ARTICULAR SURFACES IN THE KNEE-JOINT. 219 



The posterior or ascending band (d), thicker and stronger than the posterior 

 other, springs from the back of the outer nbro-cartilage, and is 

 inserted into the femur, either as a single band (fig. 83, d\ when 

 it i.s generally in front of the posterior crucial, or as two bands 

 one being before, and the other behind that ligament. 



/'><?. The fibro-cartilages deepen the sockets of the tibia for the Useof fibro- 

 reivption of the condyles of the femur, and fill the interval between cartila es ' 

 the articular surfaces of the bones at the circumference of the joint ; 

 they distribute the pressure of one bone on the other over a larger 

 surface, and cause the force of shocks to be diminished in transmis- 

 sion. In flexion and extension they move forwards and backwards in flexion 

 with the tibia over the femoral condyles. During flexion they s] c n ex 

 recede somewhat from the fore part of the joint, and surround the 

 narrow parts of the condyles ; but in extension they are flattened 

 out on the surface of the tibia. Of the two cartilages, the external 

 moves the most in consequence of its being less attached to the 

 capsule. 



In rotation the fibro-cartilages follow the condyles of the femur, and in rota- 

 and glide over the tibial articular surfaces, the external moving tion : 

 more than the internal. 



The accessory bands in front and behind serve to retain in place use of 

 the less fixed external fibro-cartilage ; thus the anterior ligament ban^s. 01 " 3 

 keeps forwards the front of that cartilage in flexion, and the posterior 

 .-cures the back of the same from displacement in rotation. 



Articular surfaces of the bones. The end of the femur is marked Surfaces of 

 by a patellar and two tibial surfaces. 



The patellar is placed in the middle above the others ; it is on femur, 

 hollowed along the centre, with a slanting surface on each side, the P atellar 

 outer being much the larger of the two. 



The surfaces for contact with the tibia, two in number, occupy and tibial : 

 the ends of the coudyles, and are separated from the patellar im- characters 

 pression by an oblique groove on each side. At the lower part of of 

 each is a somewhat flattened surface, which is in contact with the 

 tibia in standing ; while behind there is a more convex portion, 

 which touches the tibia in flexion. 



The inner condyle of the femur is curved in its anterior third, peculiarities 

 the concavity being directed outwards and backwards; this has ofinner> 

 been named the "oblique curvature." Along the concave margin 

 of the curve is a semilunar facet, which touches the perpendicular 

 surface of the patella in extreme flexion. 



On the head of the tibia are two slight articular hollows, the Articular 

 inner being the deeper and larger, which rise towards the middle tn^ 01 

 of the bone, on the points of the tibial spine. 



The joint-surface of the patella has the following marks. Close Subdivision 

 to the inner edge is a narrow perpendicular facet, and along the ^^J^f 

 lower border is a similar transverse mark. Occupying the rest of patella, 

 the bone is a squarish surface, which is subdivided by a vertical and 

 1 1\ two transverse lines into three pairs of facets upper, middle, and 

 lower. The transverse lines are fainter than the vertical. 



Movements of the joint. The chief movements of the knee are two Kinds of "3 



movement. 



