DISEASES OF BONES ld3 



2. Compoiind : here an open ■wound leads to tlie broken 

 bone. 



Name the varieties of fractures, 



(1) Incomplete, (3) complete, (3) compound. 



Describe incomplete fractures. 



This class is represented by fractures where the continuity 

 of the bone is not entirely lost — that is, the break extends 

 partially through, the thickness of or partially across the bone. 



As incomplete fractures are recognized : 



(a) Fissure or fissured fractures. This consists of a crack 

 or split in the bone. These are quite common in the horse 

 and difiB.cult of diagnosis ; met with usually in the os sufEra- 

 ginis and tibia. 



(&) Green stick fracture. This is a true incomplete frac- 

 ture. It is called "green stick" because the appearance of the 

 injured bone is about the same as when a green stick is held 

 at either end by the hands and broken across the knee, lead- 

 ing to a pulling apart of the fibres on the outside while the> 

 concave portion — that is, the one resting against the knee — 

 is compressed. In the bone, therefore, a portion of its thick- 

 ness is broken while the balance is bent. Only seen in the, 

 long bones and ribs of very young animals. 



(c) Depression fracture : In these a portion of the thick- 

 ness of a bone is crushed. This must not be confounded with 

 a depressed fracture, where the entire thickness of the bone 

 is crushed in. Usually seen about the cranial and facial 

 bones. 



id) Strain fracture : Consists of the breaking off of a 

 piece of a bone, due to violent contraction of a muscle, as, 

 the tearing off of a piece of the os calcis through strain upon 

 it by the gastrocnemii. 



