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Biomechanics of spinal trauma
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
Brian D. Stemper, Narayan Yoganandan
Several ligaments interconnect each vertebral segment. Ligaments are elastic bands made up of collagen and elastin fibres arranged in parallel (Nachemson et al., 1968). Five primary ligaments interconnect each segmental level: anterior and posterior longitudinal ligaments, ligamentum flavum, interspinous ligament, and facet joint capsular ligament. The longitudinal ligaments run continuously along anterior and posterior vertebral body surfaces from cervical to lumbosacral regions. The anterior longitudinal ligament is a broad ligament covering most of the vertebral body anterior surface. The posterior longitudinal ligament is similar to its anterior counterpart, although about one-third as wide. Individual deep fibers of these liagments traverse a single disc and superficial fibers may traverse several segments. The ligamentum flavum, or yellow ligament, spans between adjacent laminae. The thickness of the ligamentum flavum increases inferiorly. The interspinous ligament spans between spinous processes of adjacent levels. The ligamentum flavum and interspinous ligaments are not continuous as fibers connect opposing surfaces of adjacent vertebrae. Capsular ligaments along with synovial membranes and synovial fluid form the facet joints. These synovial joints consist of fluid between the adjacent articular processes. The synovial membrane contains the fluid, and the capsular ligament forms a band around the membrane. The membrane and ligament are collectively known as the joint capsule. Posterior to the spinous processes is the supraspinous ligament in thoracic and lumbar regions and the ligamentum nuchae in the cervical region. The nuchae extends from the occipital bone of the cranium to the posterior extents of cervical spinous processes. The thin supraspinous ligament runs continuously along the posterior extents of spinous processes from C7 to the sacral region.
Finite element modelling and biodynamic response prediction of the seated human body exposed to whole-body vibration
Published in Ergonomics, 2023
Kaizhan Gao, Zhifei Zhang, Hongwei Lu, Zhongming Xu, Yansong He
Referring to the database of human anatomy and anthropometry provided by the Poser software (Poser Pro 11, Smith Micro Software Inc, Santa Cruz, CA, USA), the .obj file of the lumbar spine geometry in standing posture was obtained, as shown in Figures 1(a,b). The .obj file of the lumbar spine was exported from Poser and converted into a .stl file in 3ds Max software (V2015, Autodesk, USA), and the modelling was completed in the commercial software Hyperworks (V2017.1, Altair, USA). The lumbar spine consists of the vertebral bodies (including cortical bone and cancellous bone), intervertebral discs, and ligaments. There are seven types of ligaments, including the anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), capsular ligament (CL), ligamentum flavum (LF), interspinous ligament (ISL), supraspinous ligament (SSL), and intertransverse ligament (ITL), as shown in Figure 1(c). The intervertebral disc consists of nucleus pulposus, annulus fibrosis, endplates (0.8 mm), and collagen fibres, as shown in Figure 1(d). The ratio of the cross-section area of the nucleus pulposus was assumed to be 44% of the disc area (Kong and Goel 2003).
Finite element mechanics analysis of lumbar spine with normal and varying degrees of herniated lesions under different working conditions and material properties
Published in Mechanics of Advanced Materials and Structures, 2022
Yu Hui, Ze-xun Zhou, Jing Du, Bo Wu, Wei Huang
The integrated model includes the human spine lumbosacral segment L4, L5, anterior longitudinal ligament, posterior longitudinal ligament, ligamentum flavum, supraspinous ligament, interspinous ligament and intervertebral disk. The vertebrae are divided into cortical bone and cancellous bone. The intervertebral disk is divided into annulus fibrosus and nucleus pulposus according to physiological parameters. The annulus fibrosus accounts for 52% of the total volume of the intervertebral disk, and the nucleus pulposus accounts for 48%. The light blue area in the figure is the L4 segment of vertebra, and the red area is the L5 segment. The yellow area is the human intervertebral disk, and the gray area is the main ligament soft tissue in the vertebral body. The entire model included 4,359,234 nodes and 4,259,840 units of different types.
Biomechanical modeling of spinal ligaments: finite element analysis of L4-L5 spinal segment
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Shabnam Hamidrad, Masoud Abdollahi, Vahid Badali, Mohammad Nikkhoo, Sadegh Naserkhaki
Ligaments included anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), capsular ligament (CL), intertransverse ligament (ITL), ligamentum flavum (LF), supraspinous ligament (SSL), and interspinous ligament (ISL). Four different approaches were utilized to model the ligaments resulting in four different models as summarized in Table 2 and depicted in Figure 1. Uniaxial truss elements were used in three of the models and 2 D shell element was used in one of them. In the 3 D model, space trusses were structured in longitudinal, anteroposterior, mediolateral and diagonal directions which were connected together in space joints three dimensionally (Figure 1(d)). Initially two layers of parallel longitudinal trusses were constructed between two vertebrae at the position of each ligament. Then, they were divided to approximately 1 mm elements. Finally, diagonal and transverse elements were generated between every two adjacent joints of these elements.