. 



