THE INNOMINATE BONE 49 



Diagnosis of fracture of either of the two angles of the ilium or of the 

 tuber ischii is not diiEcult, since the fractured piece may be readily detected 

 by palpating the part. In cases of fracture of the angle of the haunch 

 or of the expanded portion of the ilium, by observing the animal from 

 behind there will be noticed a marked alteration in the conformation of 

 the affected quarter and a striking difference when the two hind 

 quarters are compared. The prominence caused by the underlying 

 iliac angle will now be found to have disappeared, and the affected 

 quarter is rounded off. The fractured piece of bone is displaced in the 

 downward direction owing to the pull exerted upon it by the tensor 

 vaginas femoris and the abdominal muscles, which are attached to it. 



When fractured, the tuber ischii is similarly subjected to downward 

 displacement owing to the weight of the muscles to which it gives 

 attachment. 



Diagnosis of some of the other fractures is much more difficult. 

 Fracture through the acetabulum may occasionally be detected by 

 pressing on the great trochanter with the palm of the hand, when it 

 will be found that the parts beyond the trochanter have lost their 

 ordinary firm resistance. If the hand be passed along the rectum, or, in 

 the mare, the vagina, and the palmar aspect be directed outwardly 

 fractures through the cotyloid cavity may frequently be felt, particularly 

 if an assistant apply pressure over the great trochanter as indicated 

 above. Of course the observer is always on the alert for crepitation, 

 and in this case it is best to place the ear slightly in front of the summit 

 of the great trochanter of the femur and near the upper border of 

 its convexity. Similar exploration by the rectum or vagina is of utility 

 in diagonising fractured symphysis, fractures of the pubic bone, and 

 fracture behind the antero-external angle of the ischium. Fracture of 

 the OS pubis, in front of the obturator foramen and towards the inferior 

 extremity of the obturator groove, gives rise to a most peculiar lameness, 

 which will be more fully dealt with in the chapter on nerves. (See 

 Obturator Paralysis.) 



