58 THE SURGICAL ANATOMY OF THE HORSE 



done if the patient be already down, but if not, it is scarcely worth 

 while running the risk, of further complications by endeavouring to cast 

 him. A pitch plaster or charge should be applied to the affected 

 quarter. 



THE PATELLA 



This small bone is placed at the front of the stifle joint. It is a 

 floating bone and is not weight-bearing, its function being to give 

 increased power to the quadriceps extensor cruris muscle. This tendon 

 is inserted into the anterior straight ligaments of the patella which are 

 attached to the anterior face of the bone, and the action of the muscle 

 named is transmitted to the limb through the medium of these ligaments. 

 The patella presents for description three surfaces, of which the 

 anterior surface is the most extensive. This surface is slightly convex in 

 all directions, and is rough for the attachment of the femoro-patellar 

 straight ligaments and also for the attachment of muscles. The posterior 

 surface is entirely articular, and is moulded on to the articular surface of 

 the trochlea. To be accommodated in the vertical groove of the latter, 

 therefore, we find on the patella a vertical ridge, and this separates two 

 areas which are moulded, though not very accurately, on the trochlear 

 ridges. The outer of these areas is broadest superiorly, and tapers towards 

 the inferior border of the bone. The inner area is triangular in outline, 

 the base of the triangle being directed towards the articular ridge and 

 the apex towards the inner border of the bone where the bone appears 

 to be drawn out to a point. This feature enables the observer to 

 distinguish readily between the patella of the right limb and that of 

 the left. 



Of the three surfaces the superior is the least extensive. It is non- 

 articular and roughened. In the antero-posterior direction it is concave, 

 whilst from side to side it presents a slight degree of convexity. 



The patella develops from one centre of ossification. 



