The bladder sphincter is made up of two muscles that control the release of urine from the bladder through the urethra. If the bladder were a reservoir, then the bladder sphincter would be the dam that holds back water and controls when it is released. The bladder sphincter is made up of two muscles, the internal and external sphincter muscles.
- The internal sphincter muscle is located at the opening of the bladder to the urethra. It is a smooth, involuntary muscle. Because of its location, it is also primary muscle prohibiting the release of urine.
- The external sphincter muscle surrounds the area of the urethra outside the bladder. It is the secondary muscle in control of urine flow. It is made of skeletal muscle and is a voluntary muscle.
Both muscles function in a similar fashion. When one relaxes the voluntary muscle, the involuntary muscle relaxes as well. When these muscles are relaxed, they open up allowing for urine to flow out of the bladder through the urethra and out the body. When these muscles are contracted, they keep urine in the bladder. Given the functions of the bladder sphincter, it is understandable the important role it plays in urinary continence. Damage or weakening of these muscles can also be a main cause for urinary incontinence.
Urinary incontinence is the loss of bladder control. It is a common yet embarrassing problem. It can be as mild as releasing a small amount of urine when you laugh or sneeze, or as serious as having the urge to urinate come on so strong and fast that you don’t have time to get to a bathroom. Problems with the bladder sphincters can cause several different forms of incontinence.
One form of urge incontinence occurs when the urethra can’t hold back urine in the bladder and the bladder sphincters relax uncontrollably.
Stress urinary incontinence is another common issue. In this case, stress or damage to the sphincters or surrounding muscles can cause urinary incontinence. This is common in women after childbirth, or in men after prostate surgery or radiation therapy. Neurogenic bladder dysfunction occurs when trauma or disease of the central nervous system causes a person to lose control of their bladder sphincter muscles.
Although issues caused by malfunctioning bladder sphincters can be embarrassing, there are a variety of treatment options available. The option that works best–whether it be lifestyle changes, medication, or surgery–depends on the patient and their overall medical history. Urologists work to understand their patient’s unique needs and develop the best plan to treat their bladder problems. For more information, visit the Advanced Urology Institute website.