There is a small striated musculotendinous sling of the bulbocavernosus muscle which extends from the anterior and lateral surfaces of the proximal bulbous urethra. This structure is known as musculus compressor nuda, which may indent the proximal bulbous urethra on dynamic retrograde urethrography or, rarely on voiding uretherography.

It causes a convex symmetric cone shape formation to the proximal bulbous urethra and the cone tip is the point at which the bulbous urethra enters the urogenital diaphragm to continue as the membranous urethra.

It should not be mistaken for stricture formation.