[Observations on injuries by blunt objects].

Based on my personal experience publishing case reports on blunt injuries, I hereby focus on issues that have recently come to my attention. 1. Abrasions: 1) As to whether they occurred ante-mortem or post-mortem; those reddish in color cannot always have occurred antemortem. When they overlap with reddish (-purple) discoloration, as in hypostasis, post-mortem abrasions look reddish as well. Abrasions larger than the tip of the finger or the palm of the hand are often seen post-mortem and are thought to occur due to the touching of putrefied skin post-mortem. 2) There are cases where the direction in which the epidermis peeled-off is not apparent, when it peels off in many directions or where there is no residual epidermis. 3) The shape and size of an abrasion can indicate the structure of the offending blunt object. When there is an abrasion on the scalp 3 to 4 cm in diameter, with structures 5 mm in diameter at the margins of the abrasion, it can be inferred that the victim fell on a paved gravel road. 2. Bruises: 1) Inferring the nature of a blunt object: (1) Evidence of a fist blow: Co-existence of the following three features indicates a blow by the fist : 1. macular discoloration, 2. within an area of approximately 8 cm by 5 cm, 3. with an abrasion from the thumb nail. (2) Evidence of being grabbed:Try to grab the corpse with your own hand during autopsy to find how the person was grabbed. Bruise-like discoloration can be generated post-mortem on the upper arm, when a body is being drawn out of water, for example. 2) Tram-line bruises: These appear when a victim was struck by a stick. To estimate the diameter of the object, it is useful to measure two parts of the bruising : the width of the pale part between the bruises and the width between the outer margins of the bruises. 3. Intradermal bleeding: There tends to be a grouping of hemorrhagic spots, the interval between which 1 mm or less. It can be generated by both direct and indirect force. Abrasions may be both present or absent. 4. Contused lacerated wounds: First of all, it is necessary to determine the characteristics of the offending blunt object based on the findings of the wound. When the edge of the end of a column works against the skin at an angle, abrasions are mainly generated on the one margin abraded by the edge. When the smooth round surface of a column is applied, abrasions are not likely to occur on or near the margins. To diagnose a wound as being contused, the following findings are considered valuable : the margins of the wound are more irregular than the incision; the margins are contused; the osseous membrane is detached at the bottom of the wound; and abrasions are present at the margins. Abrasions are generated when the surface of the object is rough and when the sharper edge is at an angle. They tend not to occur when the surface of the object is smooth with no angular edge or when the sharper edge works perpendicularly against the skin. 5. Post-mortem mutilation by animals: It is necessary to distinguish wounds caused by animals from those that are man-made. Crows will tear out the eyeballs, open the intercostal muscle and devour the lungs. They pull and rip off the skin, but do not seem to chew on the bones. Dogs and foxes will chew on the bones, leaving traces of their teeth about 5 mm in width. Rats leave round-shaped parts missing from the skin, the margins of which are quite sharp. They do not seem to chew on the bones. 6. One pattern of injuries from an immersed body: A set of abrasions, bruises, pocket formation (décollement) of the head and face, accompanied by dehiscence or fracture of the spine and drowning indicates jumping into the water face first and banging the head against the bottom of the body of the water, followed by drowning. 7. A case of a traffic accident: The details of the accident became apparent from the following findings in and on the autopsied body: contused lacerations on both knees, abrasions and pocket formation (décollement) on the parietal region of the head, characteristically shaped abrasions on the back, acetabula fractures caused by raising of the femoral head, fractured ribs caused by antero-posterior or posteroanterior compression, and an annular fracture at the base of the skull. The abrasions on the back were determined to have been generated by compression of structures on the underside of the car. The contused lacerations on the knees were considered to have been generated upon impact with the bumper, and the posture of the victim was concluded to have been supine with his knees drawn up. Collaboration with police traffic investigators is considered essential. 8. The medico-legal diagnostic capability of young pathologists could be improved if they observed unexplainable findings during autopsy with their own eyes, researched and discussed the findings with their mentor and colleagues, and published case reports.