In men and women, around the internal urethral orifice, the detrusor muscle thickens to form the internal sphincter.

无论男性女性，尿道内口的逼尿肌增厚，形成尿道内括约肌。

The urethra is a thin muscular tube that drains urine from the bladder, starting from the internal urethral orifice to the external opening.

尿道是细的肌性管道，从膀胱引流尿液；起于尿道内口，终于尿道外口。

The floor of the bladder has a smooth triangular region called the trigone region - with two corners at the ureterovesical junctions and the third corner being the internal urethral orifice, where the bladder meets the urethra.

膀胱的底部有一个光滑的三角形区域，称为膀胱三角；其中两角顶端为输尿管-膀胱连接处，第三角定点为尿道内口；膀胱与尿道通过尿道内口相通。