MUSCULAR ACTION (VOLUNTARY AND INVOLUNTARY) 327 



Fig. 67 (continued). 



contract where the bohis first touched it. The rule is, that the oesophagus always oontraots behind the bolus ; the part in front of 

 the bolus opening at the same time. In no other way could the bolus be transmitted to the stomach. There is a double power at 

 work in swallowing ; a centripetal, closing, contracting movement behind the bolus, and a centrifugal, opening, dilating movement 

 in front of it. As all parts of the oesophagus are invested with the double power, and the contracting and dilating portions change 

 places, a most efficient steady downward movement is provided for the downward passage of the bolus. 



The movements of the oesophagus in swallowing are the precursors of those occurring in the stomach, sphincters, rectum, 

 heart, bladder, and uterus. 



The oesophagus is to be regarded as a typical involuntary muscle, and, as such, its movements are worthy of very special study. 

 It combines in itself all the peculiarities of muscular activity. It is not dominated by the will nor by nervous arrangements in 

 any form. It is an independent, self-acting, spontaneous muscle— its primary function being to seize and transmit food whenever 

 presented to it. It forms part of a working system. It is for the head and hands to procure and present the food. When food 

 is presented to the oesophagus, it at once becomes aggressive and seizes it. It does not wait to be jogged into activity by 

 artificial stimulation, which stimulation, as explained, could not produce alternate closing and opening of its several portions. 

 The oesophagus is a highly specialised portion of the alimentary canal. It is an original construction, and finds a place in the 

 organisms in which it occurs from the outset. It is a spontaneous and self-acting mechanism. One can swallow air and fluids 

 when no bolus is present. Without an oesophagus and alimentary canal none of the higher animals could exist.' As showing the 

 importance of the oesophagus one has only to realise that its double centripetal and centrifugal powers, which enable it to close 

 or contract at one part while it opens or dilates at another part, foreshadow the movements of the hollow viscera generally, such 

 as the heart, lungs, &c., and of the hollow viscera with sphincters, such as the stomach, rectum, bladder, and uterus. The 

 CESophagus occupies a unique position because of its fundamental nature and its numerous important relations. It is virtually 

 endowed with universality of movement, and a careful study of it forms a fitting introduction to all those structures in which 

 rhythmic movements occur (the Author, 1867). 



B. Portion of the human duodedum, or first part of the small intestine, showing the valvulse conniventes. The valvulse (c, d) 

 project into the interior of the gut in two segments which interdigitate and overlap. They form part of an obstructive system 

 which has for its object the delaying of food in its downward passage. They have great significance when viewed in connection 

 with sphincters, whose precursors or predecessors they are. Their distinguishing feature is their arrangement in symmetrical pairs, 

 which interdigitate and overlap where they meet. A similar arrangement is seen in the lower portion of the oesophagus of the 

 cat when inverted. The valvulse are arranged spirally, and not circularly, as is usually stated. They cross where they meet very 

 obhquely, as happens in the muscular fibres of the pyloric valve (see c, d of Fig. 0), (the Author, 1867). 



C. Pyloric end of the human stomach {a, h), showing the minute or ultimate construction of the pyloric valve (c, d). The 

 valve consists of two sets of muscular fibres which overlap at the angles. They enclose a small elliptical aperture. They are not 

 composed, as is generally believed, of ciiralar fibres : indeed there are no circular fibres either in the stomach or sphincter. The 

 fibres usually figured and described as circular are the terminal loops of figure-of-8 fibres arranged in a more or less continuous 

 layer. The pyloric valve forms a narrow slit or opening which no power possessed by the muscular walls of the stomach could 

 forcibly open. As a matter of fact it opens or dilates spontaneously when the body of the stomach closes or contracts. This is 

 true of all sphincters. The structure of the cardiac sphincter (d of Fig. B) gives the key to that of all the other sphincters (the 

 Author, 1867). 



D. Vertical section of the pyloric end (a, h) of the human stomach ; showing the pyloric valve (c) from the inside. This valve 

 is formed by a duplication or doubling in of the entire walls of the stomach, and is very strong. It projects into the stomach as 

 the valvulse conniventes project into the duodenum. Only the half of its small aperture is seen. The sphincter, as in C, opens up 

 or dilates spontaneously when the stomach closes or contracts (the Author. 1867). 



E. The muscular fibres of the human stomach as dissected by the Author. Seen from the lesser curvature anteriorly. Shows 

 radiating muscular fibres, portions of several layers and the formation of the cardiac sphincter (not hitherto described), a, Portion 

 of oesophagus ; /, root of oesophagus with fibres radiating anteriorly and posteriorly {h, h') in the direction of the pylorus (b) ; 

 c, sulcus indicating position of the pyloric valve ; d, e, great muscular bands crossing very obliquely, anteriorly, and posteriorly, and 

 overlapping to form the cardiac sphincter. By the contracting of these bands the root of the oesophagus (/) is readily obliterated. 

 (J, Portion of the so-called circular layer. 



For a more extended account of the stomach and its sphincters, see Plates cii. and ciii. 



§ 59. Muscular Action (Voluntary and Involuntary), as bearing on Locomotion, Respiration, Circula- 

 tion, Alimentation, Urination, Defaecation, and Parturition. 



Normal muscular action is from within and not from without. It is the result of inherent endowment and 

 vitality. It is not caused by artificial external stimulation, and this is where, it appears to me, modern physiology 

 has made a wrong departure. Modern physiology attempts to work muscle from the wrong side, and has to assume 

 that it is irritable or excitable ; that artificial stimulation and normal nerve action are one and the same thing ; 

 that a large amount of the work performed by muscle is due to elasticity ; that muscle is always on the stretch or 

 in a tonic condition — no real interval of repose being ever allowed to it ; that flexor muscles when they shorten or 

 contract drag out or forcibly extend and elongate the extensor muscles and w'ce versd, and so of the pronator and 

 supinator muscles, abductor and adductor muscles, &c. 



That muscle does not require to be goaded into activity by external artificial stimulation is proved by muscular 

 action as a whole, and by the action of the heart in particular. The movements of the heart are inherent, fundamental, 

 and rhythmic in character. In the chick, where the heart is composed of a mass of nucleated cells, they take place 

 in the absence of muscles, nerves, and even blood. No external or internal stimulation is required, and there is 

 no trace of irritability or excitability in the cells forming the heart. The opening and closing movements of the heart 

 are both vital ; there is no opportunity for elasticity coming into play, neither is forcible distension possible, seeing 



' In eases of constriction or partial obliteration of the oesophagus from any cause the patient can be fed by means of a flexible tube, but this 

 is never satisfactory, and is of course impossible in a state of nature. 



