The Striped Compressor of the Prostatic Urethra

SUMMARY Henle's external vesical sphincter is studied in transverse and longitudinal sections with reference to the surrounding tissues. It arises by two horns from the muscle of the bladder neck, whose smooth fibres are replaced by striped, and from the dense connective tissues beside the prostate. Its fibres sweep round the sides and ventral surfaces of the prostatic urethra, lying between the vertical fibres of the pubovesical muscles, and the transverse smooth muscle of the urethra. As the words “external sphincter” now refer to a different muscle, the sphincter of the membranous urethra, and as it does not form a complete sphincter, the muscle is referred to as the compressor of the prostatic urethra. Probably it takes little part in continence under conditions of rest, but helps to prevent stress incontinence, brings about reflux after voluntary interruption of micturition, empties the urethra and reapposes the mucous surfaces after micturition and helps to ejaculate semen.