what is an urethra
The urethra is the passageway between the bladder and the external part of the body, which allows urine to be excreted from the body. The urethra is a thin, fibromuscular tube that begins at the lower opening of the bladder and extends through the pelvic and urogenital diaphragms to the outside of the body, called the external urethral orifice. The urethra also connects the to the ductus deferens in males, for the ejaculation of sperm. There is a sphincter at the upper end of the urethra, which serves to close the passage and keep the urine inside the bladder.