Popliteal Aneurysm 483 



articular branches, and with the anterior tibial recurrent. Each 

 inferior aiticular artery lies beneath a head of the gastrocnemius. 

 Toe central articular, or azygos, pierces the ligamentum posticum. 



As their names imply, all these rive arteries are for the nutrition of 

 the articulation. 



The popliteal vein begins at the lower border of the popliteus, 

 by the confluence of the venae comites of the anterior and posterior 

 tibial arteries, and possibly also of those of the peroneal artery. At 

 its commencement it is to the inner side of the artery, but as it as- 

 cends between the heads of the gastrocnemius, and between the con- 

 clyles of the femur, it lies superficial to, that is behind, the artery, and 

 in the upper part of the space it is to its outer side. Its tributaries are 

 the five articular, the external saphenous vein, and muscular branches 

 sural and crural. 



The popliteal lymphatic glands, four or five in number, are 

 lodged in the loose connective tissue in the depths of the space, one 

 of them being generally placed upon the artery, which thus, when in- 

 flamed and enlarged, constitutes a pulsating tumour in the ham and 

 may be mistaken for an aneurysm. 



The popliteal glands receive their lymph from the back of the leg, 

 he outer side of the foot, and from the lower part of the back of the 

 thigh. (Superficial lymphatic vessels usually run with the neighbouring 

 superficial veins.) 



For the course and branches of the internal and external popli- 

 teal nerves see pp. 380 and 381, and for the obturator nerve in the 

 space see p. 359. 



Aneurysm of the popliteal artery is of common occurrence, for, 

 as the artery is just behind the joint, it is constantly being bent and 

 straightened ; and, with arterial disease, a sudden and violent move- 

 ment of the knee is apt to crack the inner coats. The outer coat is 

 then dilated, and a pulsating tumour occurs in the ham ; this is best 

 examined when the patient is prone and the knee flexed, as the fascia 

 lata is then slackened and the depths of the space are rendered acces- 

 sible to the fingers. An enlarged lymphatic gland over the artery 

 would also give rise to a pulsating tumour, which, like aneurysm, would 

 be less prominent and would cease to pulsate, when the common 

 femoral was compressed, but it would not give that lateral impulse 

 which characterises aneurysm. 



The aneurysm may compress the vein, and so cause congestion, 

 varix, and oedema of foot and leg, or even gangrene. Pressing upon 

 the internal popliteal nerve, it may set up peripheral pains and numb- 

 ness, and local insensibility. Causing stiffness of the knee, it is r.pt 

 to be taken at first for ' rheumatism.' Finally it may burst into the 

 joint, distending it with blood ; or its contents may be extravasated 

 from the popliteal space into the back of the thigh and leg. When 

 the artery bursts, pulsation ceases at the knee and in the posterior 



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