Anatomy and biomechanics of the spinal column and cord (original) (raw)
Related papers
2011
Biomechanics, the application of mechanical methods to biological systems, is a rapidly growing area of immense importance. The ability to influence the ''lifetime''of parts of the human body or to offer adequate replacements in the case of failure has a direct influence on our entire well-being. This becomes increasingly important during old age when joints must be replaced in order to guarantee an adequate mobility of the various components of the human body.
Examination Questions and Answers in Basic Anatomy and Physiology, 2018
The study of mechanics involves the appreciation of the mass of a body and its inertia and of the interaction of mass and gravity to produce the object's weight. Newton's laws describe forces and their interaction with masses to alter their motion. Examples of unbalanced forces (those that will change an object's motion) are gravity, friction and the contraction of skeletal muscle. The bones of the skeleton may be thought of as levers that turn around the synovial joints (the fulcra) when skeletal muscles provide the effort force. The load force is the weight of the limb being moved along with whatever is being held by or being made to move by the limb. Many configurations of bone, muscle and joint that occur in the body can be described as third class lever systems, and hence as "inefficient". That is, the effort force produced by contracting muscles is greater than the load force to be shifted. Correct and safe patient handling procedures (manual handling), involves minimising the amount of lifting by asking the patient to move themselves-and instructing them how to. If the carer is required to shift a patient, manual handling also involves minimising the use of weak muscles and bones, such as those of the back. Instead, the strong muscles of the legs are used; the length of the load arms are minimised (by getting your centre of gravity close to the load), and friction is minimised by using a slide sheet or board. Furthermore correct technique requires that stability is maintained (by keeping your centre of gravity over your base of support), and that the help of gravity, and other health care workers, is enlisted.
Poisson’s Ratio and Strain Rate Dependency of the Constitutive Behavior of Spinal Dura Mater
Annals of Biomedical Engineering, 2010
Knowledge of the mechanical behavior of spinal dura mater is important for a number of applications including the experimental and computational modeling of physiological phenomena and spinal cord trauma. However, mechanical characterization of dura mater is relatively sparse and is further compounded by the use of the tangent modulus as the sole measure of stiffness. This study aims to provide a more complete description of the mechanical properties of spinal dura mater, including the effect of strain rate. Bovine dura mater was tested under uniaxial tension in both the longitudinal and the circumferential directions at three different strain rates; 0.01, 0.1, and 1.0 s À1 . An Ogden model was fitted to the resulting stress-stretch data. The morphology of the dura mater was assessed using Sirius red and H&E staining. No significant effect of the strain rate was found for the Ogden model parameters. Longitudinal specimens were significantly stronger and more deformable than circumferential samples, probably due to the structural arrangement of the collagen fibers. At low strains, however, the circumferential specimens were stiffer than the longitudinal ones. The findings of this study will allow more complete representations of the spinal dura mater to be developed.
Influence of ligament stiffness on the mechanical behavior of a functional spinal unit
Journal of Biomechanics, 2004
Data on the stiffnesses of spinal ligaments are required for analytical studies on the mechanical behavior of spinal segments. Values obtained experimentally vary widely in the literature. A finite element model of an L3/L4 functional spinal unit was used to determine the influence of ligament stiffness on intersegmental rotation and forces in the ligaments. The lowest values for ligament stiffness selected from the literature were used in one set of calculations, and the highest values were simulated in a second set. The nonlinear model was loaded with pure moments of 7.5 and 15 Nm in the three main anatomical planes. The mechanical behavior of the functional spinal unit was strongly influenced by ligament stiffness. In some cases, a ligament with low stiffness does not carry any load, while the same ligament with high stiffness has to carry a high load. This indicates that finite element models of spinal segments have to be validated and that a realistic quantitative prediction of ligament forces is extremely difficult. r
Measurement of a spinal motion segment stiffness matrix
Journal of Biomechanics, 2002
The six-degrees-of-freedom elastic behavior of spinal motion segments can be approximated by a stiffness matrix. A method is described to measure this stiffness matrix directly with the motion segment held under physiological conditions of axial preload and in an isotonic fluid bath by measuring the forces and moments associated with each of the six orthogonal translations and rotations. The stiffness matrix was obtained from the load-displacement measurements by linear least squares assuming a symmetric matrix. Results from a pig lumbar spinal motion segment in an isotonic bath, with and without a 500 N axial preload, showed a large stiffening effect with axial preload.