MEDICO-LEGAL ASPECTS OF
Physical Injury is the effect of some forms of stimulus on the body. The effect may only be apparent when the stimulus applied is insufficient to cause injury and the body resistance is great. It may be real when the effect is visible. The effect of the application of stimulus may be immediate or may be delayed. A thrust to the body of a sharp pointed and sharp edged instrument will lead to the immediate production of a stab wound, while a hit by a blunt object may cause the delayed production of a contusion. Causes of Physical Injuries:
A. Physical Violence
B. Heat or Cold
C. Electrical Energy
D. Chemical Energy
E. Radiation by Radio-Active Substances
F. Change of Atmospheric Pressure (Barotrauma)
PHYSICAL INJURIES BROUGHT ABOUT
BY PHYSICAL VIOLENCE
The effect of the application of physical violence on a person is the production of wound.
A wound is the solution of the natural continuity of any tissue of the living body. It is the disruption of the anatomic integrity of a tissue of a body. In several occasions, the word physical injury is used interchangeably with wound. However, the effect of the physical violence may not always result to the production of wound, but the wound is always the effect of physical violence. Physics of Wound Production:
Wound = Kinetic energy X time X area X “other factors”
MVM = MassV = Velocity
Kinetic Energy = -------
Inasmuch as kinetic energy is based on the mass and velocity factors and that the velocity is squared, the velocity component is the important factor. This explains why an M-16 bullet which has a speed or 3,200 ft/sec. will do more damage than a 0.38 caliber bullet which is heavier but has a much slower velocity. Time:
The shorter the period of time needed for the transfer of energy, the greater the likelihood of producing damage. If a person is hit on the body and the body moves toward the direction of the force applied, the injury is less as when the body id stationary. Area of Transfer:
The larger the area of contact between the forces applied on the body, the lesser is the damage to the body. By applying an equal force, the damage caused by stabbing is greater compared to a blunt instrument. “Other Factors”
The less elastic and plastic the tissue, the greater the likelihood that a laceration will result. Elasticity and plasticity refers to the ability of a tissue to return to its “normal” size and shape after being deformed by a pressure.
The movement of the parts of the body as a result of the force being applied to them and the local stretching of tissue during acceleration and deceleration cause most of the internal injuries seen in traumatized individuals.
A force transmitted through a tissue containing fluid will force the fluid away from the area of contact in all directions equally, frequently causing the tissue to lacerate (Legal Medicine Annual 1980, Cyril Wecht ed., p. 36). Vital Reactions:
It is the sum total of all reactions of tissue or organ to trauma. The reaction may be observed macroscopically and microscopically.
The following are the common reactions of a living tissue to trauma: a. “Rubor” – Redness or congestion of the area due to an increase of blood supply as a part of the reparative mechanism. b. “Calor” – Sensation of heat or increase in temperature. c. “Dolor” – Pain on account of the involvement of the sensory nerve. d. “Loss of Function” – On account of the trauma, the tissue may not be able to function normally. The presence of the vital reaction differentiates an ante-mortem from a post-mortem injury. In the following instances vital reactions or changes may not be observed even if injury was inflicted during life: a. If physical injuries are inflicted during the agonal state of a living person. The body cells or tissue during the period may no longer have the...