The urethra (pl.: urethras or urethrae) is the tube that transports urine from the bladder to the urethral meatus of the penis or vulva in placental mammals, and in males also transports semen during ejaculation. The external urethral sphincter is a striated muscle that allows voluntary control over urination. The internal sphincter, formed by the involuntary smooth muscles lining the bladder neck and urethra, is innervated by the sympathetic division of the autonomic nervous system and is found both in males and females.

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