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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.
Influence of morphological variations on cervical spine segmental responses from inertial loading
Published in Traffic Injury Prevention, 2018
Jobin D. John, Narayan Yoganandan, Mike W. J. Arun, G. Saravana Kumar
Studies have shown that lower cervical spine segments exhibit hyperextension under postero-anterior inertial loading (Grauer et al. 1997; Ivancic and Xiao 2011; Yoganandan et al. 2013). The anterior longitudinal ligament is commonly injured in hyperextension (Davis et al. 1991). The anterior longitudinal ligament stretch ranged from 0.1 to 0.3 in this study. In a previous study, the mean anterior longitudinal ligament stretch of the C5–C6 segment at 3.5 g loading was reported to be 0.2 ± 0.13 (Ivancic et al. 2004). The current study showed that the magnitudes of this ligament stretch are highly dependent on the orientation of the spine segment. The straighter spine sustained larger magnitudes of stretch (Figure 4). Because this ligament is well integrated with the outer annulus fibers of the disc, hyperextension injuries such as disc separation from the endplates in the anterior region can be expected in a straighter spine (Curatolo et al. 2011; Mercer and Bogduk 1999). The straighter curvature of the lower cervical spine in females (Been et al. 2016; Klinich et al. 2004) may result in greater risk of hyperextension-induced injury under this loading mode.