Studies on the Innervation and Physiology of the Pelvic Parts of the Alimentary and Urinary Tracts

Todd, John Kirkland (1961) Studies on the Innervation and Physiology of the Pelvic Parts of the Alimentary and Urinary Tracts. MD thesis, University of Glasgow.

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The experiments described in this thesis represent an attempt to study the role of the pudendal nerve and the structures which it supplies in the mechanisms controlling evacuation and continence. The problem was approached from several directions. First the morphology of the striated sphincters and other related muscles was studied by gross dissection and conventional histological techniques. Then the morphology of the pudendal nerve was investigated in relation to its functiori by means of a quantitative study of its fibre size distribution. The motor function of the pudendal nerve and the outgoing side of the reflexes in which it participates were investigated by electromyography, while its sensory function was studied by direct electrical recording from the individual nerve fibres. Finally the structure of the relevant sense organs was studied using neurohistoIogicaI techniques. The results of these varied investigations form a complete whole. The results of the individual sections have been summarised in detaiI in the text and at this stage I shall only attempt to select those aspects of the findings which seem to me to be most significant. One of the most striking features of the results is the similarity which they indicate between the behaviour of the external sphincters of the anus and of the urethra. This similarity is not surprising in view of the common embryo logical origin of the two muscles. From thqse results the concept emerges that the external sphincter muscles guard against the escape of rectal or bladder contents during periods of high intra-abdominal pressure and during periods when the rectum and bladder are very full. Although both external sphincters have a low grade tonic activity when the animal is at rest, they are not essential for the maintenance of continence at rest ; this is the function of the smooth muscle internal sphincters. An extension of this concept of the function of the external sphincters as guardians of continence during activity, is the realisation that a number of reflexes exist, the effect of which is to maintain continence. The idea that the maintenance of continence is based on a series of reflexes complementary to those described as the basis of defaecation and of micturition, has not, I think, been emphasised before. The results of the nerve recording experiments are complementary to the results of the electromyographic experiments. The findings described in connection with the flow receptor discharges are of interest because of the light they throw on the functions of lamellated sense organs. Although the results fall together neatly, I am well aware of the wide gaps which still remain to be filled. In particular an investigation, using electronic recording methods, of the reflex behaviour of the smooth muscle internal sphincters and of the sensory function of the pelvic nerve would probably be worth while. It is tempting to think of the results of experimental work on animals in relation to the clinical problems of surgery and medicine but it is not certain how valid such a direct transference of results would be in this case since significant species differences exist. Two of the most striking of these differences are the absence of reflex bladder contraction after chronic spinal cord transection in the cat and the apparent absence in man of Barrington's second and seventh micturition reflexes as found in the cat. These differences, however, should not be allowed to obscure the fundamental similarity of the processes in the two species.

Item Type: Thesis (MD)
Qualification Level: Doctoral
Keywords: Medicine, Physiology
Date of Award: 1961
Depositing User: Enlighten Team
Unique ID: glathesis:1961-79415
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 05 Mar 2020 10:01
Last Modified: 05 Mar 2020 10:01

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