'NDESMOLOGY 



of the femoral, the genicular branches of the popliteal, the recurrent branches of the anterior 

 tibial, and the descending branch from the lateral femoral circumflex of the profunda femoris. 



The nerves are derived from the obturator, femoral, tibial, and common peroneal. 



Movements. The movements which take place at the knee-joint are flexion and extension, 

 and, in certain positions of the joint, internal and external rotation. The movements of flexion 

 and extension at this joint differ from those in a typical hinge-joint, such as the elbow, in that 

 (a) the axis around which motion takes place is not a fixed one, but shifts forward during extension 

 and backward during flexion; (6) the commencement of flexion and the end of extension are 

 accompanied by rotatory movements associated with the fixation of the limb in a position of 

 great stability. The movement from full flexion to full extension may therefore be described 

 in three phases: 



1. In the fully flexed condition the posterior parts of the femoral condyles rest on the corre- 

 sponding portions of the meniscotibial surfaces, and in this position a slight amount of simple 

 rolling movement is allowed. 



Posterior cruciate 

 ligament 



Medial meniscus 



Tibial collateral 





Anterior cruciate 

 ligament 



Lateral meniscus 



Fibular collateral 

 ligament 



Fia. 352. Capsule of right knee-joint (distended). Posterior aspect. 



2. During the passage of the limb from the flexed to the extended position a gliding movement 

 is superposed on the rolling, so that the axis, which at the commencement is represented by a 

 line through the inner and outer condyles of the femur, gradually shifts forward. In this part 

 of the movement, the posterior two-thirds of the tibial articular surfaces of the two femoral 

 condyles are involved, and as these have similar curvatures and are parallel to one another, they 

 move forward equally. 



3. The lateral condyle of the femur is brought almost to rest by the tightening of the anterior 

 cruciate ligament; it moves, however, slightly forward and medialward, pushing before it the 

 anterior part of the lateral meniscus. The tibial surface on the medial condyle is prolonged 

 farther forward than that on the lateral, and this prolongation is directed lateralward. When, 

 therefore, the movement forward of the condyles is checked by the anterior cruciate ligament, 

 continued muscular action causes the medial condyle, dragging with it the meniscus, to travel 

 backward and medialward, thus producing an internal rotation of the thigh on the leg. When 

 the position of full extension is reached the lateral part of the groove on the lateral condyle is 

 pressed against the anterior part of the corresponding meniscus, while the medial part of the 



