The Innervation of Skeletal Muscle

Abstract

This review is limited to a discussi�n of recent advances in studies of the nervous supply of skeletal muscle. It is divided into the following sections: (a) a short list of some recent symposia which will afford the reader reference to a more extended field than that covered by this article, (b) afferent, and (c) efferent supply, and (d) the electromyogram. Most of the ma terial of section d will deal with action potentials from human muscles, both in the normal individual and in patients suffering from a variety of neural or muscular diseases.Neglect or cursory treatment of electromyography in previous volumes of this series is a result of the limitations of space imposed on writers whose interests lie in other special aspects of muscle physiology where the over powering wealth of new material demands critical survey. In addition, however, there does appear on the part of some physiologists the remark ably naive assumption that human physiology is not "basic" and is to be ignored or treated with deference and pity, to be relegated to clinical lore or to journals of "applied" physiology-a lesser breed. Such an attitude per haps reflects our restricted training which induces us towards the grasping of techniques and away from reflections on the broader implications or applications of facts compiled by means of our exquisite craftsmanship.The contributions of medicine and other "applied" sciences to physiology are common knowledge and need not be emphasized here, but inclinations to subdivide physiology away from medicine can only be deplored. DuBois (1), from the vantage point of long and valuable service in many branches of physiology puts the case succinctly, thus:Physiology has no limitations in any discipline that deals with living matter. The more that physiology invades anatomy, clinical medicine, and all other departments, the better it becomes for science as a whole. I t is not the title that makes the physiolo giat, it is the point of view, the mode of thought. GENERALThe proceedings of several symposia of general interest to muscle physiol ogists are now available. A conference under the auspices of the Centre National de la Recherche Scientifique which took place in 1949 has been published in the Archives des Sciences Physiologiques (2). Although much of the conference dealt with the recent work of expert axonologists and syn aptologists, there is enough material concerning the general features of biological membranes, including muscle, drug action, problems of neuro muscular transmission, and muscle innervation to recommend the findings presented even to those with strictly "muscular" interests. It would appear 139 Annu. Rev. Physiol. 1953.15:139-164. Downloaded from www.annualreviews.org Access provided by Lancaster University -UK on 02/05/15. For personal use only.Quick links to online content Further ANNUAL REVIEWS

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“…Neurons integrate synaptic potentials and may transmit information to other neurons or to muscle fibres via action potentials (e.g., Bullock, 1951;Fetcho, 1991). In muscle fibres, the synaptic potentials generated at the neuromuscular junction may lead to muscle contraction (e.g., Hodes, 1953;Fatt, 1954). A single action potential causes a brief and weak twitch of a muscle fibre (e.g., Hodes, 1953;Hunt and Kuffler, 1954).…”

“…In muscle fibres, the synaptic potentials generated at the neuromuscular junction may lead to muscle contraction (e.g., Hodes, 1953;Fatt, 1954). A single action potential causes a brief and weak twitch of a muscle fibre (e.g., Hodes, 1953;Hunt and Kuffler, 1954). Larger muscle forces are produced by recruiting multiple fibres, and by increasing the frequency of action potentials, leading to temporal summation of contractive force (e.g., Hunt and Kuffler, 1954).…”