442 



THE INFERIOR EXTREMITY 



from the tibial tuberosity, whether the knee-joint is flexed or 

 extended. In extension of the knee-joint, the distal part of 

 the articular surface of the patella is in contact with the 

 proximal part of the trochlea (Fig. 131), but,, when the joint is 

 flexed, the patella is drawn downwards by its ligament so that 

 its articular surface is more fully in contact with the femur. 



Vastus lateral 



\ \ I 



"V astus medialis 

 Quadriceps tendon 

 Adductor tubercle 



Depression over latera 

 meniscus' 



Head of fibula 



Depression over medial 

 meniscus 



Ligamentum patellae 



Tibial tuberosity 



FIG. 127. Surface Landmarks in the Region of the Knee. 



When the knee is passively extended the patella may be 

 moved from side to side, and, owing to the elasticity of the 

 quadriceps muscle, it may be pushed distally. When the joint 

 is distended with fluid the articular surfaces of the patella 

 and the femur are separated from one another. This condition 

 is termed " floating patella," and, when the patella is gently 

 tapped, it may be made to knock against the femur. 



The ligamentum patella can be traced from the apex of the 

 patella to the tibial tuberosity. It is about two inches long and 



