The sphincter is a muscle that closes a duct by the effect of its contraction. Continence, urination, defecation but also control of digestion or blood flow, etc. So many functions that are performed by the many sphincters of our body. Explanations.

A sphincter is a circular (or ring-shaped) skeletal muscle located around a natural duct (such as the digestive tract or a blood vessel). The sphincter can dilate and contract allowing the passage of a substance from one organ to another (through the conduit or the orifice it surrounds) while preventing its return. This constrictor muscle can completely seal an organ.

The sphincter can be a striated muscle. In this case, its control is voluntary and controlled by the somatic nerves (which allow movement and perception of sensations).

But sometimes the sphincter is a smooth muscle the contraction of which is involuntary and controlled by the autonomic nervous system (which is responsible for functions not subject to will, such as digestion or respiration). The functioning of sphincters is linked to the nervous system. Like the latter, upon death, the sphincters relax.

Some sphincters perform their functions thanks to their anatomy and more particularly thanks to their circular muscle thickening, we are talking about anatomical sphincters. Other sphincters act indirectly through the contraction of surrounding muscles, we are talking about functional sphincters.

There are a very large number of sphincters in humans. Some are microscopic in size, for example pre-capillary sphincters (small circular muscles that allow the control of blood circulation in the blood capillary vessels). Among the main sphincters, we could cite:

We suspect a pathology of a sphincter, when the latter no longer performs its function of opening and closing the canal or the orifice it surrounds. Depending on the location, a sphincter dysfunction can lead to:

• Anal, rectal or bladder incontinence;
• Spasms (involuntary contractions) which can alter certain functions such as swallowing;
• Un gastroesophageal reflux or GERD (especially in case of cardiac gap).

Sphincter dysfunction can be traumatic or neurological in origin.

Treatment varies depending on the severity of the sphincter disorder:

• Perineal rehabilitation passive (by electrostimulation) or active (by breathing and weight training exercises as well as by the biofeedback method) can be used to treat anal incontinence. These treatments can be practiced by a physiotherapist, a midwife or by the patient himself in self-treatment;
• Surgical intervention For example : the placement of an artificial sphincter in the event of urinary incontinence, placement of a urethral sphincter prosthesis consisting of an inflatable silicone sleeve placed around urethra and connected to a pump; surgical section or sphincterotomy in case of anal fissure (section of the anal sphincter) or the presence of stones in the common bile duct (section of the sphincter of Oddi).

In the event of symptoms suggestive of a sphincter disorder (incontinence, esophageal spasms, gastroesophageal reflux disease, etc.), it is recommended that you consult your doctor who can refer you to a specialist if he deems it necessary.

For a sphincter disorder, your doctor has told youinstruct a gastroenterologist and proctologist (for digestive sphincters) or a urosurgeon (for urethral sphincters).

These specialists will perform a clinical examination as well as additional imaging examinations depending on the location of the failing sphincter:

• colonoscopy;
• fiberscopie;
• rectoscopy;
• anuscopy;
• ultrasound;
• etc.