#perimortem

Week Eight: Tuesday, March 5, 2019

This week’s lecture on subfields of biological anthropology the focus was on forensic anthropology, which is the use of human osteology and archaeology to legal investigation of human remains. A large point of focus was trauma; the different aspects of trauma, the nature of trauma, the importance of the location and pattern of trauma and so forth. We also spoke briefly about forensic entomology or the use of insects and other bug activity in a body to determine time of death.

In relation to the nature of trauma, we talked about the three different time classifications used to describe the time in which an injury or trauma was sustained by the victim. First, there was an antemortem trauma which is an injury that occurred sometime before the victim’s death and therefore an anthropologist would be able to clearly see remodeling on the bone. Second, there was a perimortem trauma which is an injury that occurred right before the death of the victim and could possibly also serve as cause of death. Some characteristics of a perimortem trauma include sharp edges surrounding the injury, hinging, fracture lines, and hematoma staining. The final one was postmortem trauma which is an injury that occurred after the victim had already died, an example of this would be cut marks on the bone of a victim that was dismembered by their killer. Some characteristics of a postmortem trauma include clean edged wounds, no hinging, and very little evidence of fracture lines.

Hey Nonnie,

Before we start, lets have some basic definitions.Antemortem injuries occurs before death, it is usually indicated by signs ofhealing. Perimortem injuries are those that occur at or near the time of death,with no evidence of healing. Postmortem injuries occur after death, also withno evidence of healing.

Differentiating between the types/timeline of injuries ismainly studied in the field of forensic anthropology, dealing with skeletaltrauma.

The healing process of injuries happens almost immediatelyafter it occurs. Evidence of the healing process on skeletal fractures can showas early as after 1 week after the injury. Between week 1 and 3, the fracture edgeswill remold and rounded, and by week 6 a bony callus will form. Healing rateswill of course depends on facts such as overall health and nutritional statusof the person injured. Anthropologist can use bones to basically figure outhistory trauma on the body: history of abuse or accidental trauma, history ofnutrition, indication of poverty etc. Fun fact, antemortem injuries/fracturescan help with confirming identity of an unknown person through presence ofplates/pins (which might have serial numbers recorded in medial charts).

Perimortem trauma is important for reconstructing the eventsthat occurs near the time of death, while postmortem trauma is important todetermine if the injuries are caused to conceal some information about thecrime (or from opportunistic local wildlife feasting on free food). With perimortemfractures, the person died before healing take place, but the fracture shouldstill show signs of the biomechanics of healing starting similar to antemortemfractures. Peri- and post-mortem trauma is different from antemortem traumasince there is no sign of healing. Bones are elastic while alive, and gets dryand brittle after death in a process called plastic deformation. This means thatperimortem bone fractures tends to splinter, while postertem breaks shatter ina more regular shape.

Moving away from bones and onto bruising. Bruises is adiscolouration of the skin when blood vessels/capillaries are damaged bytrauma, letting seeps/hemorrhage. Since bruises accompanies different types ofwounds, usually associated with blunt trauma, so they can provide informationon their causation and help with the reconstruction of events leading up todeath. Bruises are dated/aged differently depending on where it is on the body.A deep bruise in the thigh muscle might not appear for a day or two, while abruise over a bony prominence and where tissue is loose (ie near the eyes) willappear and swell very quickly. Postmortem injuries tend to have a yellowishbrown, kind of bloodless appearance, lacking vital reaction due to the absenceof blood flow after death.

a man named Tim known by all his friends as a huge Paramore fan: Paramore Tim