Internal urethral orifice

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Internal urethral orifice

The internal urethral orifice is an anatomical structure located within the urinary system of the human body. It is the opening at the junction of the urinary bladder and the urethra, through which urine passes from the bladder into the urethra for excretion.

Anatomy

The internal urethral orifice is situated at the neck of the urinary bladder. In males, it is located at the base of the prostate gland, while in females, it is positioned anterior to the vagina. The orifice is surrounded by the internal urethral sphincter, a smooth muscle that controls the release of urine from the bladder.

Function

The primary function of the internal urethral orifice is to regulate the flow of urine from the bladder into the urethra. The internal urethral sphincter plays a crucial role in this process by contracting to retain urine in the bladder and relaxing to allow urine to pass through the orifice during micturition (urination).

Clinical Significance

Disorders of the internal urethral orifice can lead to various urinary system conditions. For instance, urethral stricture can cause narrowing of the orifice, leading to difficulty in urination. Additionally, urinary incontinence may occur if the internal urethral sphincter fails to function properly.

Related Structures

• External urethral orifice
• Urethra
• Urinary bladder
• Prostate gland (in males)
• Vagina (in females)

See Also

• Urinary system
• Micturition
• Internal urethral sphincter
• Urethral stricture
• Urinary incontinence