THE PRIMARY VESICAL SPHINCTER

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Abstract
SUMMARY: Evidence has been put forward in recent years that urinary continence depends on urethral length. There are theoretical objections to this hypothesis which are discussed.Nine dogs were investigated under anaesthesia. Six dogs were found to be continent when the urethra was divided at the bladder neck. Three dogs were incontinent and these were found to be suffering from marked prostatic hyperplasia. In four dogs it was possible to remove the full bladder completely after dividing the urethra at the bladder neck and it was shown that the primary sphincter could withstand a pressure of up to 15 cm. of water. It is concluded that the primary sphincter of the bladder is at the internal meatus. We have been unable to show that the posterior urethra is necessary to maintain continence in the normal dog and it is likely that the broad aspects of function at the bladder neck are similar in man.