Male catheterization, three stenoses, two bends. Where are they?

There are 3 physiological strictures and 2 physiological curves in the process of catheterization, so it is necessary to adjust the strictures and curves during the catheterization process. The 3 strictures are located at the external urethral opening, the urethral membrane and the internal urethral opening, while the two curves and the pubic curve and the pubic curve are anterior. The pubic curve can be corrected after lifting the penis, while the pubic curve position is fixed. The angle of the pubic curve does not change with the movement of the external genitalia. Therefore, after passing through 3 strictures and 2 bends, lift the penis first, correct the anterior pubic curve during the catheterization process, moderately force through the inferior pubic curve and its 3 strictures until urine is seen, and then insert the catheter into the bladder about 4- 5 cm syringe balloon. At this time, it is necessary to insert the urinary catheter into the bladder for about 4-5cm to inflate the balloon, otherwise the balloon may still stay in the posterior urethra. If the balloon is inflated rashly, it may cause damage to the posterior urethra.