4 THE SURGICAL ANATOMY OF THE HORSE 



joint is a filling up of this depression. The external lateral ligament of 

 the stifle will be found to take a course downwards to the head of the 

 fibula, which will be felt as a slight hard elevation at a distance of one 

 inch below the femoro-tibial articulation. The three straight ligaments 

 are felt below the patella running to their attachments into the anterior 

 tuberosity of the tibia. 



In front of the head of the fibula is a powerful tendon, which if 

 followed upwards will be found to be inserted between the outer 

 condyle of the femur and the external lip of the trochlea. This is the 

 tendon which is common to the extensor pedis muscle and the tendinous 

 or superficial portion of the flexor metatarsi. The tendon is succeeded 

 by a prominent belly, which forms a well-marked and rounded elevation 

 at the front of the tibial region. This elevation is due chiefly to the 

 underlying extensor pedis muscle, deeply seated to which is the flexor 

 metatarsi. The outline of the extensor pedis is easily visible, since it 

 forms a prominent surface marking, and manipulation is not necessary to 

 define it. 



Running in a vertical direction parallel to the elevation formed by 

 the extensor pedis is another elevation which indicates the course of the 

 peroneus muscle. This muscle arises from the external lateral ligament 

 of the stifle, from the head of the fibula, and the aponeurotic septum 

 between it and the deep flexor of the digit. 



The elevation formed by the peroneus muscle is not so prominent as 

 is that formed by the extensor pedis, as its belly is much less bulky and 

 is not so well developed. The surface of the extensor pedis is convex in 

 the longitudinal direction and markedly so from side to side, whereas the 

 surface of the peroneus is much more flattened. 



Between the two elevations just described is a vertical depression into 

 which the anterior tibial nerve dips. This nerve may be distinctly 

 felt as it crosses the outer surface of the peroneus muscle obliquely prior 

 to its disappearing between the two muscles. A little lower down the 

 musculo-cutaneous branch of the anterior tibial nerve crosses the 



