The navicular fossa is a short dilated portion of (the spongy (or cavernous or penile) portion of) the male

urethra The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...

within the

glans penis In male human anatomy, the glans penis or penile glans, commonly referred to as the glans, (; from Latin ''glans'' meaning "acorn") is the bulbous structure at the Anatomical terms of location#Proximal and distal, distal end of the human penis ...

just proximal to the

external urethral meatus The urinary meatus (, ; : meati or meatuses), also known as the external urethral orifice, is the opening of the penis or vulva where urine exits the urethra during urination. It is also where semen exits during male ejaculation, and other fluids ...

. The roof of the fossa is especially dilated, forming a lacuna; medical instruments being inserted into the male urethra should initially be directed towards the floor of the fossa so as not to get snagged at the fossa. It is one of three dilations of the male urethra (the other two occurring at the

prostate The prostate is an male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found in all male mammals. It differs between species anatomically, chemica ...

, and the

bulb of penis The bulb of penis is the proximal/posterior bulged end of the (unpaired median) corpus spongiosum penis. Together with the two crura (one crus on each side of the bulb), it constitutes the root of the penis. It is covered by the bulbospongiosu ...

). The wall of the navicular fossa is the only part of the urethra that is lined with stratified squamous epithelium (instead of the

transitional epithelium Transitional epithelium is a type of stratified epithelium. Transitional epithelium is a type of tissue that changes shape in response to stretching (stretchable epithelium). The transitional epithelium usually appears cuboidal when relaxed and ...

that is typical for the urinary tract). During development, the glans of the penis is initially solid but cannulates to give rise to the navicular fossa.

References

External links

* - "The Male Pelvis: The Urethra" * {{Portal bar, Anatomy Male urethra