582 THE BLOOD- VASCULAR SYSTEM. 



glands, four or five in number, are found surrounding the artery ; one usually 

 lies superficial to the vessel ; another is situated between it and the bone, and the 

 rest are placed on either side of it. 



The Popliteal Artery, in its course downward from the aperture in the Adductor 

 magnus to the lower border of the Popliteus muscle, rests first on the inner surface 

 of the femur, and is then separated by a little fat from the hollowed popliteal 

 surface of the bone ; in the middle of its course it rests on the posterior ligament 

 of the knee-joint, and below on the fascia covering the Popliteus muscle. Super- 

 ficially, it is covered above by the Semimembranosus ; in the middle of its course, 

 by a quantity of fat, which separates it from the deep fascia and integument ; and 

 below it is overlapped by the Gastrocnemius, Plantaris, and Soleus muscles, the 

 popliteal vein, and the internal popliteal nerve. The popliteal vein, which is 

 intimately attached to the artery, lies superficial and external to it above ; it then 

 crosses it and lies to its inner side. The internal popliteal nerve is still more 

 superficial and external above, but below the joint it crosses the artery and lies 

 on its inner side. Laterally, the artery is bounded by the muscles which are 

 situated on either side of the popliteal space. 



PLAN OF RELATIONS OF POPLITEAL ARTERY. 



In front. 

 Femur. 



Ligamentum posticum. 

 Popliteus. 



Inner side. Outer 



Semimembranosus. / Popliteal \ Biceps. 



Internal condyle. 1 Artery. I Outer condyle. 



Gastrocnemius (inner head). Gastrocnemius (outer head). 



\ x ^_ Plantaris. 



Behind. 



Semimembranosus. 



Fascia. 



Popliteal vein. 



Internal popliteal nerve. 



Gastrocnemius. 



Plantaris. 



Soleus. 



Peculiarities in Point of Division. Occasionally the popliteal artery divides prematurely 

 into its terminal branches ; this unusual division occurs most frequently opposite the knee-joint. 

 The anterior tibial under these circumstances may pass in front of the Popliteus muscle. 



Unusual Branches. The artery sometimes divides into the anterior tibial and peroneal, 

 the posterior tibial being wanting or very small. Occasionally the popliteal is found to divide 

 into three branches, the anterior and posterior tibial and peroneal. 



Surface Marking. The course of the upper part of the popliteal artery is indicated by 

 a line drawn from the outer border of the Semimembranosus muscle at the junction of the 

 middle and lower third of the thigh obliquely downward to the middle of the popliteal space, 

 exactly behind the knee-joint. From this point it passes vertically downward to the level of a 

 line drawn through the lower part of the tubercle of the tibia. 



Surgical Anatomy. The popliteal artery is not infrequently the seat of injury. It may be 

 torn by direct violence, as by the passage of a cart-wheel over the knee or by hyper-extension of 

 the knee ; and in the dead body, at all events, the middle and internal coats may be ruptured by 

 extreme flexion. It may also be lacerated by fracture of the lower part of the shaft of the 

 femur or by antero-posterior dislocation of the knee-joint. It has been torn in breaking down 

 adhesions in cases of fibrous ankylosis of the knee, and is in danger of being wounded, and in 

 fact has been wounded, in performing Macewen's operation of osteotomy of the lower end of the 

 femur for genu valgum. In addition, Spencer records a case in which the popliteal artery was 

 wounded from in front by a stab just below the knee, the knife passing through the interosseous 

 space. The popliteal artery is more frequently the seat of aneurism than is any other artery 

 in the body, with the exception of the thoracic aorta. This is due no doubt, in a great 

 measure to the amount of movement to which it is subjected, and to the fact that it is supported 

 by loose and lax tissue only, and not by muscles, as is the case with most arteries. 



Ligature of the popliteal artery is required in cases of wound of that vessel, but for aneurism 

 of the posterior tibial it is preferable to tie the superficial femoral. The popliteal may be tied 

 in the upper or lower part of its course ; but in the middle of the ham the operation is attended 





