China
Africa
Explore chapters and articles related to this topic
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.
Biomechanics of spinal trauma
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
Brian D. Stemper, Narayan Yoganandan
Vertebrae increase in size inferiorly from cervical to lumbar regions and demonstrate region-dependent anatomical characteristics. Cervical vertebrae, C1 to C7, are the smallest of the spinal column. Lower cervical vertebrae, C3 to C7, demonstrate approximately consistent anatomy. The most distinct feature is its anteriorly-oriented vertebral body. The bodies are oval-shaped in the horizontal plane. The saddle-shape of the bodies in the coronal plane are due to the bilateral uncinate processes. All vertebral bodies consist of trabecular bone and cortical shell. Superior and inferior surfaces have endplates, consisting of a thin shell of horizontally-oriented cortical bone. Postero-laterally oriented pedicles connect the vertebral body to the articular pillars, known as lateral masses. The two articular pillars are the second most massive portions of the vertebrae. Superior and inferior surfaces are flat and oriented at approximately 45° in the sagittal plane. Postero-medially oriented laminae connect the pillars to the spinous process. The posterior edge of the vertebral body, pedicles, pillars, and laminae enclose the vertebral foramen, through which the spinal cord traverses. Spinous processes extend posteriorly and are approximately one-half of the anterior-posterior vertebral length. The posterior-most extent of spinous processes C3 to C6 bifurcates into two tubercles. C7 spinous process does not bifurcate and is more prominent than other vertebrae, a feature evident on lateral x-rays.
A modified finite element dummy model of Chinese adult male used for train collision simulations
Published in International Journal of Rail Transportation, 2023
Zhenhao Yu, Shaodong Zheng, Kai Liu, Zhipeng Gao, Longmao Zhao, Lin Jing
Figure 14 shows the Von-Mises stress contour maps of cervical vertebrae at maximum flexion (t1 and t3, as shown in Figure 13(b)) and maximum extension (t2 and t4, as shown in Figure 13(b)). It is suggested that the Von-Mises stress of the modified model and THUMS-AM50 are mainly distributed in the cone of C4-C7 cervical vertebrae at the time of maximum flexion. The maximum Von-Mises stresses of the modified model and THUMS-AM50 are 1.46 MPa and 1.95 MPa, respectively. The relative error is +33.6%. Similarly, the Von-Mises stresses of the modified model and THUMS-AM50 are mainly distributed in the spinal process of C4-C7 cervical vertebrae at the time of a maximum extension. The maximum Von-Mises stresses of the modified model and THUMS-AM50 are 1.65 MPa and 2.15 MPa, respectively. The relative error is +30.3%.
Importance of intervertebral displacement for whiplash investigations
Published in International Journal of Crashworthiness, 2020
Roman Bumberger, Memis Acar, Kaddour Bouazza-Marouf
Yamazaki et al. (2000) used the mathematical head-and-neck model developed by De Jager [63] which was originally only validated for frontal and lateral impacts. The model consists of nine rigid bodies to represent the head (C0), the seven cervical vertebrae (C1–C7) and the first thoracic vertebra (T1). Each vertebra is connected to its adjacent vertebrae by spring-damper elements to mimic all cervical soft tissues. These elements were adjusted by Yamazaki et al. to improve the response of the model for rear-end impact simulations. The experimental data for the validation was taken from the JARI study, but data from only one volunteer was used. The intervertebral rotations of the model agreed well with the volunteer data, however, intervertebral translation motions were not validated.
A multi-body model for comparative study of cervical traction simulation – development, improvement and validation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Lawrence K. F. Wong, Zhiwei Luo, Nobuyuki Kurusu, Keiji Fujino
The structure of the cervical spine model is illustrated in Figure 2. Eight rigid bodies are used to represent the head and the seven pieces of the cervical vertebrae (C1-C7). Each intervertebral joint is modelled as non-linear viscoelastic material in flexion and extension. It is built as a “free joint” element in the simulation. The “free joint” element allows stiffness and damping properties to be assigned to the joint with required number of degrees of freedom of motion. Since traction force is applied symmetrically during cervical traction, lateral shear (i.e. translation along x-axis) is not modelled in the simulation. Also, since the inclined and sitting positions do not cause axial rotation and lateral bending to the cervical spine, these two rotation directions are not modelled. In other words, only anterior/posterior shear, tension/compression and flexion/extension are modelled in the simulation. For the ligaments, a spring element at the spinous process is used to represent the combined behavior of all four posterior ligaments at each cervical level. Since we assume that the subject is in a relaxed state during cervical traction and muscle activation is minimal, thus muscle components are not included in the model. A detailed overview of the joints in the cervical spine is shown in Figure 3.