Types of Peri-mortem Trauma
Trauma occurring at around the time of death is of great interest to forensic anthropologists. Traumatic injuries to the skeleton are categorised into three broad types, including blunt force trauma, sharp force trauma and projectile trauma. The defining characteristics of each type of trauma are discussed below.
Sharp Force Trauma
- Involves the application of force using a tool, such as a knife.
- Fracture edges are usually smooth, sometimes even shiny, often with small striations produced from the weapon used.
- Angle of the fractures is usually oblique.
- Certain tools can leave distinctive cut marks on the bone, which can then be analysed to assess the implements used.
Massive sharp force trauma to the back of the skull.
Ante-mortem trauma to the skull that has undergone substantial healing.
Blunt Force Trauma
- Involves the application of force of relatively low speed over a comparatively large surface area and can occur due to a fall from height or blow from an object.
- When blunt force trauma occurs on the cranium, it is often surrounded by concentric and radiating fracture lines (a bit like a spider’s web).
- Bone flakes can sometimes adhere to the fractured edges.
- Blunt force trauma result in a tool impression if a weapon was used.
- The application of force through compression of the neck as in strangulation, or hanging, resulting in fractures to the hyoid bone or cervical vertebrae respectively, are also a form of blunt trauma.
- Trauma caused by arrows are also categorised as blunt force trauma rather than projectile trauma.
A skull from the Regional Forensic Center of Knoxville, showing the concentric fracture lines associated with blunt force trauma.
High-Velocity Projectile Trauma
This describes the rapid application of force to a small surface area and often refers to gunshot trauma.
- Entry wounds are usually round or keyhole in shape depending on angle of impact.
- Will result in bevelling (the removal of bone in the path of the projectile).
- Entrance wounds have internal bevelling whereas exit wounds will have external bevelling.
- Can result in radiating and concentric fractures (similar to blunt force trauma).
- Because of the size of the force, high-velocity projectile trauma can result in a greater degree of fracturing and fragmentation of the bone.
An entrance wound caused by high-velocity projectile trauma. Note the fine radiating fracture lines extending from the hole.
An exit wound caused by high-velocity projectile trauma. Note that the injury is larger than the entrance wound and has produced bevelling on the outer surface of the skull.
Forensic anthropologists can provide opinions regarding skeletal injuries based on patterns of trauma observed. As well as the type of trauma, it is also important to consider the location of the trauma on the skeleton. This can help determine whether the injury occurred from an accident or as a result of violence from another person. For example, injuries to the left side of the skull or face are more often produced from a face-to-face attack from a right-handed aggressor. The forensic anthropologist does not determine the cause of death or the manner to death (the way someone died), as this is the responsibility of the medico-legal authorities.
Now that you’ve learned a bit about the various types of trauma, practice some of your new skills with the 3D models provided below in the ‘SEE ALSO’ section. Then confer with your colleagues in the discussion.
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