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 

 betwe(Mi the trochlea of the fenuir 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 upper part, which is wide and rounded. The outer 



Proximal part of fctnoro-patellar capisule 

 \ 

 \ 

 \ 



E.iicr nal Jem oro-po tellar 

 ligament 



Middle patellar ligament 



Didal part of femoro- 

 patellar capsule 

 Tendon of origin of long ex- 

 tensor and peroneus tertius 



Pouch of femoro-tibial 

 capsule 



- Femoro-tibial capsule 



_ External lateral ligament 



- Semilunar cartilage 



fA-- External condyle of tibia 



Fig. 156. — Left Stifle Joint of Horse, I^ateral 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 i)atellu is nuich sniall(T than that of the trochlt^a. It is completed internally 

 by a supplementary plate of fibro-cartilage (Fibrocartilago patellse), 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 ridge, 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, 



