Fluid space · one in each half of the brain
Lateral ventricles
Also called First and second ventricles
Two big C-shaped fluid chambers, one curling through each half of the brain.
The lateral ventricles are the largest of the brain's fluid chambers, one in each hemisphere. Each is shaped like a big letter C that curls from the front of the brain toward the back, then down and forward into the temporal lobe. Most of the brain's cerebrospinal fluid is made inside them. The fluid then drains through small openings into the third ventricle.
Where it is
Inside each cerebral hemisphere, just under the corpus callosum. The caudate nucleus hugs the outside of its curve, the thalamus lies under its middle part, and the hippocampus forms part of the floor of its lower horn in the temporal lobe.
What it does
Making fluid
The choroid plexus inside them produces most of the brain's cerebrospinal fluid.
Holding fluid
They are the largest fluid reservoirs inside the brain.
Draining downward
Fluid leaves each one through a small opening, the interventricular foramen, into the third ventricle.
A guide on scans
Their size and shape are easy to see on brain scans, giving doctors clues about swelling or shrinking of the brain.
Think of them as a pair of curled ram's horns tucked inside the brain, filled with clear, flowing fluid.
Works with
- Choroid plexusThe choroid plexus runs along their floor and makes the fluid that fills them.
- Third ventricleThey drain into the third ventricle through two small openings, one on each side.
- Caudate nucleusThe caudate nucleus curves along their outer wall, following the same C-shape.
- HippocampusThe hippocampus bulges into the floor of their lower horn, deep in the temporal lobe.
- Corpus callosumThe corpus callosum forms their roof, arching over both of them.
- ThalamusThe thalamus lies beneath their central part.
When it goes wrong
Enlarged ventricles
They swell when fluid cannot drain properly (hydrocephalus). They also get bigger when the surrounding brain tissue shrinks, as happens with aging and in Alzheimer's disease.
A clue in schizophrenia
On average, people with schizophrenia have larger lateral ventricles than people without it. Whether this is a cause or a result of the illness is still being studied.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- Their C-shape comes from how the brain grows before birth: each hemisphere expands in a big curling arc, and the ventricle, caudate nucleus, fornix and hippocampus all follow that curve.
- It is normal for the left and right lateral ventricles to be slightly different sizes in healthy people.
Where the name comes from
"Lateral" means "to the side", since there is one on each side. They were historically counted as the first and second ventricles, which is why the next chamber down is called the third.
Learn it in a lesson
- Wiring and fluidWhite matter cables and the ventricles. A short guided lesson in 3D.
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the lateral ventricles?
Show the answer
Making fluid. The choroid plexus inside them produces most of the brain's cerebrospinal fluid.
Making fluid. The choroid plexus inside them produces most of the brain's cerebrospinal fluid.
The lateral ventricles is part of which larger structure?
Show the answer
Ventricular system. It belongs to the ventricular system.
Ventricular system. It belongs to the ventricular system.
Which part fits this description? "Like a pair of curled ram's horns tucked inside the brain, filled with clear, flowing fluid."
Show the answer
Lateral ventricles. It is the lateral ventricles. Two big C-shaped fluid chambers, one curling through each half of the brain.
Lateral ventricles. It is the lateral ventricles. Two big C-shaped fluid chambers, one curling through each half of the brain.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- Neuroanatomy, Ventricular System, StatPearls, NCBI Bookshelf
- Lateral ventricle, Radiopaedia
- 13.3 Circulation and the Central Nervous System, OpenStax, Anatomy and Physiology 2e
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Explore the lateral ventricles in 3D
Turn it around, zoom inside and see how it connects to the rest of the brain, then test yourself with quick quizzes.
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