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Mechanics of one- and two-joint muscles. American Museum novitates ; no. 2319

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dc.contributor.author Bock, Walter Joseph, 1933- en_US
dc.date.accessioned 2005-10-06T16:28:30Z
dc.date.available 2005-10-06T16:28:30Z
dc.date.issued 1968 en_US
dc.identifier.uri http://hdl.handle.net/2246/2529
dc.description 45 p. : ill. ; 24 cm. en_US
dc.description Includes bibliographical references (p. 42-45). en_US
dc.description.abstract "The mechanics of one- and two-joint muscles are described by means of free-body diagrams. Both static and dynamic (rotational and linear) conditions are analyzed. Free-body diagrams treat all the forces acting on bodies and allow analysis of the consequences of these forces; the associated equations are simple summations. D'Alembert's principle is employed (inclusion of a fictitious force or torque) in examples of linear or angular acceleration so that the forces and torques are reduced to an equilibrium and can be treated by the method of statics. Centripetal and tangential forces are included whenever a bone is rotating. Equations are written for examples of one-joint and two-joint muscles. A general three-dimensional model is presented. The use of the notion of first-, second-, and third-class levers is discouraged, because such a classification of lever systems is more misleading than useful. The mechanics of 'spurt' and 'shunt' muscles are analyzed, with special emphasis on the amount of torque produced and the contribution to the needed centripetal and tangential forces. 'Shunt' muscles could produce as mush torque as could 'spurt' muscles muscles; the needed centripetal force may be less than that supplied by the muscles or could be provided by ligaments at the articulation. It is argued that this division of muscles is misleading and even erroneous, and that these terms should be avoided. The contraction of a muscle does not produce a force couple on each bone onto which the muscle attaches, as has been advocated in the earlier literature. The force at the articulation depends on all other forces, real and fictitious, acting on the bone and, except by rare chance, is not equal in magnitude, parallel, and opposite in direction to the muscle force. Two-joint muscle-bone systems are non-static (and non-stable if static) and are indeterminate (the consequences of the muscle force cannot be ascertained merely from a knowledge of the morphology). No simple correlation exists between the relationship of the force vector of the muscle to the longitudinal axis of the central bone and the direction of rotation of the central bone. Some of the advantages and disadvantages of two-joint muscles as compared with one-joint muscles are discussed. A completely satisfactory analysis of these advantages and disadvantages must wait until empirical studies of many two-joint muscle-bone systems have been made. The advantages and disadvantages of free-body diagrams in biomechanical studies are outlined, with the recommendation that all analyses of bone-muscle systems should use free-body diagrams or methods that are clearly derived from free-body diagrams. The strength of such a method is that all the forces acting on each free-body (bone) are included and the consequences of their combined actions can be readily ascertained"--P. 41-42. en_US
dc.format.extent 4102917 bytes
dc.format.mimetype application/pdf
dc.language eng en_US
dc.language.iso en_US
dc.publisher New York, N.Y. : American Museum of Natural History en_US
dc.relation.ispartofseries American Museum novitates ; no. 2319 en_US
dc.subject.lcc QL1 .A436 no.2319, 1968 en_US
dc.subject.lcsh Muscles -- Motility -- Mathematical models. en_US
dc.subject.lcsh Muscle contraction -- Mathematical models. en_US
dc.title Mechanics of one- and two-joint muscles. American Museum novitates ; no. 2319 en_US
dc.title.alternative Mechanics of muscles en_US
dc.type text en_US


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  • American Museum Novitates
    Novitates (Latin for "new acquaintances"), published continuously and numbered consecutively since 1921, are short papers that contain descriptions of new forms and reports in zoology, paleontology, and geology. New numbers are published at irregular intervals.

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