638 



DISSECTION OF THE LEG. 



Fig. 219. 



received their name from that circumstance. One is much anterior to 

 the other at the attachment to the tibia. 



The anterior ligament (/) is most oblique in its direction, and is smaller 

 than the posterior. Inferiorly it is attached in front of the spine of the 

 tibia, close to the inner articular surface, reaching back to the inner point 

 of the spine: superiorly it is inserted by its posterior shorter fibres into 

 the back of the outer condyle of the femur, and by the anterior or longer 

 into the hinder part of the intercondyloid fossa. 



The posterior ligament (<?) is almost vertical between the bones at the 

 back of the joint. By the lower end it is fixed to the hindermost impres- 

 sion of the hollow behind the spine of the 

 tibia, near the margin of the bone; and 

 above its posterior shorter fibres are in- 

 serted into the inner condyle along the side 

 of the oblique curve, whilst the anterior 

 and longer reach the fore part of the inter- 

 condyloid fossa. 



The use of these ligaments in the move- 

 ments of the joint, after the external liga- 

 ments have been cut through may now be 

 studied. 



As long as both ligaments are whole the 

 bones cannot be separated from each other. 

 Rotation in of the tibia is stopped by 

 the anterior crucial. Rotation out is not 

 checked by either ligament ; for the bands 

 uncross in the execution of the movement, 

 and will permit the tibia to be put hind 

 foremost. 



Supposing the tibia to move, as in 

 straightening the limb, the anterior, pre- 

 vents that bone being carried too far for- 

 wards by the extensor tendon, or by force ; 

 and the ligament is brought into action at 

 the end of extension, because the tibia is 

 being put in front of the femur. Its use is 

 shown by cutting it across, and leaving the 

 posterior entire, as then the tibial articulat- 

 ing surfaces can be placed in front of the 

 femoral in the half bent state of the joint. 

 The posterior crucial arrests the too 

 great movements backwards of the tibia by 

 the flexors or by force ; and it is stretched 

 in extreme flexion, in which the tibia is being drawn back from the femur. 

 This use will be exemplified by cutting across the posterior (in another 

 joint or in another dissection) and leaving entire the anterior : when this 

 has been done the articular surfaces of the tibia can be carried nearly 

 altogether behind the condyles of the femur. 



The interarticidar or semilunar fibro-cartilages (fig. 220) cover partly 

 on each side the articular surface of the tibia. 



They are thick at the outer margin, where they are united by fibres to 

 the capsule, and are thin at the inner edge ; they are hollowed on the 

 upper surface, so as to assist in giving depth to the fossce for the reception 



INTEKARTICULAR LIGAMENTS OF THE 

 KNEE-JOINT. 



a. Internal, and 



b. External semilunar flbro-cartilage ; 



the latter rather displaced by the 



bending of the joint. 

 e. Posterior crucial ligament, with d, 



the ascending ligamentous band 



of the external flbro-cartilage. 

 /. Anterior crucial ligament. 

 g. Patellar surface of the femur. 



