264 MEDICAL JURISPRUDENCE CHEST Injuries of the chest are mostly accidental, occasionally homicidal, and rarely suicidal. Traumatic Asphyxia.—This results from severe compression of the chest and abdomen sufficient to prevent respiration for an appreciable length of time, as when an individual is crushed in a dense crowd or under a heavy object, or caught between the two buffers of a railway carriage. In such cases the face and neck are deeply cyanosed, accompanied by ecchymoses of the skin and conjunctivse. This discoloration is brought about by mechanical overdistension of the smaller veins and capillaries with stasis of deoxygenated blood. It extends to the root of the neck, and rarely passes down beyond the level of the clavicles owing to the absence of com- petent valves in the jugular and facial veins. The discoloration may disappear in ten to fourteen days without passing through the colour changes of a bruise, if it is not associated with severe injuries. Coullie 12 describes the case of an epileptic young man, who suffered from traumatic asphyxia caused by the unyielding collar-band of his shirt compressing the jugular veins, together with the partial asphyxia, high blood pressure, and fixation of the chest caused by the epileptic fit. Wall.—Contusions and abrasions of the chest wall may be caused by a blunt weapon, fall or crush under a heavy weight as in vehicular accidents. These may be accompanied by fractures of the ribs or sternum, or associated with grave visceral injury. Even when not accompanied by such injuries severe blows on the chest wall may produce concussion of the chest causing considerable shock followed by death. Simple contusions and abrasions of the chest wall may be followed by pleurisy or pneumonia. Wounds of the chest wall are not dangerous, unless the cavity is pene- trated and a vital organ is injured. In non-penetrating wounds there may be free haemorrhage from the divided mammary and thoracic arteries. Ribs.—Fracture of the ribs results from direct violence, as by blows or stabs, and from indirect violence as in compression of the chest or very rarely from muscular contraction during violent coughing, sneezing, or straining. When due to direct violence it is more dangerous, as the splinters are driven inwards and are likely to injure the underlying pleura, lungs, heart, large vessels, liver, or diaphragm, while in indirect violence fracture occurs at the most convex parts of the ribs near their angles, and the frag- ments are driven outwards. The ribs that are most frequently fractured are the middle ones, viz. the fourth, fifth, sixth, seventh and eighth, as they are most prominent and fixed at both ends. The upper ribs are not usually fractured unless very great force is used, when the lesions of the viscerar as a rule, occur. The lower ribs often escape on account of their great mobi- lity. Owing to diminished elasticity and increased brittleness of bones in old age, rickets, osteo-malacia, general paralysis of the insane and general wasting diseases, fracture of the ribs is liable to occur easily from the slightest violence. Symmetrical^fractures of the ribs on both sides are often met with, when a person sits on the chest and compresses it considerably by means of the knees or elbows, by trampling under feet, or by means of two bamboos, a -process known as "bans dola. They may also occur in accidents as in a fall from a height, or when run over by a heavy bullock cart or motor car or when caught between railway buffers. In such cases the ribs are often fractured in front near the costal cartilages, where the compress- 12. Brit. Med. Jbwr, Sep. 29, 1928, p. 569.