Book 4 - Self Instructional Manual for Cancer Registrars - SEER ...

UrethraThe urethra is a membranous tube which conveys urine from the urinary bladder to the exteriorof the body.At the proximal end is a circular smooth muscle which surrounds the bladder neck and is knownas the internal sphincter. It is controlled by the autonomic nervous system. The external sphincter ofthe urethra is a circular striated muscle which is under voluntary control. In the female, the externalsphincter is located in the vulva; in the male it is in the glans penis.The urethra differs in men and women:The female urethra is a part of only the excretory system and is approximately 2.5 - 3.0 cm long.The male urethra is a part of both the excretory system and the reproductive system. It has threeregions:• The prostatic urethra which passes through the prostate gland is approximately 2.5 cm long.• The membranous urethra which comprises the external muscular section is approximately1.3 em long.• The penile (spongy or cavernous) urethra which passes through the penis is approximately9.0 - 15.0 cm long.RegionalLYmph NodesThe regional lymph nodes for the urethra are:CommoniliacInternal iliac (hypogastric) including obturatorExternal iliacInguinal (superficial or deep)PresacralMalignant tumors are rare and are almost always transitional cell carcinomas.267