urinrörssphinctern

The urinrörssphinctern, also known as the urethral sphincter, is a muscular ring that controls the flow of urine from the bladder through the urethra. There are typically two sphincters involved: the internal urethral sphincter and the external urethral sphincter.

The internal urethral sphincter is an involuntary smooth muscle located at the junction of the bladder and the urethra. It is primarily controlled by the autonomic nervous system and remains contracted to prevent urine leakage during bladder filling. When the bladder is full, signals from the bladder trigger relaxation of this sphincter, allowing urine to enter the urethra.

The external urethral sphincter is a voluntary skeletal muscle located further down the urethra. It is under conscious control and can be voluntarily contracted to prevent urination, even when the bladder is full. This allows individuals to postpone voiding until a socially appropriate time and place.

The coordinated action of these two sphincters is crucial for maintaining continence, the ability to control urination. Dysfunction of either sphincter can lead to urinary incontinence, a condition characterized by involuntary leakage of urine. Causes of sphincter dysfunction are varied and can include nerve damage, muscle weakness, or certain medical conditions. Understanding the anatomy and function of the urinrörssphinctern is important for diagnosing and treating issues related to urinary control.