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The urethra is a tube that connects the urinary ladder to the urinary meatus for the removal of Urine from the body of both females and males. In human females and other Primates, the urethra connects to the urinary meatus above the Vagina, whereas in Marsupials, the female's urethra empties into the urogenital sinus. Females use their urethra only for Urination, but males use their urethra for both urination and 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, receives its Nerve supply by the sympathetic division of the autonomic nervous system. The internal sphincter is present both in males and females. [from Wikipedia]
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