Fist. 92. 



ABTICVLATIOm OF THE POSTERIOR LIMBS. 167 



they will not be detailed here ; but some remarks will be made with regard 

 to the displacement the fibro-cartilages undergo when the articulation is in 

 motion. 



During ^eiBiore and extension, these bodies, fixed on the tibial facets, which 

 they transform into glenoid cavities, 

 move with them on the condyles of the 

 femur, from before to behind, or behind 

 to before, according to the movement 

 executed. But at the same time they 

 also gliile in an inverse direction, and 

 to a very appreciable degree, on the 

 superior extremity of the tibia. There- 

 fore, during ilexion, they pass from 

 behind forward on this extremity, and 

 are drawn backwards during exten- 

 sion. 



In rotation, which may take place 

 from within to without, or from with- 

 out to within, the movement is pro- 

 duced not only by the pivoting of the 

 condyles in their glenoid cavities, but 

 also by a sensible displacement of the 

 meniscii on the tibial surfaces. 



In the Bog and Cat, the meniscii are 

 joined together near their anterior insertion 

 by a transverse fibrous baud. There is only 

 one patellar ligament, and the posterior liga- 

 ment shows in its thickness two email sesa- 

 moid bones against which the condyles of 

 the femur play inwardly, and which give 

 attachment, outwardly, to the origiuaiing 

 branches of the external gastrocnemius mus- 

 cle. There is no femoro-patellar capsule, and 

 only one synovial membrane for the whole 

 articulation. 



In the Pig and Sheep, there is also only 

 one ligament and one synovial capsule. 



4. Tihio-fihular Articulation. 



This articulation represents a small 

 planiform diarthrosis, whose move- 

 ments are very limited and obscure. 

 It is formed by the union of the irre- 

 gular diarthrodial facet which occupies 

 the internal face of the head of the 

 fibula, with the analogous facet on the 

 external superior tuberosity of the 

 tibia. Short and strong interosseous 

 or peripheral fibres envelop these 

 facets on every side, and maintain them 

 firmly in contact. 



The fibula is also attached to the tibia: "1, Above, by two small liga- 

 mentous fasciculi crossed like the letter X, which form the superior part of 

 the great arch through which pass the anterior tibial artery and vein (Fig. 

 .92, 12}; 2, In the middle, by a kind of aponeurotic membrane, whose width 



LIGAMENTS ATTACHINa THK THREE B0NE8 

 OF THE LEG. 



No. 1. Posterior face. — No. 2. Anterior face. 

 - — 1, Complementary fibro-cartilnginous 

 pad of the patellar surface ; 2, External 

 patellar ligament ; 2', Insertion of the long 

 vastus into this ligament ; 3, Internal 

 patellar ligament ; 3', Its upper insertion 

 transformed into a complementary appa- 

 ratus of the patellar surfiice ; 4, Middle 

 patellar ligament; 5, External meniscus 

 of the tibia J 6, Its branch of insertion 

 into the femur cut off at its origm : 7, Its 

 posterior tibial insertion ; 8, External me- 

 niscus ; 9, Insertion of the anterior crucial 

 ligament into the fossa of the tibial spine; 

 10, Tibial insertion of the posterior crucial 

 ligament; 11, Inferior insertion of the ex- 

 ternal femoro-tibial ligament; 12, 13, 14, 

 Tibio-fibular ligaments. — A, Tibial arch; 

 E, Surface of insertion of the popliteus 

 muscle; c, Surface of insertion for the 

 perforans muscle. 



