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Objective: The purpose of this thesis was to determine the degree of difference between anthropometric and heel pad tissue characteristics of the lower extremities of PMHS compared to living populations as well as to establish a wholistic procedure for extensive measurements of the foot using methodology previously used in lower limb anthropometry, x-ray imaging, and ultrasound imaging studies.Methods: Thirty-seven PMHS were included in the anthropometry analysis, 21 PMHS were included in the x-ray analysis, and 32 PMHS were included in the ultrasound analysis. For the anthropometry, measurements were taken in seated and standing positions and included bimalleolar breadth, heel breadth, navicular height (medial prominence), navicular height (inferior medial border), talar head height, plantar curvature height, lateral malleolar height, medial malleolar height, acropodion foot length, hallux foot length, horizontal foot breadth, ball of foot length, and dorsum height. Comparisons were then made between left and right feet, seated and standing positions, males and females, and PMHS and living populations. For the x-ray analysis, two of the anthropometry measurements, navicular height (inferior medial border) and talar head height, had values for anthropometry compared against measurements determined through x-ray imaging. For the ultrasound analysis, ultrasound images were taken of the plantar foot at the calcaneus at loadings of 0, 5, 10, 15, 20, and 30 Newtons. Thicknesses, stiffnesses, and compressibility indexes were determined using the images, and these values were then compared against values seen in living populations. Results: Left and right feet were found to have no significant differences in anthropometry. Seated and standing positions were found to be significantly different in 12 of the 13 measurements. Male values were found to be significantly different from female values in both seated and standing positions for all measurements except for plantar curvature height. By determining percent difference values between seated and standing positions for both males and females, no significant difference was found between sexes in their respective measurement changes from seated to standing positions except in plantar curvature height and lateral malleolus height. Eleven of the 13 measurements showed agreement between PMHS and living populations, with talar head height and plantar curvature height showing greater than 10% difference. In the x-ray analysis, navicular height was significantly different between anthropometry and x-ray values, and talar height was not significantly different. In the ultrasound analysis PMHS were found to have thinner and stiffer heel pads with lower compressibility than living populations.Conclusions: A wholistic procedure for foot measurements and analysis was developed which incorporates methodology from previous literature. For foot measurement, x-ray imaging was shown to be necessary for certain landmarks but not for others. Results from this study have provided quantification of posture and sex differences as well as quantification for differences between PMHS and living populations for foot anthropometry. Differences were also quantified for the thickness, stiffness, and compressibility of PMHS compared to living populations. The results show that PMHS anthropometry sufficiently represents that of living people’s anthropometry when sex and postural differences are accounted for, but PMHS is not representative of living populations regarding heel pad thickness, stiffness, or compressibility, and these differences must be considered in lower extremity testing.

The sympathetic nervous system, a subdivision of the autonomic nervous system, innervates glands, smooth and cardiac muscle of the body and drives the “fight or flight” response. The objective of this study is to use anatomical and radiological methods to definitively identify and investigate the sympathetic chain, specifically ganglia from stellate through T5. The overarching goal of this research is to help guide clinical treatments, including nerve block and ligation procedures, for various disorders of the sympathetic nervous system, including cardiac arrhythmias, hyperhidrosis and pain syndromes. This study uses anatomical methods, including cadaveric dissection, optical tracking, anatomic relationships and landmarks, to investigate the characteristics of the sympathetic chain. This study also uses radiologic methods, including conventional radiography and 3 Tesla (T) magnetic resonance imaging (MRI) with a high-resolution 3D constructive interference in steady state (CISS) sequence, to provide a clinically applicable comparison to gross anatomic observations and measurements.

Decomposer organisms play a vital role in terrestrial nutrient cycling, breaking down complex organic compounds and providing nutrients for primary producers. Microbial communities and other decomposers associated with a vertebrate carcass, or the “necrobiome”, are critical for degradation and recycling of soft tissues following vertebrate mortality. The impact of microbial decomposers in vertebrate decomposition has been shown with regard to soil microbial communities, where the presence of soil microbes impact decomposition rate and undergo succession. However, current assessments of microbial ecology within decomposition-impacted soils have primarily focused on one aspect of microbial succession: succession of bacterial taxa for forensic applications. While this has provided a foundation of knowledge to build upon, it is still unclear how this succession is affected by extrinsic (e.g., environmental) and intrinsic (e.g., cadaver-related) factors and how microbial functions are impacted. These knowledge gaps are important for understanding how ecosystem processes are impacted by decomposition. The ultimate aim of this body of research was to improve our understanding of soil microbial succession during decomposition by assessing these knowledge gaps. Thus, this dissertation consisted of three research objectives: (1) evaluation of the effects of intrinsic factors on soil microbial succession, (2) evaluation of the effects of extrinsic factors on soil microbial succession, and (3) evaluation of soil microbial functional succession during decomposition. Two separate field studies were conducted. The first observed the early stages of decomposition of 19 subjects, while the second observed a longer term (one year) decomposition of three subjects. All subjects decomposed on the soil surface at the University of Tennessee Anthropology Research Facility. Overall, we show that soil microbial succession during decomposition is impacted by both intrinsic and extrinsic factors. This included body mass index, which affected soil chemical response and microbial succession, making it a factor of interest for future investigations. We also used metatranscriptomics to show that microbial gene expression shifted during decomposition and was still impacted following one year. Together, our investigation of factors that influence multiple aspects of microbial succession lays an important framework for understanding the ecology of human and vertebrate decomposition in terrestrial ecosystems.

Automotive crashes are a leading cause of death in the US, with side-impacts being the most fatal. Thoracic injuries are among the leading causes of such fatalities in small, elderly females. Thus, a series of six realistic side-impact post-mortem human surrogate (PMHS) sled tests were conducted. Results showed serious thoracic injuries in all PMHS, despite current side-impact anthropomorphic test devices (ATDs) predicting a The objectives of this study were to investigate the following in small, elderly female PMHS: 1) discrepancies between existing injury risk assessment tools and actual injury outcomes; 2) the effects of seatbelt pretensioners on thoracic injury; and 3) the effect of combined loading from the seatbelt pretensioner and side airbag on thoracic injury in side-impact.Prior to PMHS testing, SID-IIs ATD tests were run to match conditions to the previous study. A foam-padded pneumatic lateral impactor was used as a repeatable airbag surrogate. Three PMHS were tested, each under three different loading conditions: 1) A/P-only (seatbelt pretensioner), 2) lateral-only (airbag surrogate), and 3) combined loading (both). Anterior and posterior aspects of right and left ribs were instrumented with strain gages to detect potential fractures and fracture timing. Chest deflection was measured by axillary- and xiphoid process- level chestbands. Seatbelt load and spine motion were also measured. An anatomical dissection was completed after each test series to document all injuries.Each PMHS first underwent an A/P-only test, resulting in A/P chest compressions of 7-12% and no rib fractures. While the goal was to conduct one lateral-only and combined loading test per PMHS, number of tests and impact energy varied due to detected rib fractures or lack thereof. PMHS 1 only experienced one 4.9 m/s lateral-only impact due to 5 rib fractures occurring at 11% half-lateral compression. PMHS 2 underwent three lateral-only and two combined tests. Half-lateral compressions ranged from 4-8% for lateral-only and 7-8% for combined tests; 2 rib fractures occurred after the third lateral-only impact at 3.2 m/s. PMHS 3 underwent two lateral-only and one combined test. Half-lateral compressions measured 6-9% for the lateral-only and 7% for combined. PMHS 3 had 6 rib fractures in the second lateral-only impact at 3.0 m/s.Poor prediction of input impact energy from SID-IIs tests suggested low ATD biofidelity. A/P-only tests revealed that pretensioners alone do not likely cause rib fractures in fragile occupants. The high frequency of rib fractures in lateral-only tests restated the need for demographic-specific injury risk criteria. Strain gage data in combined tests showed initial tensile strain in the impact-side ribs that became compressive, indicating dynamic loading. Combined loading also reduced rib strain magnitude despite constant chest deflections. While these findings may imply an increased thoracic injury risk under combined loading, future work is needed to fully understand the underlying injury mechanism.

En este artículo estudiamos, desde una perspectiva iconográfica, política y antropológica, el motivo visual del cadáver y su presencia en la esfera pública en tiempos de pandemia. A partir del análisis de la representación del cuerpo muerto en las imágenes de los medios de comunicación actuales, hemos tratado de pensar cómo se transformaron los esquemas formales e iconográficos de presentación de la muerte con la irrupción, desde marzo de 2020, de la pandemia de Covid-19. El régimen pandémico, excepcional a nivel político y antropológico, supone un acercamiento particular a la problemática de la representación del cuerpo muerto (cuerpo anónimo, portador de un virus), cifrado en una dialéctica entre un régimen de omisión y censura y el desplazamiento de la representación de la muerte hacia la simetría acumulativa de las fosas o ataúdes vacíos que prefiguran el cadáver por venir. La iconografía pandémica, construida con frecuencia sobre el imaginario de la ciencia-ficción, perfila la inquietud deshumanizada de un futuro distópico. En esas condiciones de excepcionalidad, algunos cadáveres, a priori anónimos, se singularizan, mostrando, aún en el espacio en suspenso de la Covid-19, la permanencia de esquemas estructurales de violencia que se deben denunciar y combatir en presente. En ese sentido, proponemos también estudiar los cadáveres reivindicados por el Black Lives Matter y la peculiar forma representativa que toman, muy diferente a los de las víctimas de la epidemia. Finalmente, desde estas coordenadas y a partir del tratamiento mediático del cuerpo de Diego Armando Maradona, consideramos como significativo el retorno al centro de la esfera pública del cadáver icónico, que impone un régimen de extrema visibilidad y desborda los límites representativos de la excepcionalidad pandémica.

The effects of vertebrate decomposition are wide-ranging across multiple foodwebs, and have been shown to persist in the environment, however there is a lack of systematic assessment of these changes over long periods of time or in sufficiently high resolution as to resolve seasonal flux patterns. The ultimate aim of this body of research was to explore nematode systematics in decomposition environments, culminating in a pair of long-term human decomposition seasonal trials, in high resolution, with the specific intent of integrating the fields of soil chemistry, microbial ecology, and nematology in order to assess the relationships of cross-disciplinary impacts. Of these three fields, soil chemistry has the largest body of literature dedicated to its study. Microbial ecology, for forensic purposes, is still an emerging field, and primarily focuses on bacterial successional characteristics in the early phases of decomposition. Nematology as a forensic tool has had very little study dedicated to it, however initial results are promising. Therefore, prior to performing a fully integrated study, further examination of nematode community systematics was required in order to ascertain the nature of their responses to the decomposition environment. Our body of work consisted of three objectives: (1) evaluation of nematode communities in a multi-individual grave, (2) evaluation of longitudinal patterns in nematode diversity in an animal model system, and (3) evaluation of seasonal differences in decomposition patterns across the disciplines of soil chemistry, microbial ecology, and nematology, in high resolution and long-term. Overall, nematode communities were shown to exhibit persistent modification after four years in a grave, and successional patterns in a vertebrate surface-decomposition model system. The human seasonal study demonstrated that soil chemistry and fungal beta diversity were inextricably interlinked, as were nematode abundances and thermal effects, and that seasonal rates of change in decomposition progression are mirrored across all three disciplines. This suite of simultaneous changes is sufficiently compelling for us to recommend that it is absolutely crucial to broaden decomposition soil research into an interdisciplinary study in order to fully and accurately contextualize these processes in future work.

For nearly a century, heart disease has been the leading source of death and disease in the United States, causing the deaths of hundreds of thousands of individuals every year and burdening millions more with diminished health and severe disability. However, despite the significant known prevalence of heart disease, studies suggest that many more individuals—and particularly those within the female and elderly populations—may possess undiagnosed heart disease which remains undetected even after death due to the lack of autopsy examination. In the absence of autopsy, many cases of heart disease may never be identified, resulting in a skewed understanding of disease burden which may hinder improvements in diagnosis and treatment of heart disease. This may also impair accurate detection of high-risk individuals who are unknowingly susceptible to infectious diseases such as influenza, pneumonia, or—a more current concern—the recently discovered novel coronavirus-19. In addition, heart disease often carries strong genetic components, making it vital that undiagnosed heart disease be identified so that family members can likewise be made aware of their risk. In order to identify the prevalence of undocumented heart disease in the absence of autopsy examination, 50 cadaveric donor hearts were examined, and findings were compared with documented prevalence according to donor medical records. Results revealed that whereas only 30% possessed documented forms of heart disease, features consistent with mild to severe forms of heart disease were observed in 98% of donors. Since most of these donors were elderly, this suggests that the vast majority of the elderly population likely possesses mild to severe forms of heart disease. Undocumented heart disease was particularly prevalent in the female population, with 50% of female donors displaying undocumented features of heart disease in the absence of any documented form of CVD (heart disease or otherwise), although undocumented heart disease in the absence of documented CVD was also observed in 36% of male donors. Since cadaveric tissue has not previously been utilized for gene expression studies, an RNA extraction protocol was modified for embalmed tissue in order to identify genetic risk factors potentially associated with these undocumented cases of heart disease. This protocol yielded amplifiable RNA of sufficient yield and purity for microarray analysis. While the extent of RNA degradation varied between samples, microarray analysis revealed over 6,000 unique mRNA transcripts consistently detected in all cadaveric samples, including a wide variety of transcripts known to be associated with heart disease. This study is the first to identify the significant prevalence of undocumented heart disease in cadaveric donors and suggests that many forms of heart disease remain undiagnosed in the absence of autopsy, particularly in the elderly and female populations. This study is also the first to utilize embalmed cadaveric tissue for the purpose of gene expression studies. This technique will potentially provide unprecedented opportunities for genomic studies related to disease etiology within cadaver donors and allow for the identification of genetic risk factors which may have been passed on to family members. Collectively, these findings can be utilized to gain a more accurate understanding of heart disease burden within the population, potentially facilitating the identification of high-risk individuals and reducing the fatal effects of heart disease in those unaware of their risk.

During an under-body blast (UBB) event, an improvised explosive device (IED) delivers a high-energy blast beneath a military vehicle, exposing mounted Warfighters to considerable risk of severe lower extremity injuries. Loftis and Gillich (2014) determined that the lower leg and ankle region is the most common body region to sustain skeletal injury in military mounted combat events, comprising twenty-one percent of cases reported in the Joint Trauma Analysis and Prevention of Injuries in Combat (JTAPIC) database between 2010 and 2012. Injuries of the lower extremity are not always life-threatening. However, from a survivability standpoint, these injuries may affect the ability of the Warfighter to self-extricate and ambulate in the immediate aftermath of an UBB event. In addition, lower extremity injuries can lead to long term health complications and reduced quality of life (Dischinger et al., 2004). While some comparisons can be drawn from the study of civilian automotive crashes; the impact level, rate, location, and directions in UBB are fundamentally different for the lower extremity. Therefore, substantial research efforts to characterize and assess injuries unique to UBB are essential. The Warrior Injury Assessment Manikin (WIAMan), the Tech Demonstrator version of which was introduced by Pietsch et al. (2016), is the only anthropomorphic test device (ATD) designed to evaluate injury patterns in UBB conditions. However, there are no known injury assessment tools for the female Warfighter at this time. The overarching goal of this research effort is to determine the origin of potential differences in the response of females and males in UBB conditions. The results of this work contribute to the body of research concerning high-rate axial loading of the lower extremity and form the first detailed biomechanical account of UBB effects on female PMHS. This work will inform future decisions regarding the requirements for a valid injury assessment capability for female Warfighters in the UBB environment and the subsequent research needed to support those requirements. Ultimately, advancements can be made in modeling and simulation capabilities, injury assessment criteria, test methodologies, and design approaches for safer military ground vehicles and personal protective equipment (PPE). Improvements in these technologies will reduce morbidity and mortality rates among the U.S. Warfighter population, both male and female.

Post-mortem human surrogate (PMHS) head specimens were subjected to two different angular speed pulses. Each pulse was approximately a half-sine with either a peak angular speed of either 40 or 20 rad/s and duration of either 30 or 60 milliseconds. High-speed biplane x-ray was used to record the motion of the brain and skull via radio-opaque markers implanted at specified locations in the brain, and lead markers on the skull. Specimens were perfused to physiologic conditions throughout preparation and testing to maintain the integrity of the brain tissue and ensure coupling of the brain and skull. Intracranial pressure was measured anteriorly and posteriorly. The test event was controlled by a cam-follower-flywheel mechanism, which facilitated control of pulse parameters and provided a form of "infinite energy" so that the device and therefore the test input would not be influenced by the characteristics of the object under test. This approach kept the independent and dependent variables separated. The brain targets were also deployed in a prescribed manner with two methodologies that were scalable to different specimens. The repeatable input and target deployment schemes helped reduce experimental variation (between tests and subjects) to produce consistent response data. Displacement of the brain was calculated with respect to a body-fixed basis on the skull. The relative motion of the brain with respect to the skull was shown to be dependent on the location of the target in the brain. The major deformation axis of each target followed the contour of the skull or bony landmark to which it was closest. Intracranial pressure was relatively low because the changes were due to inertial effects in the absence of impact. Tests with lower speeds and longer durations produced less deformation, lower intracranial pressures, and longer pressure durations than the tests that were high-speed, short-duration. The response of the brain to rotation of the head was quantified at two test levels and on two PMHS specimens.

Motor vehicle crashes claim thousands of lives each year in the US, and injure millions more. The thorax is the region of the body at greatest risk for serious injury, and thus is of interest for increased protection. In order to improve systems providing occupant protection, a better understanding of the thorax is required, particularly for vulnerable occupants. The work of this dissertation is focused on increasing understanding of the thorax, and does so by examining instrumentation commonly used on the thorax, by introducing a novel analysis technique for understanding thoracic characteristics, and finally by presenting response and injury data for side impact loading.The first study presented here provides an answer to the question, “Do chestbands alter thoracic response to impact?” This was accomplished by conducting a series of repeated impacts on two post-mortem human surrogates (PMHS), at the same impact velocity with 0, 1, and 2 chestbands. This was done for various impact speeds for a total of 22 impacts on the two subjects. `Response’ was divided into global response, defined as chest deflection and thoracic stiffness, and local response, defined as the individual rib strain. Results showed no significant difference in global or local response, thus providing support for the commonly held assumption that chestbands do not alter thoracic response to impact.The second study introduces an analysis method, looking at rib strain as a function of chest deflection. An understanding of this relationship is intended to help bridge the gap between existing deflection-based injury criteria and strain-based injury prediction in finite element human body models. To this end, the strain-deflection (S-D) relationship was explored by rib level, fitting five different models to the data and constructing response corridors. It was additionally observed that the S-D relationship, or curve trajectory, tends to remain consistent across impacts on the same subject, even when those impacts are conducted at different velocities.The final study of this work begins an examination of thoracic response and injuries occurring in small, fragile, elderly females involved in side impact vehicle crashes. The testing methodology is described, which includes a door intrusion and lateral underbody motion applied to a subject who is placed on a mass-production driver seat equipped with a side airbag, belted (with pretensioner), and interacts with a mass-production door liner. Rib fractures were the most common injury observed, with the first fractures occurring anteriorly on the struck side, followed by fractures anteriorly on the non-struck side and fractures posteriorly on the struck side. Spinal acceleration values, chest deflections, airbag pressures, and seatbelt tensions are reported. While this study does provide a valuable understanding of the injuries in the employed impact mode, it is intended that future tests similar to these may be conducted and that the combined dataset may be used to produce response corridors and a thoracic injury criterion specific to small, fragile females.

Occupational formaldehyde exposure occurs during the embalming and preservation of cadavers as well as other work involving cadavers including moving, dissection, transportation, and cremation. This study examined formaldehyde exposure during the transportation of cadavers and dissected cadavers between medical universities in Ohio and during transportation between an Ohio and a Michigan medical university. Three events were sampled: one employee in one van during event one and two employees in separate vans during event two. Personal replicate samples were collected from the breathing zones of the workers during the cadaver transport. Transportation time included loading and unloading cadavers. A control vehicle was also sampled. Time-weighted average (TWA) exposure to formaldehyde ranged from 0.36 parts per million (ppm) (0.44 mg/m3) to 0.49 ppm (0.60 mg/m3). Eight-hour TWAs were below the Occupational Safety and Health Administration (OSHA) permissible exposure limit of 0.75 ppm (0.92 mg/m3). The eight-hour TWAs were below the OSHA action level of 0.5 ppm (0.62 mg/m3). All eight-hour TWAs exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) ceiling value of 0.3 ppm (0.37 mg/m3). The formaldehyde concentrations by transportation method demonstrated a statistically significant difference between exposures during the cadaver transport, dissected cadaver transport and the control.

Motor vehicle collisions (MVCs) are a leading cause of injuries and injury-related fatalities in the United States. The National Highway Traffic Safety Administration (NHTSA) reported over 21,250 vehicle occupant fatalities in 2011, with 1,240,000 injuries sustained by passenger car occupants alone. MVCs are a common cause of blunt abdominal injuries. It has been reported that approximately 9,000 front seat occupants sustain moderate to severe abdominal injuries in frontal MVCs in the United States each year. A detailed understanding of the occurrence and mechanisms of abdominal injuries, as well as knowledge of the biomechanical response and tolerance of the abdomen in crash-specific loading modes, could benefit the reduction of abdominal organ injury incidence in MVCs. Therefore, the objective of the research presented in this dissertation was to characterize abdominal injury mechanisms, tissue failure thresholds, and internal organ response to blunt impacts of the abdomen. Field accident data from the Crash Injury Research and Engineering Network (CIREN) database were analyzed to determine the occupant and crash characteristics associated with crash-induced hollow abdominal organ injuries. Dynamic equibiaxial tension tests were conducted on tissue samples obtained from the human post-mortem stomach, small intestine, and colon to characterize the material properties and failure tolerance of these tissues. The effects of cadaver orientation on the relative position of the abdominal organs of two cadavers were quantified, and high-speed biplane x-ray imaging was used to investigate the relative kinematics of the thoracic and abdominal organs of four cadavers in response to crash-specific loading modes. Test configurations included blunt abdominal and thoracic impacts and driver-shoulder seatbelt loading. The motivation for this research was to advance efforts toward abdominal organ injury mitigation in MVCs, with each aspect of this research generating novel injury biomechanics data with applications for future experimental testing and finite element modeling.

Kienbock's disease causes degeneration of the lunate bone in the wrist leading to pain and reduced function of the joint. Clinical studies have found a new technique, radial core decompression (RCD) to be clinically effective in improving early stage Kienbock's disease. However, there have been no biomechanical studies characterizing the changes in wrist kinematics following the RCD procedure. The purpose of this study is to determine the changes in lunate and scaphoid motions following the RCD procedure.This study employs an electromagnetic 3-dimensional tracking system, Polhemus 3-SPACE, to measure the motions of the lunate, scaphoid, and third metacarpal in four cadaveric specimens. Specimens were partially dissected and sutures were attached to five major tendons used for wrist motion. Motion sensors were installed on the lunate,scaphoid, and third metacarpal, and a source was installed on the radius. CT scans were taken of the specimens and digitally reconstructed to determine the relationships between bony coordinate systems and sensor coordinate systems. Wrist specimens were installed in a custom test rig and weights were attached to the sutured tendons to simulate muscle tone. The wrists were passively moved through Flexion/Extension and Radial/Ulnar Deviation motion cycles with motion data collected at various positions through the cycles.After collecting motion data for intact wrist specimens, RCD procedures were performed and motion data was collected for the post-RCD wrists. Joint Coordinate Systems were developed for each specimen and test results were calculated as flexion, ulnar deviation, and pronation angles for each position of Flexion/Extension and Radial/Ulnar Deviation motion. Results were normalized so that statistical comparisons could be performed.Results shows statistically signicant differences in wrist motion following the RCD technique. However, most of these differences were less than 4 degrees. This suggests there are minimal clinically-relevant changes in wrist kinematics following the RCD technique.

Head and spine injuries, such as traumatic brain injury, skull fracture,concussion and osteoligamentous cervical spine injury continue to beprevalent in motor vehicle crashes, athletics and the military. Automotivesafety systems, athletic safety equipment and military personal protectiveparaphernalia designs have generally focused on protection discretelydesigned on a component basis – head or spine – but not a systems basis,considering the head-spine linkage simultaneously. But since the cervicalspine acts as the attachment point for the head, the boundary conditionsapplied to the cervical spine influence the behavior of the head. Hence, inanalyzing injury risk for the head and the spine, each structure composesone portion of an intrinsically linked osteoligamentous system; thus injuryrisk for the head and the cervical spine might be more appropriatelyconsidered concurrently as opposed to individually.Historically, component-based injury protection designs have utilizedhead and cervical spine injury risk criteria developed from human, animaland anthropomorphic surrogate studies. While a plethora of these priorstudies separately analyzed head injury risk via linear acceleration, HeadInjury Criterion (HIC) or Gadd Severity Index (GSI), or cervical spine injury risk via axial/shear forces, bending moments or the Neck Injury Criterion(Nij), relatively few of these studies employed a systems-based approach tounderstand coupled head-cervical spine injury risk behavior.Thus, designing for optimal head and cervical spine injury protectionmay not be as trivial as separate consideration of head or spine componentinjury thresholds. Therefore, through a series of six biomechanicalengineering studies that comprised the chapters of this dissertation, the workpresented here broadly investigated head and cervical spine injury protectionon a systems-based approach considering head and cervical spine injury risksimultaneously. In Chapter 1, injury risk in inertial loading during real-worldlow energy minor rear car crashes was analyzed. In Chapter 2, these minorcrashes from Chapter 1 were further investigated via use of numericalsimulation in MADYMO. While Chapters 1 and 2 explored low energy carcrash loading, Chapter 3 explored multivariate head and cervical spine injuryimplications from direct head loading during frontal airbag inflation in highenergy experimental car crashes. Chapter 4 expanded the direct frontalhead impact loading analyzed in Chapter 3 to include oblique and lateralimpact loading during impact experiments with a Hybrid III anthropomorphictest device. The low- and high-energy injury analysis methods developed inChapters 1 through 4 helped drive the study of multivariate injury risk inresponse to experimental omnidirectional athletic head impacts in Chapter 5.Chapter 6 further built on the high-energy athletic impacts from Chapter 5via Matlab and Simulink simulation of helmeted impacts using a systemsdynamics approach. Finally, Chapter 7 analyzed development of an impact pendulum, pilot cadaveric injury response to direct head impact and analysisof similar impacts in a helmeted human surrogate. The results of all of theserelated studies indicated that head and cervical spine injury risk wereinterrelated during direct or inertial car crash and athletic impacts.

Mass properties of the human head are critical elements in developing neck injury threshold criteria in acceleration and impact environments. In order to accurately simulate the dynamics of the head in impact and acceleration environments, valid mass properties data for the human head must exist. The purpose of this study was two-fold: First, to directly measure and generate a useful data set of human head mass properties and anthropometry, and second, compare the results from the direct measurement to measurements obtained using computed tomographic (CT) analyses of the human head. Four cadaveric human heads, all male, were measured. For the direct measurement procedure, each frozen specimen was secured in a lightweight-aluminum box. The mass, center of gravity (CG) and principal moments of inertia (MOI) were then measured. These same properties of the box alone were subtracted from the measured quantities to determine each specimen's mass properties. For the CT analysis, the identical specimen preparation was imaged with CT. With both slice collimation and table feed set at 1 mm, the CT image resolution was 0.284 mm3/voxel. Segmentation of tissue types based on density thresholds was used to divide the volumetric data into brain matter, bone, and fat/skin. Surfaces from these groups were extracted to create volumes representing these structures. Assigning mass densities to the segmented volumes, the mass properties of the head were calculated using MIMICS, a 3D ing program and results were compared.The final results showed the method to be accurate. The average weight for the directly measured heads was 8.96 lb compared to 8.99 lb for the calculated. The average shift in the z-axis (CGz) for the directly measured heads was 0.91 in above the Frankfort origin while the measured shift was 1.00 in on average. Overall, there was no significant difference seen among any of the parameters at α = 0.05.

It has been shown in side impact automobile accidents that the shoulder is the point of first contact with the intruding door, causing large forces to be carried by the shoulder complex and, upon failure, into the thorax of the occupant. Shoulder kinematics and the distribution of load through the shoulder girdle are well documented for every day functions; however, the response of the shoulder to impact and the transmission of load to the thorax under high-energy impact are not well understood. The mechanical response, or stiffness properties, of the shoulder that would be helpful in future dummy development is also not known. The shoulder response under the oblique loading that occurs when the intruding door does not strike in a purely lateral manner is unknown. The response of the shoulder to impact and the protective relationship between the shoulder girdle and the thorax is critical to understanding human response to lateral impact and to developing countermeasures to prevent and mitigate thoracic, as well as shoulder, trauma. The purpose of this study was to define injury criteria for the shoulder, define the stiffness of the shoulder in response to both lateral and oblique loading, and investigate the protective relationship between the shoulder girdle and the thorax. This study was conducted in two separate phases. Phase I of the research was comprised of 24 lateral shoulder impacts. Phase II included 14 lateral and oblique shoulder impacts. Of the 14 tests, four of them were conducted lateral to the shoulder along the subject’s y-axis, four of them were conducted 15° anterior to this axis, and six were conducted 30° anterior to the subject’s y-axis. All of the testing utilized a pneumatic ram to impact the shoulders of post-mortem human subjects (PMHSs) at the level of the glenohumeral joint. The first thoracic vertebrae and both shoulders of the subject were instrumented with tri-axial linear accelerometers on the sternum, clavicle, acromion process, and inferior angle of the scapula. The impacting mass was instrumented with an accelerometer and displacement transducer. In addition to this instrumentation, the tests were documented by high-speed digital imagery. Radiographs (x-rays), magnetic resonance images (MRIs), and autopsies were used to document injury to the subjects. The results from the two phases of testing revealed differences between the stiffness of the shoulder when loaded laterally to that when it is loaded obliquely. The shoulder was found to deflect more medially when loaded obliquely then when it is loaded laterally. This can be attributed to the ability of the scapula to slide posteriorly around the thoracic cage. The ability of the shoulder to displace medially while simultaneously deflecting posteriorly in oblique impact is important to replicate in the ATDs because it results in the load being transmitted to the upper thoracic cage.