48 THE SURGICAL ANATOMY OF THE HORSE 



rushing through gateways. It has already been remarked that this 

 angle is one of the prominent points which come into contact with the 

 ground when the animal falls on its broadside. Falling in such manner 

 on a hard road or pavement frequently results in fracture, or it might 

 be the result of a blow, as also may be fracture of the internal angle. 

 As already stated, this latter angle is the highest point of the body in the 

 region of the croup. In colliery ponies it is frequently fractured by 

 falling spars, by a fall of the roof or by " roofing " whilst going down an 

 incline, when, owing to the extended position of the fore limbs, the fore 

 part of the body is depressed in such a manner that the croup becomes 

 the highest part of the body, and is therefore the most likely to come 

 into contact with the supporting spars of the roof. Other fractures 

 may be due to violent muscular contraction. These are most com- 

 monly met with in old animals in which the bones are more brittle. 

 Fracture along or parallel to the symphysis may be caused by the two 

 hind legs slipping outwards and thus being violently and simultaneously 

 abducted. The effect of this is to throw enormous and sudden tension 

 on the adductor muscles, which are attached to these bones near the line 

 of fracture. Fracture through the acetabulum may result from a severe 

 blow received over the great trochanter of the femur, when the articular 

 head of this bone becomes forcibly driven into the cotyloid cavity and 

 we have fracture with, usually, some internal displacement. Similarly, 

 fracture of the tuber ischii may result from a blow, and is by no means 

 an uncommon result of a kick from another animal. 



In colliery ponies, again, the expanded portion of the ilium is not 

 infrequently smashed by a fall of the roof on to the quarter. Fracture 

 of some part of the innominate bone at times also results from casting on 

 hard ground or struggling violently when secured by hobbles. 



Sudden lameness is almost a constant symptom of fractured 

 innominate bone. It will be readily understood, however, that lame- 

 ness varies according to the seat of the fracture and the muscles affected 

 in consequence. 



