422 



THE ANATOMY OF THE HORSE 



car('d<i(/r. is nearly of a semi-circular form ; larger and thinner than the 

 external, it is inserted by its anterior extremity to an excavation in front 

 of the tibial spine, and by its posterior extremity to a little pit behind the 

 spine : it is in close relation with the posterior crucial ligaments. The 

 external semilunar cartilage fixes itself in front, near the anterior insertion 

 of the opposite fibro-cartilage : its posterior extremity gives off two cords, 

 one superior, the other inferior. The former, Avhich is the longer and 

 stronger of the two, is attached to the fossa at 

 the back of the space between the condyles. The 

 latter, thinner and broader, is spread out upon the 

 posterior edge of the external tibial articulating 

 surface. 



The synovial memhrane lines the contiguous sur- 

 faces of the pai'ts entei'ing into the composition of 

 tlie stifle joint. Commencing to trace the reflections 

 of this membrane at the boi-der of the patella, it 

 will be found to line the capsule, but below that 

 bone it is separated from the anterior ligaments by 

 a considerable quantity of adipose tissue, which pro- 

 longs itself to the inter-condyloid hollow, where it 

 is attached ; from this it is reflected over the semi- 

 lunar cartilages, around the crucial ligaments, and 

 forms a partial covering for them, inclosing them 

 as far as their attachments. At the sides of the 

 patella it forms two slight folds, the ligamenta alaria. 

 Finally it ascends in front of the femur, and passes 

 downward to the margin of the patella. 



The lifjaments are, fix'st, those which unite the 

 femur to the tibia, consisting of the lateral, the 

 crucial, the posterior, the transverse, and the cap- 

 sular ; and, secondly, those uniting the patella to 

 the tibia, which are three, an external, a middle, 

 and an internal. 



1. The lateral liyaments are fibrous bands, situ- 

 ated on the sides of the articulation, more behind 

 than in front ; they become relaxed during flexion, 

 and hold the bones strongly together during exten- 

 sion. The External, a rounded, cord-like fasciculus 

 of fibres (the longer and stronger) passes from the tuberosity of the external 

 condyle of the femur to the head of the fibula; its direction is almost 

 vertical. The Internal, broad and flat, connects the tuberosity of the in- 

 ternal condyle of the femur with the upper and inner edge of the tuberosity 

 of the tibia. It adheres to the internal semilunar cartilage. 



The crucial or interosseous ligaments are placed at the posterior part of 

 the joint, external to the synovial membrane, but partially invested by it. 

 Their direction is oblique, so that they cross or decussate somewhat like 

 the letter X. One is named the anterior, the other the posterior. The 

 Anterior is fixed by its inferior extremity to the groove formed on the 

 summit of the tibial spine, and by its superior extremity to the inter- 

 condyloid hollow, and to the inner part of the external condyle. The 



Fig. 56.— Posterior View of 

 Stifle Joint. 



A. Inferior third, of femur. 



15. B. Condyles. 



I). Superior third of the tibin. 



E. Fibula. 



F. Patella. 



1. Internal lateral ligament of 



the patella. 



2. External lateral ligament of 



the femoio-tibial articu- 

 lation. 



3. Internal lateral ligament of 



the femoro-tibial articu- 

 lation. 



4. Posterior crucial ligament. 



5. 5. Semilunar cartilages. 



