Fig. 177. Sagittal Section through the Knee-joint during Extension. 



Frozen Section ilirough the External Condyle of the Femur and the Tibia; the 

 Patella is not cut along its greatest longitudinal axis. 



The Knee-joint is easily accessible from in front or either side, onl)' on 

 its posterior surface, do we find large muscles and between them important Nerves 

 and Vessels. This Synovial Cavity is the largest in the body; moreover, it is the 

 most complex joint on account of its various Intrinsic Ligaments. 



The insertion of the Capsule is different on all sides. The joint-cavity 

 extends highest in front, as far as 1^/4 to 2V4 inch, above the margin of the 

 Patella, if we take into account the Subcrureal Bursa, which nearly always com- 

 municates with the Joint. On both sides (cf . Fig. 1 80), the insertion of the Capsule 

 reaches close to the line of the joint, posteriorly, it extends upwards as far as the 

 upper limit of the Condyles of the Femur, below it follows the Tibia to a lesser 

 extent. Thus the anterior and posterior surfaces of the Femoral Condyles are 

 within the Synovial Sac, but not so their lateral surfaces. 



The anterior wall of the Capsule is formed above by the Tendon of the 

 Quadriceps; between this tendon and the anterior surface of the Femur there is 

 always a Bursa which is of importance because it communicates, occasionally in 

 children, but invariably in adults (98 %)' by a more or less wide opening (cf. course 

 of a director in the figure), with the Joint-Cavity. This Bursa may, therefore, be 

 regarded as a part of the Joint-Cavity, and be called tlie upper cul-de-sac of the 

 Knee-joint. Accumulations of fluid within the Knee-joint cause bulging at this 

 spot. Below the point of insertion of the Quadriceps Extensor to the upper 

 border of the Patella, the wall of the joint is formed by the cartilaginous covering 

 of the posterior surface of this bone. The Ligamentum Patellae attaches the lower 

 border of this bone to the Tubercle of the Tibia. Between it and the Tibia lies 

 the deep Infra-patellar Bursa which does not communicate with the Joint on 

 account of its being separated by a large Synovial-fold — Plica Synovialis Patellaris. 

 This is attached to the Intercondylar Fossa (Crucial Ligaments) by sagittal fibres. 



Between the Tibia and the Femur, the External Semilunar Cartilage is 

 seen in the figure, its inner concave margin is sharp, its external convex margin 

 is firmly connected with the capsule of the joint. 



