---
title: "Sacral Canal | Anatomy and Physiology I"
description: "Sacral canal is the sacrum's continuation of the vertebral canal, carrying cauda equina nerve roots and helping protect them in Anatomy and Physiology I."
canonical: "https://fiveable.me/anatomy-physiology/key-terms/sacral-canal"
type: "key-term"
subject: "Anatomy and Physiology I"
unit: "Unit 7"
---

# Sacral Canal | Anatomy and Physiology I

## Definition

The sacral canal is the lower continuation of the vertebral canal through the sacrum. In Anatomy and Physiology I, it is the passage that protects the cauda equina nerve roots as they travel toward the sacral opening.

## What It Is

The sacral canal is the continuation of the vertebral canal inside the sacrum. In Anatomy and Physiology I, you can think of it as the lower part of the central bony passage that carries and protects nerve tissue after the spinal cord ends.

The vertebral canal runs through the vertebral foramina of the vertebrae and normally houses the spinal cord. When the column reaches the sacrum, that canal does not just stop abruptly at the top of the bone. Instead, it continues downward as the sacral canal, following the hollow center of the fused sacral vertebrae.

This matters because the spinal cord itself usually ends above the sacrum, but the nerve roots below that point keep traveling. Those descending roots are called the cauda equina, and they pass through the sacral canal before exiting through openings in the sacrum. The sacral canal ends at the sacral hiatus, which is the inferior opening in the posterior sacrum.

The sacral canal also connects with the anterior and posterior sacral foramina, which are the routes nerve structures use to leave the sacrum and reach the pelvis, perineum, and lower limbs. So even though the spinal cord is finished by this level, the sacrum still has an active job in protecting and transmitting neural structures.

A common mistake is to treat the sacral canal like a separate tunnel with a different purpose from the vertebral canal. It is really the same canal continuing through a different region of the spine. The change is mostly anatomical location and shape, not a change in function. In lab, this often shows up when you trace the vertebral column on a model and follow the canal all the way to the sacral hiatus.

## Why It Matters

The sacral canal matters because it connects the vertebral column to the nerves that keep the pelvis and lower body functioning. When you study the spine, you are not just memorizing bones, you are tracing where neural tissue is protected and where it exits the skeleton.

It also helps you make sense of the sacrum as more than a solid wedge of bone. The sacrum has foramina and a canal because it is still part of the body’s nerve pathway. That is why the sacral region shows up in anatomy questions about spinal structure, nerve passageways, and the difference between the spinal cord and the cauda equina.

This term is useful when you compare the vertebral canal above the sacrum with what happens below the end of the spinal cord. It explains why injuries, procedures, or lab identifications in the lower spine can involve nerve roots even after the cord itself has ended.

## Connections

### Vertebral Canal

The sacral canal is the continuation of the vertebral canal after the spinal column reaches the sacrum. If you can identify the vertebral canal on a spine model, you can follow it into the sacrum and see that the same protective passage keeps going. The relationship is one of extension, not a separate structure.

### [Cauda Equina](/anatomy-physiology/key-terms/cauda-equina)

The cauda equina is the bundle of nerve roots that travels through the lower spinal canal after the spinal cord ends. The sacral canal protects those roots as they descend and exit. This connection is a favorite lab and exam link because the canal explains where the cauda equina is located and why it needs space inside the sacrum.

### Sacrum

The sacral canal is a feature of the sacrum, so knowing the sacrum’s shape and fusion pattern helps you locate it. The sacrum forms the back wall of the pelvis and is made of fused vertebrae, which is why the canal is narrower and more specialized than the canal in the mobile vertebral regions.

### [anterior (ventral) sacral foramen](/anatomy-physiology/key-terms/anterior-ventral-sacral-foramen)

The sacral canal does not work alone. Nerve structures within the sacrum pass out through the anterior sacral foramina to reach nearby regions. If you are tracing pathways on a diagram, the canal is the inside route and the foramina are the exits.

## On the AP Exam

A diagram label question may ask you to point out the sacral canal on a vertebral column model or compare it to the vertebral canal above it. You might also need to trace where the cauda equina travels after the spinal cord ends, especially if the question shows the sacrum from a posterior view. In a lab practical, the clue is usually the hollow passage running through the sacrum and ending near the sacral hiatus. If you see a case question about lower spine anatomy, use the term to explain how nerve roots stay protected even after the spinal cord has ended. On quizzes and short answers, the most common task is simple identification plus function: name the structure, say where it is, and connect it to the cauda equina.

## Key Takeaways

- The sacral canal is the continuation of the vertebral canal through the sacrum.
- It protects the cauda equina nerve roots after the spinal cord ends.
- The canal ends at the sacral hiatus, which is the inferior opening of the sacrum.
- It is part of the sacrum’s anatomy, so it shows up in spine and pelvis diagrams.
- A good way to study it is to trace the canal from the vertebral column into the sacrum and then out through the sacral foramina.

## FAQs

### What is the sacral canal in Anatomy and Physiology I?

The sacral canal is the lower continuation of the vertebral canal through the sacrum. It carries and protects the cauda equina nerve roots as they pass toward the sacral hiatus and exit through openings in the sacrum.

### Is the sacral canal the same as the vertebral canal?

Not exactly, but they are directly connected. The vertebral canal continues into the sacrum as the sacral canal, so it is the same passage in a different region of the spine. The function stays the same: protection for neural structures.

### What passes through the sacral canal?

The cauda equina passes through the sacral canal. These are spinal nerve roots, not the spinal cord itself, because the cord usually ends above the sacrum. The canal gives those nerve roots a protected route before they exit the sacrum.

### What is the difference between the sacral canal and sacral hiatus?

The sacral canal is the hollow passage running through the sacrum, while the sacral hiatus is its inferior opening. Think of the canal as the tunnel and the hiatus as the opening at the bottom.

## Related Study Guides

- [7.3 The Vertebral Column ](/anatomy-physiology/unit-7/3-vertebral-column/study-guide/8zeC380r2ZCaoFXC)

## About This Document

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- [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing
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