Mechanism of transverse fracture of the skull base caused by blunt force to the mandible.

Transverse fracture of the skull base is common both in the crushing of temporal regions of the skull and in the case of force acting on one temporal region. However, the mechanism of transverse skull base fracture caused by maxillofacial force has not been fully clarified. To provide an injury identification basis for forensic pathologists and clinicians, this paper combines accident reconstruction and finite element analysis methods to study the injury mechanism of an incomplete transverse fracture of skull base after the injured individual's mandible was subjected to violence in a traffic accident. The results show that after the injured individual's mandible was subjected to violence, forces in the direction of the left mandibular fossa and the right mandibular fossa were generated, creating the component forces. The combination of the two forces can produce a crushing effect toward the center of the skull base, as if the left and right temporal regions are being crushed, and the stress is concentrated at the joint of the mandible, the middle cranial fossa and the hypophyseal fossa. When the stress exceeds a certain limit, it will cause a transverse fracture of the skull base.

[Morphological analysis of cardiac rupture due to blunt injury, cardiopulmonary resuscitation and myocardial infarction in forensic pathology].

OBJECTIVE: To analyze the morphological features and forensic pathological characteristics of cardiac ruptures of different causes for their differential diagnosis. METHODS: We analyzed the data of 44 autopsy cases of cardiac rupture from 2014 to 2017 in our institute, including 11 cases caused by blunt violence with intact pericardium, 4 caused by cardiopulmonary resuscitation (CPR), 9 by myocardial infarction, and 20 by aorta dissection rupture.The gross features and histopathological characteristics of cardiac rupture and pericardial effusion were analyzed and compared. RESULTS: Cardiac ruptures caused by blunt violence varied in both morphology and locations, and multiple ruptures could be found, often accompanied with rib or sternum fractures; the volume of pericardial effusion was variable in a wide range; microscopically, hemorrhage and contraction band necrosis could be observed in the cardiac tissue surrounding the rupture.Cardiac ruptures caused by CPR occurred typically near the apex of the right ventricular anterior wall, and the laceration was often parallel to the interventricular septum with frequent rib and sternum fractures; the volume of pericardial blood was small without blood clots; microscopic examination only revealed a few hemorrhages around the ruptured cardiac muscular fibers.Cardiac ruptures due to myocardial infarction caused massive pericardial blood with blood clots, and the blood volume was significantly greater than that found in cases of CPR-induced cardiac rupture (P < 0.05);lacerations were confined in the left ventricular anterior wall, and the microscopic findings included myocardial necrosis, inflammatory cell infiltration, and mural thrombus.Cardiac tamponade resulting from aorta dissection rupture was featured by massive pericardial blood with blood clots, and the blood volume was much greater than that in cases of cardiac ruptures caused by blunt violence, myocardial infarction and CPR (P < 0.05). CONCLUSIONS: Hemorrhage, inflammatory cell infiltration, and lateral thrombi around the cardiac rupture, along with pericardial blood clots, are all evidences of antemortem injuries.