---
title: "Spina Bifida | Intro to Brain and Behavior"
description: "Spina bifida is a neural tube defect where the spinal column does not close fully, affecting spinal cord development in Intro to Brain and Behavior."
canonical: "https://fiveable.me/introduction-brain-behavior/key-terms/spina-bifida"
type: "key-term"
subject: "Intro to Brain and Behavior"
unit: "Unit 6"
---

# Spina Bifida | Intro to Brain and Behavior

## Definition

Spina bifida is a neural tube defect in which the embryonic spinal column does not close fully around the spinal cord. In Intro to Brain and Behavior, it shows what can go wrong during neurulation.

## What It Is

Spina bifida is a birth defect that happens when the lower part of the neural tube does not close completely during early embryonic development. In Intro to Brain and Behavior, you meet it as a clear example of how a tiny error in neurulation can shape the spinal cord and the nerves that connect the brain to the body.

The basic mechanism is simple, but the consequences can vary a lot. During neurulation, the neural plate folds inward and seals into the neural tube, which later becomes the brain and spinal cord. If the tube does not close all the way in the region that forms the spine, part of the spinal cord or its coverings can remain exposed or form abnormally.

That is why spina bifida is called a neural tube defect. The term literally points to a “split spine,” but the real issue is developmental closure failure, not a broken spine after birth. The severity depends on how much of the tube failed to close and whether meninges, spinal cord tissue, or both are involved.

The mildest form is spina bifida occulta, where the defect may be hidden under skin and cause few or no obvious symptoms. More serious forms include meningocele, where the meninges protrude, and myelomeningocele, where spinal cord tissue is involved too. Myelomeningocele is the form most likely to cause motor, sensory, bladder, or bowel problems because the spinal cord is directly affected.

Cause is usually described as multifactorial. Genetics, maternal folate status, and environmental factors can all affect risk. That is why folic acid before and during pregnancy is emphasized in developmental neuroscience and health education, because folate supports the cell division and growth needed for normal neural tube closure.

A useful way to think about spina bifida in this course is as a before-and-after marker. Before closure, the embryo is still setting up the nervous system. After closure should happen, the neural tube becomes the structural starting point for the brain and spinal cord. When closure fails, you can trace the later disability back to one missed step in early development.

## Why It Matters

Spina bifida shows how early brain and spinal cord development can shape later movement, sensation, and bodily control. It connects a microscopic embryology process to real-world outcomes like leg weakness, reduced sensation, or problems with bladder and bowel function.

It also gives you a clean example of causation in developmental neuroscience. You can trace the sequence from neural induction, to neural plate formation, to neurulation, to neural tube closure, and then to the structures that fail when closure does not happen normally. That chain is the kind of mechanism Intro to Brain and Behavior keeps returning to.

The term also helps when a class discusses prevention and risk. Folic acid is not just a nutrition fact here, it is tied to nervous system development before a pregnancy is even recognized. That link makes spina bifida a strong example of how biology, environment, and timing all matter together.

If your course touches neurological disorders, spina bifida is a reminder that not all disorders begin after birth. Some begin during the earliest stages of nervous system formation, when the spinal cord and brain are still being built.

## Connections

### [Neural tube](/introduction-brain-behavior/key-terms/neural-tube)

Spina bifida is a defect of the neural tube, specifically when closure fails in the region that becomes the spine. If you picture the neural tube as the early blueprint for the central nervous system, spina bifida is what happens when that blueprint does not seal correctly along the back.

### Neural induction

Neural induction is the step that tells part of the ectoderm to become nervous tissue instead of skin. Spina bifida happens later than induction, but it still belongs in the same developmental chain because a problem during early nervous system formation can lead to later closure defects.

### Neurulation

Neurulation is the folding and closing process that turns the neural plate into the neural tube. Spina bifida is one of the clearest examples of what can go wrong during this process, especially when the tube does not fully close in the spinal region.

### [Neural crest cells](/introduction-brain-behavior/key-terms/neural-crest-cells)

Neural crest cells form near the edges of the closing neural tube and later migrate to many parts of the body. They are not the same thing as the defect itself, but they sit in the same early developmental window, so they often come up in the same unit.

## On the AP Exam

A quiz item may show an embryo diagram and ask you to identify where closure failed, or it may describe symptoms and ask which type of spina bifida fits best. You may also explain the sequence from neural plate to neural tube and point out that a closure problem during neurulation can affect the spinal cord. In written answers, the move is to connect structure to function: if the lower spinal cord is involved, look for motor, sensory, or autonomic problems below the lesion. If folic acid comes up, tie it to prevention rather than treatment. For case questions, use severity clues to distinguish occulta from meningocele or myelomeningocele.

## spina bifida vs Neural Tube

Spina bifida is not the whole neural tube. The neural tube is the early embryonic structure that becomes the brain and spinal cord, while spina bifida is a defect that happens when part of that tube fails to close, usually in the spinal region. If a question asks for the structure itself, answer neural tube. If it asks for the closure defect, answer spina bifida.

## Key Takeaways

- Spina bifida is a neural tube defect caused by incomplete closure of the spinal column around the spinal cord during early development.
- The severity ranges from hidden, mild forms to severe forms that can affect movement, sensation, and autonomic function.
- It belongs in the neurulation unit because the problem starts when the neural tube is supposed to form and seal.
- Folic acid intake before and during pregnancy lowers risk because early neural development depends on normal cell growth and closure.
- A good explanation of spina bifida connects embryology to later physical symptoms, not just the name of the disorder.

## FAQs

### What is spina bifida in Intro to Brain and Behavior?

Spina bifida is a neural tube defect that happens when the spinal column does not close fully around the spinal cord during embryonic development. In Intro to Brain and Behavior, it is used to show what can go wrong during neurulation and how early development affects later nervous system function.

### Is spina bifida the same as a neural tube defect?

Spina bifida is one type of neural tube defect, not the entire category. Neural tube defects include problems that happen when the neural tube does not close normally, and spina bifida refers specifically to the lower, spinal end of that closure failure.

### What causes spina bifida?

There is usually no single cause. Risk is linked to a mix of genetic factors, maternal folate deficiency, and environmental influences, which is why folic acid is often discussed as a prevention measure in developmental neuroscience.

### How do you tell the different types of spina bifida apart?

Occulta is the mildest form and may be hidden under the skin. Meningocele involves protrusion of the meninges, while myelomeningocele involves spinal cord tissue too and is usually the most severe. The more neural tissue involved, the more likely there are major neurological effects.

## Related Study Guides

- [6.1 Neural induction and neurulation](/introduction-brain-behavior/unit-6/neural-induction-neurulation/study-guide/JJyt8ljXQKn35nwf)

## About This Document

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

- [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns
- [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`)
- [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`)

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