638 THE ARTERIES. 



lying close to the tendon of the Biceps muscle. More deeply at the bottom of the 

 space are the popliteal vessels, the vein lying superficial and a little external to the 

 artery, to which it is closely united by dense areolar tissue ; sometimes the vein 

 is placed on the inner instead of the outer side of the artery ; or the vein may be 

 double, the artery lying between the two vengecomites, which are usually connected 

 by short transverse branches. More deeply, and, at its upper part, close to the 

 surface of the bone, is the popliteal artery, and passing off from it at right angles 

 are its articular branches. The articular branch from the obturator nerve descends 

 upon the popliteal artery to supply the knee, and occasionally there is found deep 

 in the space an articular filament from the great sciatic nerve. The popliteal 

 lymphatic 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 until near the 

 termination of the artery, when the vein 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 rcuscles which are situated on either side of the popliteal space. 



PLAN or RELATIONS OF POPLITEAL ARTERY. 



In front. 

 Femur. 



Ligamentum posticum. 

 Popliteus. 



Inner side. f Outer side. 



Semimembranosus. I p op iiteal ] Biceps. 



Internal condyle. 1 Artery. I Outer condyle. 



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



Internal popliteal nerve (below). Plantaris. 



Internal popliteal nerve (above). 

 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. 



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 



