376 Anatomy Applied to Medicine and Surgery. 



an epiphysis and, uniting, as it does, with the shaft, about 

 the age of twenty-five, may be broken off, either by direct 

 blows or by sudden, forcible contraction of the biceps 

 muscle. When this accident occurs there is a possibility 

 of the external popliteal nerve being injured, or of its be- 

 ing included in the resulting callus, with subsequent par- 

 alysis of the muscles supplied by it. Potts' Fracture. 

 Here the fibula breaks at its weakest part, i.e., within two 

 or three inches from the lower extremity. In this fracture, 

 the foot is turned outwards, and the tibia, having lost its 

 support, is forced inwards from off the astragalus, stretch- 

 ing or tearing the internal ligament of the joint, so that, in 

 addition to the fracture, there is a partial dislocation. The 

 foot in this injury is everted, partly from mechanical 

 causes and partly from the action of the peroneus longus ; 

 while the muscles of the calf draw up the heel. Since the 

 greater part of the fibula is buried beneath muscles, and, 

 since the head and the external malleolus, along with 

 about three inches of the external surface of the shaft 

 above the malleolus, are the only parts of the bone that 

 can be clearly felt, it follows, that it is often difficult to 

 recognize a fracture of the shaft of the fibula, especially 

 when swelling has occurred. The fact that pressure on 

 these subcutaneous portions of the bone may elicit pain at 

 the seat of fracture when the shaft is broken, may be of 

 assistance in diagnosis. Fracture of both bones is gener- 

 ally the result of direct blows or of crushing accidents, 

 and out of two hundred and seventeen fractures of both 

 bones, one hundred and twenty-five belonged to the lower 

 third (Hamilton) . Indirect fractures are, as a rule, oblique, 

 the tibia being broken, generally, in a direction downward, 

 forward and inward. Compound fractures are more fre- 

 quent here than in any other of the bones of the body 

 no doubt because of the superficial position of these bones 



