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Comparative analysis of the effect of nonlinearities on the lumbar segment stress/strain of the spine after correction of spondylolisthesis
Holá, Lucia ; Ščerba, Bořek (referee) ; Vosynek, Petr (advisor)
This final thesis focuses on the stress-strain analysis of the physiological, postoperative and degenerative state of the lumbar spine segment. The aim of this thesis is to implement nonlinear material characteristics into previously made computational models and to compare these two models. The solution is performed by computational modeling using the finite element method. The geometry model was made by modification of the previous model of geometry. The group of degenerative state models comprises of three different levels of spondylolisthesis, according to Myereding’s classification. Based on the performed analysis, it was found that the increasing severity of spondylolisthesis, as well as the change in material definition plays a huge role in the stress development in the intervertebral discs and in the vertebrae. The total deformation of the spine segment increases with the use of nonlinear material characteristics, as well as with the increasing variability from the physiological state. However, the stress distribution in the intervertebral disc decreases with the use of nonlinear material characteristics and in case of the vertebral stress distribution increases, unlike in the linear material models. The biggest similarity with the physiological state of the lumbar spine segment was found in the postoperative state using the spinal implants.
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His bundle in phylogenesis, ontogenesis and pathology
Tremerová, Aneta ; Gregorovičová, Martina (advisor) ; Kolář, David (referee)
His bundle is a part of the cardiac conduction system of mammals, birds and crocodilians. His bundle is important for high cardiac output in endothermic vertebrates. His bundle is a connection between atria and ventricles in fibrous atrioventricular isolation and it serves as an electrical conduction pathway via bundle branches to ventricular apex, where ventricular contraction begins. Defect in cardiac conduction system leads to cardiac arrhytmia and can cause sudden cardiac death. Thesis describes development of His bundle in mammals and birds, its phylogenensis and atrioventricular conduction in other vertebrates. Thesis also describes disorders of atrioventricular canal development, fibrous anulus and His bundle such a preexcitation syndromes and congenital heart block. Thesis also depicts history of a discovery of the atrioventricular conduction tissue. Key words: cardiac conduction system, His bundle, atrioventricular canal, anulus fibrosus, ventricular preexcitation, perinatal AVRT, WPW syndrome, congenital heart block
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