What Is a Sphincter Muscle?
Generally, a sphincter muscle is a muscle that encircles the passages and openings of the body. The sphincter is often a band like structure that can be found in different parts of the body including the eyes, mouth, stomach, intestine, and the bladder. A sphincter muscle may contract or relax to regulate the flow or passage of body’s secretions and matter taken in as food.
Sphincter muscles are involved in many bodily functions. For instance, the sphincter muscle around the pupil of the eye can shrink the pupil in response to bright light. The sphincter of Oddi is considered to have a significant role in controlling the flow of bile and pancreatic juice into the duodenum, which is a part of the small intestine. Sphincters that open and close the urethra can help with bladder control. Small sphincters occurring around the blood vessels may moderate blood pressure.
The esophagus, which is a tube that links the mouth to the stomach, typically has upper and lower sphincters. The upper sphincter normally blocks the food or liquid in the esophagus from passing back into the throat. The lower sphincter relaxes and opens only when food or liquid is ingested, and thus can help safeguard the esophagus from stomach acid and bile.
A sphincter muscle may be consciously controlled or it may act involuntarily. Normally, nerves transmit signals from the brain to contract or relax the sphincter muscles. The last section of the digestive system or the anus usually has two sphincters. The internal sphincter typically cannot be controlled at will and it keeps the anus closed until one has to expel the body’s waste products. One could control the external sphincter to prevent the involuntary release of waste or to excrete the waste as the case may be.
Various factors may affect the functioning of the sphincter muscles. Sphincters can weaken as one advances in age. Sometimes a sphincter muscle might get injured as can occur during childbirth, for instance. In some health conditions, nerves that communicate with the sphincter muscles can get impaired resulting in muscle dysfunction.
One could experience some health issues if a sphincter muscle doesn’t work as well or is defective. A problem with urethral sphincter may cause urinary incontinence. Weakening of the esophageal sphincter might lead to heartburn as the acidic juices from the stomach rise into the esophagus causing a burning sensation. Sometimes sphincter muscles about the rectum don’t function properly affecting one's bowel control. In such cases, sphincter muscle surgery is one of the options that may be recommended to treat the problem.
There are exercises that could assist in strengthening certain sphincter muscles. For example, a set of exercises that work the urinary and anal sphincters may help make them stronger, improve muscle function, and control incontinence. Generally, one needs to do the exercises regularly over a prolonged period to benefit.
Written by Archana Khambekar
