AETHROLOGY. 1 ] 3 



the outer extremity of tlie patella to the supero-external 

 angle of the same ridge. The capsular ligament, after con- 

 necting together the two articulatory surfaces posteriorly 

 and laterally, and internally becoming attached to the 

 semilunar cartilages, externally to the lateral ligaments 

 (partially separated from the outer by the tendon of pop- 

 liteus), blends with the inner and the outer straight 

 ligaments of the patella, connecting them together, and 

 covering the central straigJit ligament, which commences 

 about the centre of the anterior surface of the patella, 

 plays over a bursa on that bone, is separated from the main 

 joint by a quantity of fat, plays over another bursa at the 

 central part of the superior extremity of the tibial ridge, 

 and becomes attached below it. 



The synovial membranes of this joint are two or three in 

 number, for in some cases we see the cavity of the joint 

 between the femur and the patella communicating with that 

 of the inner condyle of the femur. The cavity of the outer 

 condyle always remains distinct. These cavities frequently 

 communicate with the important bursae in the neighbour- 

 hood. The condyles come directly into contact with the la- 

 teral parts of the spine of the tibia, the upper surfaces of the 

 semilunar cartilages are concave 1o accommodate the con- 

 vex surfaces of the condyles, their under surfaces are plane. 



The mode of union of the fibula to the tibia has been 

 already described. 



HOCK JOINT. 



The small bones of the hock, like those of the 

 knee, are united together by interosseous and connectincj 

 ligaments, thus producing two rows, the superior formed 

 by astragalus and calcis, the inferior by the cuboid 

 and three cuneiform bones. These, together with the 

 metatarsus, form the tarsal and tar so -metatarsal gliding 

 joints, lubricated with synovia secreted by membranes, 

 which extend to the facets situated between the several 

 small bones ; generally a distinct synovial sac may be dis- 

 tinguished between the component bony layers of the 

 lower row. 



The true hock-joint is the ginglymoid articulation formed 

 by the apposition of the inferior grooves of the tibia with 

 the superior ridges of astragalus. This joint presents a 

 capsular ligament, attached around the edge of the articu- 



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