Hello, the male urethra has different diameters, and there are three strictures, which are located at the internal urethral orifice, the membranous orifice and the external urethral orifice. When the penis is slack and drooping, the urethra has two bends: ① pubic downward curvature: it is located below the pubic symphysis and sunken forward, which cannot be changed because of the fixed position of the urethra; ② Protrusion of pubic bone: It is located at the anterior lower part of pubic symphysis, and it is depressed backward lower part.