Types of abrasions

    1. Linear abrasions  ( Scratches) :  caused by relative movement of a pointed object on the skin  

                                     eg. nail, thorn, point of sword or knife

    2. Grazed abrasions : caused by relative movement of a rough surface on a wide area of skin.                               

                         eg. falls , a victim being dragged on the ground , road traffic accidents    

    3. Imprint abrasions ( patterned abrasions, crushing abrasion) : caused by the impact of a rigid hard rough surface over a localized area of the skin without any movement                      

                                 eg. fingernail , tyre ,  grills , bicycle chain , bite  marks

    4.Friction abrasions : caused by pressure upon the skin with an agent with a smooth surface accompanied by movement.       

          eg. ligature marks around the neck in hanging, lashes with a whip

                                           Medico legal importance              

• Gives a clue about the direction of trauma

   

• Helps to identify certain features of the causative agent

   

  Imprint of the muzzle of a shotgun (Abrasion ring)

  Imprint of the hilt guard of a knife

• Helps in finding the time of injury         

   A patient presented with a complaint of being assaulted by a neighbour a few hours before admission.

 On examination an abrasion was seen over the elbow.

? Can you corroborate the history given by the patient by dating the injury 

•   May indicate serious internal injury  - eg. grazed abrasion over left upper abdomen may look harmless but may be the only clue to a ruptured spleen                 

•  The pattern of abrasions provide evidence of the nature and the mechanism of trauma.                            

   eg. grazed abrasions in different directions all over exposed areas of the body indicate that a body has been thrown on a rough surface in different directions.

          This suggest a mechanism like a fall down a well or a road traffic accident. 

•  An abrasion can be categorized for medico legal purposes .   

                   ? If an uncomplicated abrasion  seen over the face, is it grievous    

• Helps in reconstructing the incident  eg. finger nail abrasions in strangulation helps in finding the relative position of both victim and the assailant  

• Indicates the type of crime  eg. strangulation, sexual offence etc.    

• Antemortem abrasions need to be differentiated from  postmortem abrasions as postmortem abrasions are common and caused by rough handling of the corpse and/or due to animal bites.

      It is difficult to determine whether friction abrasions are antemortem or post mortem as they becomes stiff, leathery, parched and brownish sometime after death mimicking postmortem injury.