---
title: "Pudendal Nerve | Anatomy and Physiology"
description: "Pudendal nerve is the sacral plexus nerve that carries motor and sensory signals to the perineum, external genitalia, and external urethral sphincter."
canonical: "https://fiveable.me/anatomy-physiology/key-terms/pudendal-nerve"
type: "key-term"
subject: "Anatomy and Physiology I"
unit: "Unit 25"
---

# Pudendal Nerve | Anatomy and Physiology

## Definition

The pudendal nerve is a major nerve from the sacral plexus that supplies sensation and voluntary muscle control in the perineum, external genitalia, and external urethral sphincter.

## What It Is

The pudendal nerve is the main somatic nerve of the perineum in Anatomy and Physiology I. It comes from the sacral plexus, usually through spinal nerve roots S2 to S4, and then travels to the pelvic region to carry both sensory and motor signals.

What makes it stand out is that it does not just provide feeling. It also controls voluntary muscles in the pelvic floor, especially the external urethral sphincter. That sphincter is the muscle you consciously tighten to hold urine in. Because the pudendal nerve supplies it, the nerve is part of the body system that lets you delay urination until the right time.

It also carries sensory information from the external genitalia and parts of the perineum. In other words, it helps the brain register touch, pressure, and pain from that region. That sensory side matters in both normal function and clinical cases, because irritation or compression of the nerve can cause numbness, pain, or altered sensation.

The course connection to urine transport is the micturition reflex. When the bladder fills, stretch signals help trigger urination, the detrusor muscle contracts, and the external urethral sphincter relaxes so urine can leave the body. The pudendal nerve is the nerve that gives you voluntary control over that sphincter, so it acts like the conscious override during bladder filling. If you choose not to urinate yet, the pudendal nerve keeps the sphincter contracted.

Its pathway through the pudendal canal, also called Alcock’s canal, is a classic anatomy detail because that route can make it vulnerable to compression or entrapment. If the nerve is damaged, you can see problems with urinary continence, fecal continence, or sexual function. So this nerve sits at the crossroads of sensation, voluntary control, and pelvic floor coordination.

## Why It Matters

The pudendal nerve shows up any time Anatomy and Physiology I connects nervous system anatomy to pelvic function. It is one of the clearest examples of a somatic nerve controlling a specific body region, so it helps you separate voluntary control from automatic smooth muscle activity.

It also ties together several course ideas at once: sacral plexus anatomy, pelvic floor muscles, urinary continence, and the micturition reflex. If you can trace what the nerve supplies, you can explain why a person can postpone urination, why injury can affect bladder control, and why sensory loss in the perineum changes normal function.

In a lab or quiz setting, this term often appears in diagrams of the pelvis, nerve pathways, or urinary anatomy. It can also show up in case-based questions about incontinence, pelvic trauma, childbirth injury, or nerve compression. Knowing the pudendal nerve gives you a path from structure to function instead of treating the pelvic floor as a random list of muscles and nerves.

## Connections

### [Sacral Plexus](/anatomy-physiology/key-terms/sacral-plexus)

The pudendal nerve branches from the sacral plexus, so this plexus is the starting point for its anatomical story. If you know where the sacral plexus sits and which spinal roots feed it, you can place the pudendal nerve in the bigger map of lower-limb and pelvic innervation. It is the source, while the pudendal nerve is one of the major branches.

### [External Urethral Sphincter](/anatomy-physiology/key-terms/external-urethral-sphincter)

This is the main muscle the pudendal nerve controls for voluntary urine retention. The bladder may be filling automatically, but the external urethral sphincter is what you consciously keep contracted until you decide to void. When that nerve supply is disrupted, holding urine becomes much harder.

### Pelvic Floor Muscles

The pudendal nerve helps innervate the muscular support system of the pelvic floor. That connection matters because the pelvic floor stabilizes the pelvic organs and contributes to continence. If you are tracing function, think of the pudendal nerve as part of the neural control that keeps the pelvic floor working in a coordinated way.

### [Continence](/anatomy-physiology/key-terms/continence)

Continence is the ability to hold urine or feces until an appropriate time, and the pudendal nerve is part of that control. It helps keep the external sphincter contracted between bathroom trips. When the nerve is compressed or injured, loss of continence is one of the clearest signs that something in pelvic nerve control is off.

## On the AP Exam

A quiz question might ask you to identify which nerve provides voluntary control of the external urethral sphincter or which structure can be damaged in pelvic floor injury. In a diagram, you may need to trace the pudendal nerve from the sacral plexus to the perineum and name the region it supplies. In a case question, look for symptoms like urinary incontinence, fecal incontinence, or perineal sensory loss and connect them to pudendal nerve damage. If the bladder is filling but the person is delaying urination, that voluntary hold is a good clue that the external urethral sphincter and its pudendal innervation are involved.

## Pudendal Nerve vs Internal Urethral Sphincter

These are easy to mix up because both help control urine release, but they work differently. The pudendal nerve controls the external urethral sphincter, which is skeletal muscle under voluntary control. The internal urethral sphincter is smooth muscle at the bladder neck and is controlled involuntarily by the autonomic nervous system.

## Key Takeaways

- The pudendal nerve is a sacral plexus nerve that supplies the perineum, external genitalia, and pelvic floor structures.
- It carries both sensory information and motor signals, so it is involved in feeling and in voluntary muscle control.
- Its most tested function in urine transport is control of the external urethral sphincter, which lets you consciously hold urine.
- Because it runs through the pudendal canal, it can be compressed or injured, leading to pain, numbness, or continence problems.
- It links nervous system anatomy to the micturition reflex, pelvic floor function, and sexual function.

## FAQs

### What is the pudendal nerve in Anatomy and Physiology?

The pudendal nerve is a major nerve from the sacral plexus that supplies the perineum and external genitalia. It carries sensory signals and also controls voluntary muscles like the external urethral sphincter. That makes it central to continence and pelvic floor function.

### What does the pudendal nerve control?

It controls sensation in the perineal region and motor function in pelvic floor muscles, especially the external urethral sphincter. That sphincter is the muscle you consciously contract to hold urine. It also contributes to function in the external genitalia and anal region.

### How is the pudendal nerve related to urination?

The pudendal nerve gives you voluntary control over the external urethral sphincter during bladder filling. When you decide to urinate, that sphincter relaxes so urine can pass through the urethra. If the nerve is damaged, holding urine can become difficult.

### Is the pudendal nerve the same as the internal urethral sphincter?

No. The pudendal nerve controls the external urethral sphincter, which is skeletal muscle and voluntary. The internal urethral sphincter is smooth muscle and is controlled involuntarily by autonomic nerves. That difference is a common A&P comparison question.

## Related Study Guides

- [25.2 Gross Anatomy of Urine Transport ](/anatomy-physiology/unit-25/2-gross-anatomy-urine-transport/study-guide/YFKBmItDqCHASdLY)

## About This Document

Canonical Fiveable pages are available as Markdown at the same path plus `.md`.

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- [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing
- [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`)
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