Various nerves control bladder and bowel function. They are responsible for moving food through the digestive system, controlling the anal sphincter, and emptying the bladder and bowel.

These nerves include the spinal cord, cauda equina, pudendal nerves, and the enteric nervous system, which is a complex network of nerves present in the walls of the digestive tract.

If nerves that control the bladder or bowel become damaged, it can result in urinary or fecal incontinence. Conditions that may cause this include herniated discs, spinal cord injuries, and cauda equina syndrome.

Read on to learn more about the nerves that control bladder and bowel function and the conditions that can affect them.

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Many nerves are involved in bladder and bowel control. Some of the main nerves responsible for this include:

  • The spinal cord: This is the main pathway for nerve signals between the brain and the bladder and bowel. The spinal cord lies inside the bones of the spine.
  • The cauda equina: This is a group of nerve roots at the lower end of the spinal cord. They provide sensation and control of movement to the lower part of the body, including the bladder and bowel.
  • Pudendal nerves: There are pudendal nerves on the left and right sides of the body within the pelvis. They affect fecal and urinary control.
  • Pelvic parasympathetic nerves: These nerves begin at the sacral level of the spinal cord, which is the lowest part of the spine above the coccyx. They stimulate the bladder and relax the urethra.
  • Lumbar sympathetic nerves: These nerves of the lower region of the spine stimulate the base of the bladder and urethra.

The body has several nerves that work together to coordinate bladder function. They allow the bladder to hold or expel urine as appropriate by telling the bladder muscles to tighten or release.

The cauda equina

The cauda equina is a group of nerves and nerve roots that stems from the lower end of the spinal cord and helps control the bladder. If the nerves become damaged, people may experience urinary retention or incontinence.

Pelvic parasympathetic nerves

Doctors may also refer to these nerves as the pelvic splanchnic nerves. They arise from the sacral level of the spinal cord and trigger bladder contraction during urination.

Pudendal nerves

The pudendal nerves stimulate the pelvic floor muscles, the anal sphincter, and pelvic organs.

There is a pudendal nerve for each side of the body, arising from the sacral plexus, the lowest part of the spine above the tailbone. The sacral plexus is a complex network of nerves situated at the back of the pelvis.

Lumbar sympathetic nerves

The lumbar sympathetic nerves are a bundle of nerves that lie in front of the spine in the lower back. They carry sympathetic nerve signals from the lower extremities that control urine storage in the bladder.

Several nerves help control bowel function, digestion, and excretion. This includes the pudendal nerves and the cauda equina, which provides sensation and control of movement to the lower part of the body, including the bowel, anus, and perineum.

However, the primary nerve pathway that controls bowel function is the enteric nervous system (ENS), a complex network of nerves present in the walls of the gastrointestinal tract. It controls the wave-like contractions that push food through the gut, also known as peristalsis.

The ENS also regulates the opening and closing of the sphincters, which are the muscle bands that control the passage of food waste. Usually, signals from the brain and spinal cord control this. For example, the ENS may receive signals to speed up or slow down digestion based on emotional stress.

If necessary, the ENS can also function independently. For example, if a person’s brain no longer controls peristalsis, the ENS would still work to push food through the digestive system.

Several conditions can affect the nerves that control bowel or bladder function.

Cauda equina syndrome

Cauda equina syndrome (CES) may develop if the cauda equina nerves become compressed. It is a rare but serious condition.

Because the cauda equina sends sensations to the bladder, bowel, and legs, people with CES can lose muscle sensation, resulting in loss of bladder and bowel control.

In a 2017 survey of 75 people with CES, urinary problems were a symptom for 92% of the participants. This includes mild incontinence and being unable to fully feel the sensation of passing urine. Almost three-quarters of the respondents also experienced fecal dysfunction.

Spinal cord injury

Spinal cord injuries can disrupt communication between the brain and the nerves of the spinal cord that control the bladder and bowel. This can result in a neurogenic bladder or neurogenic bowel. A person with a neurogenic bladder may experience:

Symptoms of neurogenic bowel include:

Neuropathy

Neuropathy is nerve damage or dysfunction. For example, diabetic neuropathy is nerve damage that occurs due to diabetes. People with this condition may develop diabetic bladder dysfunction, including overactive bladder, incontinence, and needing to urinate during the night.

A number of other conditions can also lead to neuropathy. Some people may develop neuropathy and urinary incontinence following surgery to remove the prostate, for instance.

Yes, back problems can cause bowel or bladder issues. Herniated disks are the most common cause of CES. Disk herniation happens if the flexible disk between the vertebrae, or spinal bones, slips out of place.

A damaged or pinched nerve in the spine can also lead to problems controlling the bladder.

A person experiencing bowel or bladder incontinence should speak with their doctor. It is particularly important to do so if the problem is new or the individual also has neurological symptoms such as weakness, numbness, or tingling in the legs.

If incontinence is sudden and severe and accompanied by the above symptoms, it may be a medical emergency. A person should dial 911 or the number of the nearest emergency department.

Conditions such as CES are serious, and the person may require surgery to prevent permanent loss of bowel or bladder function.

There are many nerves that control bladder and bowel function, including the spinal cord, cauda equina, ENS, and more. If these nerves become damaged, a person may experience incontinence, difficulty controlling the urge to urinate or defecate, urinary or fecal frequency, urinary tract infections, or constipation.

Conditions such as cauda equina syndrome can result from a herniated disc. A person may require emergency surgery to prevent lasting nerve damage. Therefore, anyone who develops bowel or bladder incontinence should speak with a doctor urgently to rule out any potentially serious causes.