194 



THE ARTICULATIONS OF THE HORSE 



THE STIFLE JOINT 



This joint (Articulatio genu), which corresponds to the knee-joint of man, 

 is the largest and most elaborate of all the articulations. Taken as a whole, it 

 may be classed as a ginglymus, although it is not a typical example of the group. 

 In reality it consists of two joints — the femoro-patellar and the femoro-tibial. 



The femoro-patellar articulation (Articulatio femoro-patellaris) is formed 

 between the trochlea of the femur and the articular surface of the patella. 



Articular Surfaces. — The trochlea consists of two slightly oblique ridges, 

 with a wide and deep groove between them. The inner ridge is much the larger 

 of the two, especially at its u]:)per part, which is wide and rounded. The outer 



Proximal part of femoro-patellar capsule 

 \ 

 \ 



Patella — 



Middle patellar ligament 



Distal part of femoro- 

 patellar capsule 



Tendon of origin of long ex- .. 

 tensor and peroneus teriius 



Pouch of femoro-tibial 



capsule 



Exiermd femoro-patellar 

 ligament 



Femoro-tibial capsule 



3y _ External hdcrtd. ligament 

 .^^ ~[ -. Se77iilu7iar cartilage 



External condyle of tibia 



Fig. 156. — Left Stifle Joint op Horse, IjAteral View. 

 The capsules are distended and the external patellar ligament is removed. 



ridge is much narrower, and is more regularly curved; its upper part lies about 

 an inch behind a frontal plane tangent to the inner ridge. The articular surface 

 of the patella is much smaller than that of the trochlea. It is completed internally 

 by a supplementary plate of fibro-cartilage (Fibrocartilago patellae), which curves 

 over the internal surface of the inner lip of the trochlea. A narrow strip of cartilage 

 is found along the outer border also. The articular cartilage on the trochlea 

 completely covers both surfaces of the inner ridg(>, but only a narrow marginal area 

 on the external surface of the outer ridge. 



Joint Capsule. — This is thin and is very capacious. On the patella it is 

 attached around the margin of the articular surface, but on the femur the line of 

 attachment is at a varying distance from the articular surface. On the inner side 

 it is an inch or more from the articular cartilage; on the outer side and above, 



