Thesis (Ph.D.) -- University of Adelaide, Dept of Anatomical Sciences, 2003? / Bibliography: l. 280-333.

Spinal loading is often measured by a change in stature or height. Changes in height are largely due to creep in the spinal tissues, especially in the intervertebral discs. Short-term loading results in an immediate relatively large loss of height which is quickly recovered when the load is removed. Sustainable loading causes the same quick loss followed by a prolonged, slow loss of height which will eventually attain a plateau. Daily activities involve a variety of loading conditions with the trunk in various postures. In general, daily activities involve sustained loading in the upright position. / Thesis (PhDPhysiotherapy)--University of South Australia, 2006.

Thesis--M.D., University of Hong Kong, 1985.

Thesis, M.D., University of Hong Kong, 1985. / Also available in print.

archives@tulane.edu / As the average life expectancy continues to increase globally, the scientific community must meet the parallel challenge of extending the healthy life expectancy of the ever-growing aged population. Aging-related decline in motor control is a crucial aspect of this challenge because it diminishes independence and hinders daily living abilities, leading to greater disability burden on the remaining population. While peripheral nervous and motor systems are certainly involved in this impairment, attention to those structures has come at the expense of more complete understanding of motor control by the aged central nervous system. This dissertation expands our knowledge of this area with a specific focus on the cortex. First, this has been achieved by identifying differences in steady-state structural plasticity in the primary motor cortex (M1) of young and aged mice using chronic in vivo imaging of dendritic spines, the sites of excitatory input to pyramidal neurons that process the bulk of outgoing information from this brain area. These results indicate that at baseline conditions the dendritic spines of the aged M1 are subject to increased turnover, including formation and stabilization, while enduring decreased rates of long-term survival. Secondly, ensuing work combined in vivo imaging with motor skill training and revealed that, while unsuccessful at causing learning-induced structural plasticity of dendritic spines, motor training results in a muted learning-induced structural plasticity response by the en passant boutons (EPBs) of L2/3 parvalbumin-expressing interneurons in the aged M1. These experiments also uncovered a baseline decrease in EPB density and increase in EPB size on the aged axon. Lastly, mesoscale, awake imaging equipment was designed and built to enable future study of brain-wide engagement of various cortical areas during motor learning and performance. The product of this dissertation is a greater understanding of the impact of normal aging on the M1 at the cellular and synaptic level outside of and during motor skill practice, and it also provides an avenue for further study of larger scale changes in cortical connectivity with aging. / 1 / Andrew Davidson

Bibliography: l. 280-333. This study investigates the osteometry and variation of the human spine. 348 human skeletons dating from 28,000 B.C. to the mid-20th century A.D. from 24 sites mainly in Switzerland and Southern Germany, and without macroscopic pathology, were measured with a caliper. The samples showed a microevolutionary increase in most of the spinal variables. As both mean values and standard deviations increased, this higher intra-group variability could be explained to be a result of relaxed natural selection. Various environmental or genetic factors could explain the short-term alteration of the spinal osteometry. The relative smaller size and decrease with age of the bony outline of the neural pathways in males could explain their high vulnerability to modern lower back pathologies.

Cervical spinal fusion cages are primarily used to stabilize intervertebral space and promote fusion between two vertebrae. Current cervical cages are made of either titanium or polyetheretherketone (PEEK), with PEEK recently becoming the more favorable choice due to its MRI compatibility. While previous research reveals ranges of pore diameters ideal for bone ingrowth, the effect of pore size, porosity, layer thickness and strut thickness on mechanical properties such as shear strength for PEEK, are not known at this time. The goal of this study was to determine the effect of pore size and other parameters on shear strength of surface porous PEEK. Micro-computed tomography (μCT) was used to analyze the porous layers on PEEK and the samples will then undergo shear testing. The data obtained was used to look at trends in parameters and their effect on shear strength in hopes of ultimately optimizing those parameters to promote osseointegration, while maintaining the ability to withstand shear stresses the device will face while implanted in the cervical spinal region of the body.

The aim of the study was to examine the growth and the shape of the lumbar vertebral canal throughout life. A unique collection in the Natural History Museum, London provided many infant spines along with adult ones in perfect condition. Unmagnified silhouette photographs were taken of the vertebrae and the size of the canals was measured by a computer. It was found that in midsagittal diameter and cross-sectional area the vertebral canal was fully matured by 1 year of age at L1-L4 and by 6 at L5. The midsagittal dimension was larger in many infant spines that in the adult. The interpedicular diameter grew at L1 until 10 years of age, at L2-L5 until adulthood while the perimeter did not change at the cranial 3 vertebrae, however, grew at the caudal levels until 16 years of age. The shape of the vertebral canal showed changes at the cranial four levels until adulthood as regards the trefoil configuration, the circularity and the situation of the centroid. At L5 circularity increased throughout life showing degenerative changes by increasing age. Trefoil configuration appeared in adulthood at L5 and its degree as well as its incidence did not change throughout life and generally was not associated with degenerative changes. In the second study anthropometric measurements of head circumference, clavicle length and lower limb lengths were compared to vertebral canal size taken from CT scans. The midsagittal diameter of the canal did not correlate with the other bone measurements, however, the interpedicular diameter showed a relationship. This dimension has significant growth potential like the clavicles and the long bones and to a less extent the skull. This also shows that the neural contents probably exert an effect on the growth of the canal. In the third study MRI measurements of adult lumbar canals were compared to the obstetric data of the subjects to investigate whether on adverse ante-natal environment can cause a disturbance in canal growth, thus, a small canal.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 71-86). Also available via the Internet.

Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 109-117).