154 TOPOGRAPHICAL ANATOMY OF 



is indifferent, the joint, in virtue of the character and number of its 

 ligaments, is of considerable strength. 



Before examining the joint itself the dissector should obtain 

 specimens of the bones that form it and study the articular surfaces. 

 If he does this, he will observe that, though the articular face of the 

 patella is, in general, the reverse of the patellar surface of the femur, 

 the opposed surfaces are not capable of accurate and complete applica- 

 tion. Nor is the transverse diameter of the patella equal to that of the 

 patellar surface of the femur. In the recent and unmacerated bone, 

 however, a complementary piece of cartilage is attached to the medial 

 angle of the base of the patella, and moulded upon the large medial lip 

 of the pulley-shaped patellar surface of the femur. If the dissector 

 glides the patella over the patellar surface of the femur he will find 

 that different portions of the one come into successive contact with 

 different portions of the other. 



The condyles of the tibia are very ill-adapted for the reception of 

 the condyle's of the femur: the opposed bony surfaces are decidedly 

 incongruent. 



Dissection. — Remove the remains of the muscles about the joint, but 

 leave the tendons of origin of the popliteus, long extensor, and perongeus 

 tertius muscles. Clean the surface of the joint-capsules, and define the 

 collateral and patellar ligaments. 



The Femoro-patellar 1 articulation (articulatio femoro-patellaris). 

 — The joint-capsule (capsula articularis) is roomy, and attached, on the 

 one hand, to the margin of the articular surface of the patella and, on 

 the other, to the femur along a line about 2 or 3 cm. from the edge of 

 the patellar surface. The distal part of the capsule meets that of the 

 femoro-tibial joint, and, generally, the two joint cavities communicate 

 with each other by one or, possibly, two narrow slit-like openings. In 

 the region where the two capsules meet there is a considerable accumu- 

 lation of fat. The proximal part of the femoro-patellar capsule is pro- 

 longed beyond the base of the patella, as a tri-locular diverticulum, 

 between the extensor quadriceps muscle and the anterior surface of the 

 femur, a pad of fat separating the muscle from the capsule. 



The femoro-patellar ligaments (ligamenta femoro-patellaris), medial 

 and lateral, may be regarded as thickenings of the joint-capsule, with 

 which they are most intimately connected. The lateral band is the 

 stronger, and passes from the femur to the lateral angle of the base 

 of the patella. The weaker medial ligament also has one extremity 

 attached to the femur, the other being connected with the cartilaginous 

 extension of the patella. 



1 Patella [L.], dim. of patina ox patera, a pan, dish, or plate. 



