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Spinal Cord and Reflexes
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
In humans, the vertebral column normally consists of 33 vertebrae divided into five subdivisions (Figure 11.1), based on some distinguishing characteristics of the vertebrae in each subdivision. The five subdivisions are, rostrally to caudally: Cervical, or neck, region comprising 7 vertebrae, denoted as C1 to C7. The C1 vertebra supports the skull, and the C2 vertebra serves as a pivot for C1.Thoracic, or chest, region comprising 12 vertebrae, denoted as T1 to T12. These vertebrae support the 12 pairs of ribs, which are joined ventrally at the sternum, or breastbone.Lumbar, or lower back, region comprising 5 vertebrae, denoted as L1 to L5.Sacral, or thigh, region comprising 5 fused vertebrae (the sacrum) having a roughly triangular shape. The sacrum articulates laterally with the hip bones. The vertebrae in this region are denoted as S1 to S5.Coccyx, or tailbone, region comprising 4 fused, rudimentary vertebrae.
A novel neural network method using radial basis function for effective assessment of stiffness index on lumbar disc degenerative subjects
Published in Automatika, 2023
C. K. Sreeja, V. N. Meena Devi, M. K. Aneesh
Osteoarthritis stiffness causes pain when the bones are rubbed against each other. Wearing down of the disc occurs on ageing which is a normal process. Most people have disc degeneration after the age of 40 but not with pain. Low back pain is a leading severe health problem, which finally results in hospitalization and increased risk of the financial burden for its treatment and management [1]. Lumbar disc degeneration (LDD), which includes disc herniation [2], spinal column stenosis, spondylosis and spondylolisthesis, is the major reasons for disability. The onset and progression of LDD is influenced by genetics, lack of physical exercise, changes in body composition, a high BMI, unbalanced food, body weight, stress, obesity and poor vascular supply and the like. Over the past few decades, obesity has become an independent predictor of back pain and its intensity, which is linked to degenerative discs in the lower back, sciatica and other lumbar disorders [3].
Effects of backrest and seat-pan inclination of tractor seat on biomechanical characteristics of lumbar, abdomen, leg and spine
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Qichao Wang, Yihuan Huo, Zheng Xu, Wenjie Zhang, Yujun Shang, Hongmei Xu
The spine plays various roles in supporting the trunk, protecting the internal organs, controlling human movement and protecting the spinal cord. The adult spine consists of 26 vertebrae, including seven cervical vertebrae (C1–C7), 12 thoracic vertebrae (T1–T12), five lumbar vertebrae (L1–L5), one sacral vertebra and one caudal vertebra from the top to the bottom. The load of spine in different parts is the sum of the weight of the above limbs, muscle tension and external load. Therefore, the spine gradually widens from the top to the bottom, which is in line with the gradual increase in spinal load. The thoracic vertebra is the most important part of human spine, playing important roles in maintaining the stability and driving the movement of human upper limbs. The lumbar spine is located at the bottom of the spine, acting as a junction of the movable segment and the fixed segment. It bears a large load and is the most frequent site for the occurrence of lumbar occupational diseases. Based on these facts, this study selected some thoracic segments and the whole lumbar segment as the objects for analysis.
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).