480 The Knee-joint 



from the inner and back part. In this operation there is risk of 

 wounding the anastomotica magna, the superior or internal articular, 

 or even the popliteal artery itself. The articular artery, however, 

 ought to be well below the track of the osteotome, and the anastomo- 

 tica, running down close in front of tendon of the adductor magnus, 

 should be behind it. 



The popliteus arises inside the capsule of the joint by a round 

 tendon from the front of a groove on the outer condyle of the femur. 



The tendon passes between the external semilunar cartilage, which 

 it grooves, and the external lateral ligament. As it escapes beneath 

 the outer part of the posterior ligament it is enclosed in a prolongation 

 from the synovial membrane of the joint. It then spreads into a tri- 

 angular fleshy layer, which is inserted above the oblique line of the tibia. 



The insertion is covered by an expansion from the attachment of 

 the semi-membranosus, and has resting on it the popliteal vessels, the 

 internal popliteal nerve, and the heads of the gastrocnemius. Its nerve 

 (from the internal popliteal) turns round its lower border to supply it 

 on the anterior surface. 



Excision of the knee-joint is performed by making a deep, cres- 

 centic cut convex downwards from one tuberosity of the femur, 

 through the ligamentum patellae to the other tuberosity, and turning 

 up the flap of the quadriceps with the sesamoid bone in it ; for, unless 

 this bone is extensively diseased, it had better be left. The lateral and 

 crucial ligaments being divided, and the end of the femur cleared, the 

 knee is well bent, and the condyles are sawn off by directing the saw 

 vertically -to the head of tibia ; thus the risk of wounding the popliteal 

 artery is inconsiderable. As little as possible should be removed, so 

 that the line of the junction-cartilage may not be approached, or at 

 least implicated. 



The head of the tibia is then thrust out of the wound and sliced off, 

 and the sawn surface adjusted and fixed ; but its sharp edge must not 

 be allowed to fall back on to the popliteal artery, or secondary 

 haemorrhage may occur, amputation being then needed. Provision 

 may be made for the free escaps of discharges through the cornua of 

 the incision, or by bringing a tube through the posterior ligament 

 the joint and out through the skin, passing it between the poplite 

 vessels and the external popliteal nerve. 



THE POPLITEAL SPACE 



The popliteal space is bounded above by the diverging 

 strings and below by the converging heads of the gastrocnemius. 

 It is covered in by skin and superficial fascia, and by the fascia lata. 

 The floor is formed by the lower fourth of the femur, the posterior 

 ligament of the knee-joint, and the upper sixth of the tibia, with the 

 popliteus. 



