Academic literature on the topic 'Thoracic vertebrae – Physiology'

Aim. To reveal the patterns of the changes of osteometric characteristics of the adults living in the Ural region. Methods. 56 cadavers of human beings at the age of maturity were analyzed (28 women aged 21 to 55 years, and 28 men aged 22 to 60 years) being the residents of the Ural region. The scheme recommended by the Symposium on Age Periodization at the Institute of Age Physiology in 1969, was used for distribution by age groups. Osteometry and statistical method were used. Results. In the cervical spine, the greatest sagittal size was determined in the spinal process of the VII cervical vertebra (30.9±1.79 mm), in the thoracic spine — in the VII thoracic vertebra (41.5±2.4 mm), and in lumbar spine — in the III lumbar vertebra (36.4±0.95 mm). The frontal size of vertebral bodies increased from overlying vertebrae to underlying ones, however, the decrease in the frontal size of vertebral bodies was noted from the I thoracic to the VI thoracic vertebra, and starting from the VII thoracic vertebra its further increase was observed. The sagittal size of vertebral body increased only from the II cervical vertebra to the III lumbar one. The sagittal size of the bodies of the III–V vertebrae was within the range of 32–34 mm. The sizes of vertebral arch pedicle allow conducting the transpedicular fixation at the level of all vertebrae, but it should be taken into account that in V and VI thoracic vertebrae frontal size of arch pedicle is the least as compared to other levels. The frontal sizes of spinal canal were more than sagittal ones at the levels of all vertebrae, with the exception of atlas and the V thoracic vertebra. Conclusion. The results can serve as the basis for performing any surgical interventions on the spine and as the norm for evaluation of its pathological changes.

The vertebrae of sauropod dinosaurs are characterized by complex architecture involving laminae, fossae, and internal chambers of various shapes and sizes. These structures are interpreted as osteological correlates of a system of air sacs and pneumatic diverticula similar to that of birds. In extant birds, diverticula of the cervical air sacs pneumatize the cervical and anterior thoracic vertebrae. Diverticula of the abdominal air sacs pneumatize the posterior thoracic vertebrae and synsacrum later in ontogeny. This ontogenetic sequence in birds parallels the evolution of vertebral pneumaticity in sauropods. In basal sauropods, only the presacral vertebrae were pneumatized, presumably by diverticula of cervical air sacs similar to those of birds. The sacrum was also pneumatized in most neosauropods, and pneumatization of the proximal caudal vertebrae was achieved independently in Diplodocidae and Titanosauria. Pneumatization of the sacral and caudal vertebrae in neosauropods may indicate the presence of abdominal air sacs. Air sacs and skeletal pneumaticity probably facilitated the evolution of extremely long necks in some sauropod lineages by overcoming respiratory dead space and reducing mass. In addition, pulmonary air sacs may have conveyed to sauropods some of the respiratory and thermoregulatory advantages enjoyed by birds, a possibility that is consistent with the observed rapid growth rates of sauropods.

Background: The specific characteristic of anatomy and physiology of children cause the risk of radiation effects received when they underwent the interventional cardiology procedures higher than an adult. Purpose: to estimate the stochastic effect risk in a pediatric patient during interventional cardiology procedures. Method: Data collection was performed by placing thermoluminescence dosimeter (TLD) on thyroid, gonad, left and right thoracic areas, and the 5th thoracic vertebrae during interventional cardiology. Result: The results showed that the greatest exposure was received around vertebrae (bone marrow) because of the superimpose X-ray on the vertebrae during the procedures. Conclusion: The greatest probability of stochastic effect that happened was leukemia. Estimation risk ratio of leukemia was 0, 9 % and thyroid cancer was 0,037%.

Individuals with spinal cord injuries above thoracic level 6 experience episodic bouts of life-threatening hypertension as part of a condition termed autonomic dysreflexia (AD). The hypertension can be caused by stimulation of the skin, distension of the urinary bladder or colon, and/or muscle spasms. Transcutaneous electrical nerve stimulation (TENS) may reduce the severity of AD because TENS has been used to inhibit second-order neurons in the dorsal horn. Therefore, we tested the hypothesis that TENS attenuates the hemodynamic responses to colon distension. Eleven Wistar rats underwent spinal cord transection between thoracic vertebrae 4 and 5 (paraplegic, n = 6) or between cervical vertebra 7 and thoracic vertebra 1 (quadriplegic, n = 5). After recovery, all rats were instrumented with a radiotelemetry device for recording arterial pressure. Subsequently, the hemodynamic responses to graded colon distension were determined before and during TENS. During TENS the hemodynamic responses to colon distension were significantly attenuated. Thus TENS may be a preventive approach to reduce the severity of AD in paraplegic and quadriplegic individuals.

To investigate the manner in which cancellous bone in different skeletal sites and within a bone site adapts to strenuous training, 5-wk-old male rats were subjected to intensive treadmill running [80% of maximal O2 consumption (VO2max)] for 11 wk. VO2max, tibia length, and bone mineral density were measured. Histomorphometric analysis was performed in the epiphysis, primary spongiosa (1 zero sp) and secondary spongiosa (2 zero sp) of the contralateral proximal tibia, and the 2 zero sp of thoracic and lumbar vertebrae. VO2max was increased by 39%. No changes were observed in vertebrae. Tibia length, 1 zero sp bone volume, and number of trabeculae were significantly decreased, indicating a retarded longitudinal bone growth. Bone mineral density in the proximal tibia was significantly decreased. In the epiphysis, a trabecular thinning and an increase of trabecular number were shown. In the 2 zero sp, bone volume and number of trabeculae were significantly decreased. The increased total eroded surfaces could indicate an early but transient increase in bone resorption activity. Osteoid thickness was reduced, whereas osteoclast number and osteoid surfaces were unchanged, suggesting that the observed bone loss was mostly due to an impaired osteoblastic activity. In conclusion, 1) strenuous training in young rats reduces longitudinal bone growth and induces bone loss, 2) the cancellous bone adaptation is site specific, and 3) the bone loss is mainly due to decreased osteoblastic activity rather than a global adaptation of bone remodeling.

The primary skeletal structure used by dolphins to generate the dorsoventral bending characteristic of cetacean swimming is the vertebral column. In the vertebral column of the saddleback dolphin Delphinus delphis, we characterize the static and dynamic mechanical properties of the intervertebral joints, describe regional variation and dorsoventral asymmetries in mechanical performance, and investigate how the mechanical properties are correlated with vertebral morphologies. Using a bending machine that applies an external load (N m) to a single intervertebral segment, we measured the resulting angular deformation (rad) of the segment in both dorsal extension and ventral flexion. Intervertebral segments from the thoracic, lumbar and caudal regions of the vertebral column were tested from five individuals. Using quasi-static bending tests, we measured the initial (low-strain) bending stiffness (N m rad-1) as a function of segment position, direction of bending (extension and flexion) and sequential cutting of intervertebral ligaments. We found that initial bending stiffness was significantly greater in the lumbar region than in adjacent thoracic and caudal regions, and all joints were stiffer in extension than is predicted (r2 = 0.554) by the length and width of the intervertebral disc and the length of the cranial vertebral body in the segment. Stiffness in flexion is predicted (r2 = 0.400) by the width of the nucleus pulposus, the length of the caudal vertebral body in the segment and the height of the transverse processes from the ventral surface of the vertebral body. We also performed dynamic bending tests on intervertebral segments from the lumbo-caudal joint and the joint between caudal vertebrae 7 and 8. Dynamic bending stiffness (N m rad-1) increases with increasing bending amplitude and is independent of bending frequency. Damping coefficient (kg m2 rad-2 s-1) decreases with increasing bending amplitude and frequency. Resilience (% energy return) increases from approximately 20% at low bending amplitudes (+/-0.6 degree) to approximately 50% at high bending amplitudes (+/-2.9 degrees). Based on these findings, the dolphin's vertebral column has the mechanical capacity to help control the body's locomotor reconfigurations, to store elastic energy and to dampen oscillations.

Disc degenerative changes are directly or indirectly associated with spinal pain and disability. Literature revealed a high prevalence of disc degeneration in the thoracic region, however thoracic MRI degeneration trends and information on disc biochemical matrix constituents are limited for thoracic discs compared to lumbar and cervical discs. The objective of this thesis was to use MRI to investigate the prevalence of disc degenerative changes affecting the human thoracic spine, and to determine the factors affecting spinal disc biochemical matrix. A 3-point subjective MRI grading scale was used to grade the films. The feasibility of using archived formalin-fixed cadaver material was investigated to analyse collagen and elastin crosslinks. The prevalence of degenerative changes in human thoracic discs and vertebrae (T1 to T12) was determined retrospectively from an audit of 216 MRI cases, using sagittal T1- and T2-weighted MR images. In a subsequent series of ex-vivo studies, human thoracic discs and LF from 26 formalin-fixed and two fresh spines, involving all thoracic levels, were examined macroscopically to determine the degeneration status. Subsequently, disc and ligament tissues were analysed biochemically for collagen (pyridinoline and deoxypyridinoline) and elastin (desmosine and isodesmosine) crosslinks. These crosslinks were extracted from hydrolysed samples by cellulose partition chromatography, and analysed by reverse-phase HPLC. Collagen content was determined using its hydroxyproline content, and proteoglycan content was assayed using a modified DMB assay for chondroitin sulphate. Finally the MRI and macroscopic assessments of thoracic discs, were compared with the biochemical data from two fresh cadaver thoracic spines. The 3-point MRI grading scale had a high inter- (k = 0.57 to 0.78) and intra-rater (k = 0.71 to 0.87) reliability. There were no significant differences in the collagen and elastin content and extent of collagen crosslinks between formalin fixed and unfixed ligament and disc tissues, after 25 weeks of formalin fixation. From the in-vivo MRI series of investigations (n = 216 MRI films), the prevalence of thoracic disc degenerative and vertebral morphological changes revealed significant age, gender and spinal level trends (p < 0.05).Generally, males had a higher propensity for disc degeneration in contrast to females, especially older females, where the trend showed a higher prevalence of osteophytes and vertebral body changes. In particular, the mid and lower thoracic levels have a higher prevalence of degenerative changes, except for osteophytes and anterior vertebral wedging. With increased age, there was a concomitant increase in anterior wedging and bi-concavity and disc degenerative changes except for end-plates. The biochemical investigations on the ex-vivo series of formalin-fixed thoracic discs (n = 303) also revealed significant changes in the disc matrix due to degeneration status, age, gender and spinal regional factors. With increased age, normal disc matrices have significantly lower collagen content and extent of pyridinoline (p < 0.001). In contrast, the degenerated disc matrix revealed significantly higher collagen content and extent of deoxypyridinoline (p < 0.05). These findings suggest that an altered matrix existed in normal ageing discs, which render the disc prone to injury and degeneration over the life span. The higher collagen and deoxypyridinoline in degenerated disc matrices reflects an increase in chondrocyte synthesis, and is also a novel finding, suggesting that they may be used as markers of ageing and degeneration processes. The biochemical investigations on another series of ex-vivo spinal LF tissues (n = 364), revealed that this had a lower collagen and pyridinoline, but significantly higher elastin and deoxypyridinoline compared to spinal discs (p < 0.05). Elastin crosslinks however were difficult to detect in spinal discs, being present in negligible amounts in a few lumbar discs. The elastin crosslinks in the LF were not significantly affected by age, but were significantly higher in calcified, and female ligamentum tissues, and also in the lumbar region (p < 0.05). These MRI prevalence findings enhanced our knowledge of vertebral body and disc degeneration trends in the thoracic region and contributed to the interpretation of MR images for pathology in the human thoracic spine. Information on the associated collagenous and elastic changes in the disc and ligamentum matrices provide original data and insight on the pathogenesis of degeneration in the disc matrix from a biochemical perspective, highlighting gender, age and spinal level influences on the matrix tensile strength and cellular synthetic activities.

This study measures select static and dynamic characteristics of the human mid-thoracic spine, and compares them to previously published data for the thoraco-lumbar and cervical regions. Little information is available on the acute injury threshold for mid-thoracic intervertebral discs. The aim of this study was to characterize injury thresholds for the thoracic spine. Non-destructive combined flexion-compression loading experiments were conducted on 5 fresh human T5-T10 functional spinal units (FSU) at quasi-static and physiologic strain rates, and the resulting load-deflection responses were converted into global and local stiffness. Subsequently, 29 thoracic vertebrae (T5-T10) from 6 spines were subjected to moderate to severe impact loading in flexion. The peak forces and pressures were not statistically different between the thoracic disc levels. However, the mean injury forces and pressures were statistically different from mean failure forces found in the literature for both the lumbar and cervical spine regions, with the thoracic values falling between the cervical and lumbar values.

This work is focused on the evaluation of the dynamic performance of different neck protection devices. In order to evaluate the mechanical response of the safety devices, a multibody model of the human neck has been developed in Matlab™ SimMechanics™. The mechanical behavior of the neck is described in the paper and different injury indices are presented and compared. The information about anatomy and physiology of the cervical spine of the neck has been collected from the literature, with particular focus on the mechanism of damage of vertebrae, disks and soft tissues. The multibody model has been validated against experimental data available in the literature concerning impulsive loads representative of crash phenomena. By means of the presented model, some relevant injury indices are computed for an accident involving a motorcyclist. Since the focus has been set on mild injuries of the neck, the simulated crash should cause a high probability of injuries of the neck together with a low probability of damages of the head while wearing a standard helmet. The performance of neck safety devices that link the helmet with the thoracic-shield are evaluated and compared. For sake of clearness, three types of neck safety devices are considered referencing to US patents: an airbag jacket, a 3D cushion wrapping the motorcyclist’s neck, and a “spring and dampers” system. The airbag jacket has been modeled as a high stiffness and low deformation system by considering the airbag in its fully deployed configuration and by neglecting its dynamic performance during inflation phase. The other safety devices have been modeled as lumped parameters spring-damper systems. A sensitivity analysis on the injury indexes has been performed by changing the stiffness and the damping parameters of these safety systems. The injury indexes collected by simulating the different neck safety systems have been compared.

Degeneration in the spinal structures can be a major source of pain that increases with aging in a roughly linear progression. Pain has been further correlated with the regions of high stress and strain concentrations. Due to difference in the regional anatomy and physiology of the cervical, thoracic, and lumbar levels, their biomechanical response to physiological loadings is different. The fluid egresses outside in the radial direction from nucleus pulposus (NP) to annulus fibrosus (AF) under compression, which generates a hydrostatic pressure against an external applied load. The increased NP pressure, in many clinical cases, results into various abnormal disc pathologies such as protrusions and herniations. Chiropractic care in the management of these spinal dysfunctions uses manual manipulation therapies such as distraction techniques to relieve the disc from high pressure and radial bulging. Despite manual distraction therapy is a three-dimensional force application; major proportion of the load is exerted in the axial upward direction. Although few biomechanical studies have compared the segmental biomechanics under axial traction loads, to the best of our knowledge, there is no study that distinguishes between the behavior of cervical, thoracic, and lumbar segments to these loads. The objective of the present study, therefore, was to investigate that how the biomechanical stresses, that were developed under upper body weight (BW), changes in the various spinal segments (cervical, thoracic, and lumbar) and in the different spinal structures (top vertebra, superior endplate, and disc) when the traction forces were applied as the therapeutic modalities in the chiropractic interventions.