Injuries on the chest will be different according to the different circumstances, weapon used and the nature of the injury.
Accidental injuries of road vehicular origin are generally extensive. When it is a case of run over, there may be crushing of the chest with presence of tyre marks. In case of a person simply being knocked down, there will be primary impact injuries, or extensive secondary injuries in the form of extensive grazed abrasion, bruise or laceration. In these circumstances, there will be corresponding gross -internal injuries in the form of subcutaneous haematomas, fracture of clavicles, ribs and sternum at one or more than one place. There may be varying degree injuries to the intra-thoracic structures with or without rib fracture. These may be in the form of contusion or laceration and may involve pleurae, lungs and mediastinal structures, including the heart. The heart may get separated at the base. There may be rupture of the ventricles, but the auricles may be spared. In traffic accident deaths involving the intra-thoracic structures, there is invariably huge accumulation of liquid and clotted blood. In cases, where death occurs late, pneumothorax, pyothorax or haemothorax may be the cause.
Accidental blunt force injury on the chest may occur in some other circumstances also, e.g., fall from a height or getting pressed under a machine, in between buffers of two bogies of a train, or in other traumatic asphyxia circumstances. Crush injuries may be caused when the chest is or under the wheel of a vehicle or compressed in between two rollers of a machine. The type of injuries and the depth of involvement will depend on the force of the impact and the type of the causative agent. The injuries may thus be anything from external abrasion to gross internal injuries.
Homicidal blunt force injuries are comparatively superficial with abrasions, contusions and occasional lacerations on the chest wall. With comparatively heavy force impact, there may be fracture of the sternum, clavicles and ribs, with corresponding internal injuries.
In case of blunt force injuries of the internal organs of the chest, it may often be difficult to assess its extent from outside.
Incised wounds over the chest wall, if reasonably deep and if are chops, go much in support of being homicidal in nature. Chop wounds are exclusively homicidal except in those rare circumstances where these may be accidental in nature. Self-inflicted incised wounds on the chest wall may be fabricated ones and bear the characteristic features of self inflicted incised wounds as seen elsewhere. Deeper incised wounds on unapproachable parts of the chest wall are not suicidal in nature. It is not a necessity that, incised wounds on the chest wall will be superficial in nature. Often their depth may be extended upto the chest cavity, particularly in case of chop wounds. Accidental incised wounds may result from fall on sharp edge of a cutting weapon or object or during operation of a sharp cutting machinery. When a chop wound enters the chest cavity, then the injuries to the internal organs will have similarity with penetrating wounds.
Penetrating wounds of the thorax are very much significant in many ways. Penetrating wound of the chest may give deceiving informations about the length of the blade of the weapon and the direction of the penetration. When from the front, the length of the blade of the weapon may wrongly appear more than what it actually is and the direction of the wound may wrongly appear more upwards, when the lung is injured, due to backward and upward movement of the injured and collapsed lung, due to their posterior and upper attachment. The position is reversed when the stab is from the back and penetrates the lung. The depth or for that purpose the length of the blade of the weapon will appear shorter and the direction of the penetration will appear more upwards, than what it is.
Fatal suicidal stab wounds on the chest are typically located over the precordial area of the anterior chest wall. With one centrally placed deep penetrating wound there may be cluster of superficial tentative stab wounds.
Occasionally, accidental stab wounds may be sustained on the thorax due either to a fall over the pointed projecting part of a weapon or object or accidental penetration of the chest wall by some pointing substance or weapon.
Stab wounds over the auricles, aorta or the superior vena cava shall be immediately fatal whereas the same on the ventricles may not be immediately fatal, and may give sufficient time to undertake operative treatment. Stab wounds on the ventricles particularly on the left ventricle may not be fatal if that does not reach the cavity of the ventricle. Death may not be quick even if the weapon has entered the ventricular cavity, if the direction of the wound is oblique in relation to the wall of the ventricle because in such a case the oblique opening of the ventricle will close during each contraction of the heart so that there will be minimum loss of blood. Similarly, haemorrhage will be minimum, if the weapon remains in situ with the blade occupying the space made by the penetration of the weapon.
In course of searching for the bullet or pellets or splinters of a bomb, difficulty may arise, particularly if these are lodged inside the lungs or the vertebral bones. Hence, it is very helpful if the dead body is subjected to X’ray examination before the starting of postmortem examination. An interesting feature notable with bullet or pellet injury of the ventricles of the heart is that life may be compatible for years, with these foreign substances there. In some cases, poisoning with the metal of the projectile (usually the lead) may occur, in case of long term stay of the projectile. In case of bullet injury to the chest wall, the splinter from a fractured rib may cause penetration in any direction.