THE REGION OF THE KNEE 445 



where it terminates by dividing into the anterior and posterior 

 tibial arteries. Throughout its course the artery is very deeply 

 placed, and it lies in direct contact with the posterior ligament 

 of the knee-joint. , 



Ligature of the Popliteal Artery may be carried out for 

 aneurism, or following wounds of the vessel. The incision lies 

 behind and parallel to the tendon of the adductor magnus, 

 and when the skin is divided, the great saphenous vein and the 

 saphenous nerve are exposed. These structures are retracted 

 backwards together with the sartorius, which is seen when the 

 deep fascia is incised (Fig. 128). The wound is then deepened 

 between the adductor magnus and the semimembranosus. 

 Flexion of the knee relaxes the latter muscle and enables it to 

 be retracted so as to permit the finger to be inserted into the 

 fat which intervenes between the popliteal artery and the femur. 

 The sheath of the vessel is carefully incised on its medial aspect,, 

 and the popliteal vein and the tibial nerve, which lie on its 

 postero-lateral side, are thus avoided. 



The Branches of the Popliteal Artery can be divided into three groups : 

 (a) muscular, (b) cutaneous, (c) articular, (a) The proximal muscular branches 

 supply the hamstrings and anastomose with the perforating arteries (p. 410); 

 the distal muscular branches are distributed to the muscles of the calf, (b) 

 The cutaneous branch supplies the skin of the calf, and is accompanied by the 

 medial cutaneous branch of the tibial nerve, (c) The articular branches are 

 five in number : 



1. The middle genicular (azygos) artery enters the knee-joint by piercing 

 the posterior ligament, and is distributed to the structures within the capsule. 



2. The superior genicular arteries, lateral and medial, wind round the 

 femur, proximal to the condyles. They are in close contact with the bone, 

 and anastomose with one another anteriorly. In addition, they anastomose 

 with the inferior genicular arteries, and with the descending branch of the 

 lateral circumflex and the articular branch of the arteria genu suprema 

 (p- 4 I 3)- The latter anastomosis helps to re-establish the circulation in the 

 leg when the popliteal artery is ligatured in its proximal part. 



3. The inferior genicular arteries, lateral and medial, wind round to the 

 anterior aspect of the knee. In their course they pass under cover of the 

 tibial and fibular collateral (internal and external lateral) ligaments respec- 

 tively, and they anastomose with one another under cover of the ligamentum 

 patellae. They communicate with the superior genicular arteries, and so 

 take part in the important anastomosis around the knee-joint. 



The Tibial (Internal Popliteal) Nerve (L. 4, 5, S. i, 



2, 3) arises from the sciatic in the posterior compartment of 

 the thigh and extends distally in the middle line of the limb. 

 In the popliteal fossa it lies superficial to the popliteal vessels 

 and it crosses them obliquely from the lateral to the medial side. 

 At the distal border of the popliteus the tibial nerve passes 



