Know Your Brain
Start with brain organization, major regions, and their broad roles.
Open resource →First use requires internet. Reference images and brain surfaces load from their credited repositories. The simulation runs locally. After the assets load, use Save offline copy to make a single HTML file with all assets embedded.
Spatial anatomy
1. Rotatable cerebral cortex
A solid, shaded surface made from the left and right fsaverage5 pial meshes, rather than a point cloud. Drag to rotate, scroll or use the slider to zoom, and separate the hemispheres to explore their medial surfaces.
Loading anatomical surface data
Retrieving two small surface files from the Nilearn reference dataset. Images and the action-potential simulation load independently.
fsaverage5 · cerebral cortex onlyWaiting for surface data
Starting viewer...
Data: FreeSurfer fsaverage5 pial surfaces distributed with Nilearn (10,242 vertices and 20,480 triangles per hemisphere). This is a group-reference cortical reconstruction, not an individual patient scan. The medial wall does not reveal the thalamus or corpus callosum. Study those in the next anatomy section. Dataset documentation.
Gross neuroanatomy
2. Lateral brain anatomy
Compare an original anatomical atlas plate with a photograph of preserved human brain tissue. The plate shows the lateral surface of the left hemisphere, with the frontal pole at the left and occipital pole at the right.
Johannes Sobotta, Textbook and Atlas of Human Anatomy (1908), plate 626. Original atlas engraving, not a generated diagram. Source and public-domain notice. Historical terminology appears in the plate; the notes use current terms.
Sectional anatomy
3. Midline and deep brain anatomy
Use the detailed sagittal plate to identify the corpus callosum, ventricular spaces, brainstem and cerebellum. Compare it with an actual sectioned brain. Not every deep structure lies on the midline.
Gray's Anatomy (1918), plate 720. Original anatomical engraving with fine tissue detail. Source and public-domain notice. "Intermediate mass" refers to the interthalamic adhesion; the hippocampus is not shown in this true midline view.
Cellular anatomy
4. Neuron structure under the microscope
Begin with actual light microscopy, switch to electron microscopy to see myelin, and use the separate medical rendering to relate the cell body, dendrites, axon and terminals. These are different specimens and image types, not successive zooms into one neuron.
Interactive physiology
5. Action potential simulation
The graph displays membrane voltage over time. The membrane diagram shows Na+ and K+ channels and the direction of ion movement during each stage.
Membrane voltage−70 mV
StageResting
Na+ channelsClosed
K+ channelsClosed
Resting
Threshold
Depolarization
Peak
Repolarization
Hyperpolarization
What is happening?
At rest, the inside of the neuron is negative relative to the outside. If threshold is reached, voltage-gated Na+ channels open rapidly and Na+ enters. Then Na+ channels inactivate, K+ channels open, and K+ exits to repolarize the membrane.
Teaching model: the action-potential waveform and voltage values are illustrative, not a fitted biophysical model. Ion gradients are maintained over time by transport mechanisms, including the Na+/K+ pump; the pump does not produce the rapid falling phase of each spike. OpenStax explanation.
Continue learning
6. Neuroscience resources
BrainFacts
Beginner-friendly articles and educational brain resources.
Open resource →OpenStax: Action Potentials
Resting voltage, ion channels, threshold, and action-potential phases.
Open resource →Neuroscience, Purves et al.
A foundational neuroscience textbook hosted by the National Library of Medicine.
Open resource →BrainBrowser
Explore additional surface and volume data in a research-oriented viewer.
Open resource →Allen Brain Atlas
Move beyond gross anatomy into spatial and cellular brain datasets.
Open resource →DNA Learning Center: 3D Brain App
An additional learning resource for exploring brain regions on mobile devices.
Open resource →Surface Dataset Documentation
Read about the pial surfaces used in this page and their available resolutions.
Open resource →Nervous System Overview
OpenStax chapter on nervous tissue, neurons, and glia.
Open resource →Knowledge check
7. Short quiz
1. Which lobe is primarily associated with visual processing?
2. Which ion usually drives the rapid upstroke of a classic neuronal action potential?
3. Which structure is especially important for coordination and motor learning?
Sources, image credits and model scope
The images are published anatomical illustrations or photographs, not AI-generated anatomy. They are displayed without recoloring or anatomical alterations. Resizing is for display only. Open any gallery image's source link for the original and its licensing details.
Johannes Sobotta, Textbook and Atlas of Human Anatomy (1908), plate 626. Original atlas engraving, not a generated diagram. Source and public-domain notice. Historical terminology appears in the plate; the notes use current terms.
Human brain after formalin fixation. Photograph by Jensflorian; source, CC BY-SA 4.0. Preserved anatomical specimen; image shown without recoloring.
Gray's Anatomy (1918), plate 720. Original anatomical engraving with fine tissue detail. Source and public-domain notice. "Intermediate mass" refers to the interthalamic adhesion; the hippocampus is not shown in this true midline view.
Sagittally sectioned human brain preserved in formaldehyde, Universidade de Taubaté museum. Photograph by Themium / Davi Vieira Peixoto; source, CC0. The front of this specimen is to the right, unlike the atlas plate.
Light microscopy of Purkinje neurons in a dog cerebellum, not a human sample. Lennart Rikk (2021); source, CC0. Observe the large cell bodies and branching dendrites; axons are not reliably identifiable here.
Medical illustration of a multipolar neuron by BruceBlaus. Source, CC BY 3.0. An explanatory rendering, not microscopy. Myelin is not shown. "Telodendria" means terminal axonal branches.
Transmission electron micrograph of a myelinated axon, Electron Microscopy Facility, Trinity College / Roadnottaken. Source, CC BY-SA 3.0. The original 500 nm scale bar is retained. The dark concentric lamellae are myelin.
Surface data: fsaverage5 left and right pial surfaces, from the Nilearn 0.10.4 dataset distribution. Reference: Fischl B, Sereno MI, Tootell RBH, Dale AM. High-resolution intersubject averaging and a coordinate system for the cortical surface. Human Brain Mapping. 1999;8(4):272-284. See the linked Nilearn documentation. Geometry is reoriented and normalized for display; no synthetic folds or lobe boundaries are added.
Renderer: this page uses an included JavaScript triangle renderer with a depth buffer and interpolated surface lighting. It does not depend on Three.js, WebGL, a point cloud, a remote viewer iframe, or an external JavaScript library. Model data and images are separate downloadable assets until an offline copy is saved. External resource links always require a connection.
Data redistribution notice (Nilearn BSD)
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