STUDY ON THE CLOSING MECHANISM OF THE URETHRA

Abstract

1) According to Dr Okabis previous experiments, the change of inner pressure of the anus which was schown at the time interruption of the urination and of termination of the urination was indicated by the Kymographion as curve. Considering from this curve and the anatomical relation of perineum muscles, he had an illation that the closing of the front part of the urethra will be completed by the pushing of the bulbus urethrae at the right angles to the urethra, which is caused by the musculus sphincter ani and the musculus bulbocavernosus contracting in well-balanced strength. If this illation is right, a special closing pressure should be added to the urethra at the time of interruption of the urination and of termination of the urination.
I, with a view to prove and measure the existence of the said pressure, made the experiments on 50 men and found that the closing pressure at the time of the interruption of the urination and of the termination of the urination is 3-8cm H₂O.
2) By the fact that the bulbus urethrae projects at the part of the perineum at the time of the interruption of urination and termination of the urination and from the anatomical point of view of the perineum muscle, I had an illation as to the change of pressure of the inner part of the bulbus urethrae at the time of interruption of the urination and of termination of the urination. That is, in consideration of the direction of M. bulbocavernosus which consists of three layers, if the musculus sphincter ani contracts in the well-balanced strength with the M. bulbocavernosus, the bulbus urethrae is transformed at the cross section into the ellipse in shape on a long axis of sagital direction. At this time, the central pressure of the inner part of the bulbus urethrae is zero and the strength tending upwards works at the upper part of the bulbus urethrae and on the contrary, the strength tending downward from the upper part at the lower part. The urethra running through the upper part of the bulbus urethrae, accordingly, is closed by the strength tending upwards.
3) In my experiments, the myogram of the M. bulbocavernosus at the time of interruption of the urination and of termination of the urination, when induced by the surface electrode, showed a wary curve just like that of an irregular interference voltage.
The amplitude of vibration was about 200μV and its vibration lasted around a second. In case that the urination was consciously interrupted, its vibrating time was slightly shorter, although the myogram was almost the same as that of the above-mentioned case.
According to these facts, contraction of the M. bulbocavernosus was surely confirmed.