Human Anatomy and Diseases III: Respiratory, Lymphatic, Digestive, Urinary, and Reproductive Systems
Qizhi Chen, George Thouas in Biomaterials, 2015
Although respiration is often considered the same as breathing, the latter is actually just part of the former. Externally, breathing is the mechanical process that moves air into and out of the lungs, via either costal (thoracic) and diaphragmatic (abdominal) motion of the chest cavity, which the lungs are held into via a slight vacuum pressure. In costal breathing, the major structure causing the movement of the air is the rib cage, which expands and contracts the lungs within, by flexible joints at both the spinal column and the sternum (chest). In diaphragmatic breathing, the sheet-like muscle of the diaphragm at the bottom of the chest cavity depresses like a membrane pump, pulling the lungs down and thereby filling them with air. Both forms of breathing usually work in unison, although diaphragmatic breathing is more efficient in filling the lungs.
Biomechanics of the Spine
Manoj Ramachandran, Tom Nunn in Basic Orthopaedic Sciences, 2018
Interest in biomechanics of the spine developed in the latter half of the twentieth century. Sir Frank Holdsworth proposed the two-column model of the spine in 1963. The functional spinal unit is the smallest physiological unit of the spine that exhibits biomechanical properties similar to that of the entire spine. White and Panjabi defined spinal stability as the ability of the spine under physiological loads to limit patterns of displacement that can damage or irritate the spinal cord or nerve roots and, in addition, to prevent incapacitating deformity or pain caused by structural changes. A complete free-body diagram of the lumbar spine should include the individual weights of the head, trunk, upper limb and the weight lifted, along with their respective distances from the centre of spinal motion. The thoracic spine is unique in being the least mobile segment of the spine and having additional stability and stiffness as a result of its articulation with the rib cage.
Skeletal disorders and neuromuscular disease
Pallav L Shah, Felix JF Herth, YC Gary Lee, Gerard J Criner in Essentials of Clinical Pulmonology, 2018
Skeletal disorders affecting the spine and rib cage fall broadly into the categories of scoliosis, kyphosis, lordosis, and pectus abnormalities. The degree of lateral curvature in scoliosis is expressed by the Cobb angle, which is calculated from a standing coronal radiograph as shown in Figure 53.1. Kyphosis indicates backward and lordosis forward curvature in an anteroposterior (median) plane. In fact, most idiopathic thoracic scolioses incorporate a lordotic and rotatory element. Pectus abnormalities include pectus excavatum (sunken chest) and pectus carinatum (pigeon chest). A classification of skeletal conditions is shown in Table 53.1.
3D reconstruction of rib cage geometry from biplanar radiographs using a statistical parametric model approach
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2016
B. Aubert, C. Vergari, B. Ilharreborde, A. Courvoisier, W. Skalli
Rib cage 3D reconstruction is an important prerequisite for thoracic spine modelling, particularly for studies of the deformed thorax in adolescent idiopathic scoliosis. This study proposes a new method for rib cage 3D reconstruction from biplanar radiographs, using a statistical parametric model approach. Simplified parametric models were defined at the hierarchical levels of rib cage surface, rib midline and rib surface, and applied on a database of 86 trunks. The resulting parameter database served to train statistical models which were used to quickly provide a first estimate of the reconstruction from identifications on both radiographs. This solution was then refined by manual adjustments in order to improve the matching between model and image. Accuracy was assessed by comparison with 29 rib cages from CT scans in terms of geometrical parameter differences and in terms of line-to-line error distance between the rib midlines. Intra and inter-observer reproducibility was determined for 20 scoliotic patients. The first estimate (mean reconstruction time of 2 min 30 s) was sufficient to extract the main rib cage global parameters with a 95% confidence interval lower than 7%, 8%, 2% and 4° for rib cage volume, antero-posterior and lateral maximal diameters and maximal rib hump, respectively. The mean error distance was 5.4 mm (max 35 mm) down to 3.6 mm (max 24 mm) after the manual adjustment step (3 min 30 s). The proposed method will improve developments of rib cage finite element modelling and evaluation of clinical outcomes.
Computational model of rib movement and its application in studying the effects of age-related thoracic cage calcification on respiratory system
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2010
A. Vaziri, H. Nayeb-Hashemi, B. Akhavan-Tafti
A 3D finite element model of rib cage movement is developed and used to study the role of age-related costal cartilage and sternocostal joint calcification, as well as respiratory muscle weakness on the ‘bucket-handle’ movement of human rib. The volume displacement of the rib cage is related to changes in its circumference using an empirical equation presented by Agostoni et al. (1965, J Appl Physiol, 20:1179–1186). A systematic study is carried out to quantify the role of costal cartilage, sternocostal joint calcification and muscle weakness on the volume displacement of the rib cage. The results provide insight into some of the mechanisms underlying age-related changes in the respiratory system.
Age-Dependent Factors Affecting Thoracic Response: A Finite Element Study Focused on Japanese Elderly Occupants
Published in Traffic Injury Prevention, 2015
Jacobo Antona-Makoshi, Yoshihiro Yamamoto, Ryosuke Kato, Fusako Sato, Susumu Ejima, Yasuhiro Dokko, Tsuyoshi Yasuki
Objectives: The ultimate goal of this research is to reduce thoracic injuries due to traffic crashes, especially in the elderly. The specific objective is to develop and validate a full-body finite element model under 2 distinct settings that account for factors relevant for thoracic fragility of elderly: one setting representative of an average size male and one representative of an average size Japanese elderly male. Methods: A new thorax finite element model was developed from medical images of a 71-year-old average Japanese male elderly size (161cm, 60 kg) postmortem human subject (PMHS). The model was validated at component and assembled levels against original series of published test data obtained from the same elderly specimen. The model was completed with extremities and head of a model previously developed. The rib cage and the thoracic flesh materials were assigned age-dependent properties and the model geometry was scaled up to simulate a 50th percentile male. Thereafter, the model was validated against existing biomechanical data for younger and elderly subjects, including hub-to-thorax impacts and frontal impact sled PMHS test data. Finally, a parametric study was conducted with the new models to understand the effect of size and aging factors on thoracic response and risk of rib fractures. Results: The model behaved in agreement with tabletop test experiments in intact, denuded, and eviscerated tissue conditions. In frontal impact sled conditions, the model showed good 3-dimensional head and spine kinematics, as well as rib cage multipoint deflections. When properties representative of an aging person were simulated, both the rib cage deformation and the predicted number of rib fractures increased. The effects of age factors such as rib cortical thickness, mechanical properties, and failure thresholds on the model responses were consistent with the literature. Aged and thereby softened flesh reduced load transfer between ribs; the coupling of the rib cage was reduced. Aged costal cartilage increased the severity of the diagonal belt loading sustained by the lower loaded rib cage. Conclusions: When age-specific parameters were implemented in a finite element (FE) model of the thorax, the rib cage kinematics and thorax injury risk increased. When the effect of size was isolated, 2 factors, in addition to rib material properties, were found to be important: flesh and costal cartilage properties. These 2 were identified to affect rib cage deformation mechanisms and may potentially increase the risk of rib fractures.