310 INFERIOR EXTREMITY 



ARTICULATIONS. 



The dissection of the knee-joint, the ankle-joint, the tibio- 

 fibular joints, and the various articulations of the foot, may 

 now be proceeded with. It is possible that the ligaments may 

 have become hard and dry. If this be the case, soak the 

 joints in water for an hour or two. 



ARTICULATIO GENU (KNEE-JOINT). 



In the knee-joint three bones are in apposition, viz. 

 the distal end of the femur, the proximal end of the 

 tibia, and the patella. It is the largest and most com- 

 plicated articulation in the body ; and, if the bones be 

 examined in the skeleton, the joint presents an apparent 

 insecurity, because the bony surfaces show little adaptation 

 the one to the other. In reality, however, the knee-joint is 

 very strong, and very rarely suffers dislocation on account of 

 the strength of the ligaments which retain the bones in place. 

 The ligaments on the exterior of the joint are : 



1. The capsular ligament. 



2. Two collateral ligaments fibular and tibial. 



3. The ligamentum patellae (or anterior ligament). 



4. The oblique popliteal ligament. 



Dissection. The popliteal vessels, tibial and common peroneal nerves, 

 and the muscles surrounding the knee-joint, must be removed. Portions 

 of the tendons of the biceps femoris, semimembranosus, sartorius, semitendi- 

 nosus, gracilis, and popliteus, together with small pieces of the heads of the 

 gastrocnemius, should be left in place in order that their connections with 

 the ligaments of the joint may be studied. The quadriceps extensor may 

 be divided about three inches proximal to the patella, and the distal part 

 allowed to remain in position. Further, the various genicular arteries 

 which surround the joint should be followed to their terminations. 



Capsula Articularis. The capsule of the knee-joint, 

 together with the tibial collateral ligament and the oblique 

 popliteal ligament, form a complete investment for the joint. 

 In some places the fibrous or peripheral part of the capsule 

 has disappeared and has been replaced either by bone and 

 cartilage or by tendon, and in other places it has been 

 strengthened and extended by the incorporation of adjacent 

 portions of fascia and tendons, thus anteriorly the patella 

 entirely replaces a portion of the capsule and above the 

 patella the capsule is merely represented by the stratum 



