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MUSCULAR SYSTEM (Anatomy 1)
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See also:MUSCULAR See also:SYSTEM (See also:Anatomy 1) . The muscular See also:tissue (See also:Lat. musculus, from a fancied resemblance of certain muscles to a little See also:mouse) is of three kinds: (1) voluntary or striped muscle; (2) involuntary or unstriped muscle, found in the skin, walls of hollow viscera, coats of See also:blood and lymphatic vessels, &c.; (3) See also:heart muscle. The microscopical See also:differences of these different kinds are discussed in the See also:article on CONNECTIVE Tissuas. Here only the voluntary muscles, which are under the See also:control of the will, are to be considered.
The voluntary muscles See also:form the red flesh of an See also:animal, and are the structures by which one See also:part of the See also:body is moved at will upon another. Each muscle is said to have an origin and an insertion, the former being that See also:attachment which is usually more fixed, the latter that which is more movable. This distinction, however, although convenient, is an arbitrary one, and an example may make this clear. If we take the See also:pectoralis See also:major, which is attached to the front of the See also:chest on the one See also:hand and to the upper part of the See also:arm See also:bone on the other, the effect of its contraction will obviously be to draw the arm towards the chest, so that its origin under See also:ordinary circumstances is said to be from the chest while its insertion is into the arm; but if, in climbing a See also:tree, the hand grasps a See also:branch above, the muscular contraction will draw the chest towards the arm, and the latter will then become the origin. Generally, but not always, a
r For See also:physiology, see MUSCLE AND See also:NERVE.muscle is partly fleshy and partly tendinous; the fleshy contractile part is attached at one or both ends to cords or sheets of See also: 1, P.). Every muscle is supplied with blood vessels and lymphatics (fig. 1, v, a, 1), and also with one or more nerves. The nerve See also:supply is very important both from a medical and a morphological point of view. The approximate attachments are also important, because unless they are realized the action of the muscle cannot be understood, but the exact attachments are perhaps laid too See also:great stress on in the anatomical teaching of medical students. The study of the actions of muscles is, of course, a physiological one, but teaching the subject has been handed over to the anatomists, and the results have been in some respects unfortunate. Until very recently the anatomist studied only the dead body, and his one See also:idea of demonstrating the action of a muscle was to expose and then to pull it, and whatever happened he said was the action of that muscle. It is now generally recognized that no See also:movement is so See also:simple that only one muscle is concerned in it, and that what a muscle may do and what it really does do are not necessarily the same thing. As far as the deeper muscles are concerned, we still have only the anatomical method to depend upon, but with the superficial muscles it should be checked by causing a living See also:person to perform certain movements and then studying which muscles take part in them. For a See also:modern study of muscular actions, see C. E. Beevor's Croonian Lectures for 1903 (See also:London, 1904). Muscles have various shapes: they may be fusiform, as in fig. 1, conical, riband-like, or flattened into triangular or See also:quadrilateral sheets. They may also be attached to skin, See also:cartilage or See also:fascia instead of to bone, while certain muscles surround openings which they constrict and are called sphincters. The names of the muscles have gradually grown up, and no settled See also:plan has been used in giving them. Sometimes, as in the coraco-brachialis and thyro-hyoid, the name describes the origin and insertion of the muscle, and, no doubt, for the student of human anatomy this is the most satisfactory plan, since by learning the name the approximate attachments are also learnt. Sometimes the name only indicates some peculiarity in the shape of the muscle and gives no See also:clue to its position in the body or its attachments; examples of this are biceps, semitendinosus and pyriformis. Sometimes, as in the flexor See also:carpi ulnaris and corrugator supercilii, the use of the muscle is shown. At other times the position in the body is indicated, but not the attachments, as in the tibialis anticus and peroneus See also:longus, while, at other times, as in the See also:case of the pectineus, the name is only misleading. Fortunately the names of the describers themselves are very seldom applied to muscles; among the few examples are See also:Horner's muscle and the R, The fleshy belly. to, Tendon of origin. ti, Tendon of insertion. n, Nerve of supply. a, Artery of supply. v, Vein. 1, Lymphatic See also:vessel. P, The patella. muscular See also:band of Treitz. The See also:German anatomists at the Easel See also:conference lately proposed a See also:uniform Latin and See also:Greek nomenclature, which, though not altogether satisfactory, is gaining ground on the See also:European See also:continent. As there are some four See also:hundred transverse wrinkles in the forehead. The anterior, posterior and See also:superior auricular muscles are See also:present but are almost functionless in See also:man. The See also:orbicularis palpebrarum forms a sphincter round the eyelids, which it closes, though there is little doubt that parts of the muscle can See also:act separately and cause various expressions. The See also:side of From A. M. See also:Paterson, See also:Cunningham's See also:Text See also:Book of Anatomy. Additional information and CommentsThere are no comments yet for this article.
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