270 MEDICAL JURISPRUDENCE ncial wound, 1.2 cm. X 1-1 cm. in tlie anterior wall of the oesophagus. The bone was directed obliquely downwards, backwards and outwards. Its lower end had made an irregularly circular opening, 1.1 cm. in diameter, in the postero-lateral wall and another opening, 1 cm. in diameter, in the descending aorta about J-" below the bend. In vehicular accidents the aorta may be ruptured by intense compres- sion of the chest without any signs of external injury to the chest wall and without fracture of the ribs. Cleland33 reports a case in which a young airman, while walking with a companion with his back to the oncoming traffic, was struck from behind by a taxi cab, dragged a short way and then thrown to the road. At the post-mortem examination there was no external injury to the chest and the ribs were not fractured, but the aorta and pulmo- nary artery were torn across, as though cut by a knife. There was also a large tear through the base of the heart and left auricle with rupture of the pericardium behind the heart. Just above the point of severance in the aorta there was another partial tear. Spontaneous rupture may occur from local diseases of the aorta, or even when there is little or no change in the aorta, especially in those cases where the aorta has only two valves or there is stenosis of the aortic isthmus. A case 34 is recorded of a healthy man, aged 48 years, in whom two large ruptures were found in the aortic arch with a dissecting aneurism and profuse haemorrhage in the left pleural cavity. The whole of the aortic arch showed areas of necrosis, which were most marked at the site of the rupture. The ruptures had occurred with an interval of a month in each: the last which proved fatal took place when the patient was asleep in bed. There was a history of high blood pressure for a year, but there was no evidence of syphilis or other inflammations. Diaphragm.—Wounds of the diaphragm are liable to be produced by penetrating wounds of the chest or of the abdomen. They are not rapidly fatal unless the important organs in contact with it are also wounded. In non-fatal cases diaphragmatic hernia may subsequently occur after the wound has healed and a cicatrix has formed. Rupture of the diaphragm may be caused by a severe blow or a fall from a height, from compression of the trunk under a wheel of a heavy bullock cart, motor car or railway carriage or from a sudden increase in the abdo- minal pressure. Rupture usually occurs near the central tendon on the left side, and is often accompanied by visceral injuries or displacements. It gives rise to much pain on coughing or deep breathing, and may cause death from severe shock. ABDOMEN The Abdominal Parietes.—Injuries of the abdominal parietes may be contusions, abrasions, and non-penetrating or penetrating wounds. Contusions of the abdominal parietes are produced by a blunt weapon, a kick, a carriage wheel passing over the abdomen, or by a fall. It is not necessary that they "should show any external mark of injury on the skin. Sometimes, an effusion of blood may be seen in the tissues or muscles under the spot where violence was used; but it must be borne in mind that an effusion of blood in the muscles may occur spontaneously as a result of disease without any external violence. Abrasions on the abdominal parietes are generally caused by vehicular accidents or by falls from a height. Contusions and abrasions of the abdominal parietes are, as a rule, simple, unless accompanied by lesions of the visceral organs, when they prove fatal from shock, haemorrhage, or from peritonitis. In some cases, peritonitis may occur without evident injury to any of the abdominal organs. Besides, it has already been mentioned that a blow on the epigastric region (pit of the stomach) may cause death by its inhibitory action on the heart 33. Ked. Jour. Ausforl, Sep. 9, 1944, Vol. 31, p. 278. 34. Brit. Med. Jour., Aug. 13, 1932, Ep., p. 29.