الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
In this study, a three-dimensional dynamic model of the human elbow joint has been developed. This model increases the functional insight in the mechanical behavior of elbow joint, to assist in diagnosis and treatment of human elbow disorders, and to estimate the load on morphological structures for prevention of injuries. In the model the bones and joints of the upper limb; the forearm, the humerus, the radio-humeral joint, and elbow joint are represented, as well as 15 muscles and 4 ligaments crossing the elbow joint. The equations of motion were obtained by applying Newton’s 2nd law of motion at elbow joint, thus there were 6 equation’s with 30 unknowns. These unknowns were the magnitudes and directions of 15 elbow muscle forces, 4 ligament forces, the moment arms of the muscles and ligaments about the elbow and radio-humeral joints, and the magnitudes of the contact forces. The model was applied to predict the musculoskeletal forces during simple upper limb motion and javelin throw. Morphological data has been obtained from cadaveric studies by Seireg and Arviker. The model has an inverse dynamic mode, in which muscle forces are obtained from the recorded motion and external force. This model can be used to analyze load sharing between the muscles, the bones and the ligaments of the human elbow at any position under any loading conditions. The position of the center of gravity of the upper limb bones and joints were recorded in global coordinates with two digital video cameras, and WINanalyze software was used to analyze the motion, and then the velocities and accelerations of these points were calculated by the software package developed by the author using numerical differentiation technique. The direction cosines of all the muscle forces, ligament forces, the muscle moment arms, and ligament moment arms were found at any instant using the software package developed by the author using Euler’s angles and vector concepts. This package utilized the conventional rigid-body rotation theory to describe the joints orientation as well as to transform the points of origin and insertion for each muscle from its local coordinates to the global coordinates. The GENETIC OPTIMIZATION PACKAGE used for computing the musculoskeletal forces in the human elbow utilized objective function to minimize the resultant contact force at the elbow region. The model was validated utilizing electromyography (EM G) recording for three surface elbow muscles. Most of the model results seem reasonable when compared with the (EMG) results. The model was used to compare between the muscle, ligament, and reaction forces at the human elbow region of two athletes; one professional and one beginner in javelin throw. The effect of the trajectory of the thrower’s upper limb on the distance and on the muscles forces, ligaments forces, and reaction forces was investigated. The javelin throw distance recorded for the professional subject was as twice as that recorded for the beginner subject. The model results showed that the professional subject mainly depended on the major muscles of his upper limb to achieve his longer throw, while the beginner subject did not mainly depend on these muscles