Four connected cavities in the brain filled with clear fluid
Cerebral ventricles — two lateral, a third and a fourth.
Anatomy · Brain & nerves
Cerebral ventricles
Four fluid-filled chambers
Brain · cerebrospinal fluid system
A connected system of four cavities deep in the brain filled with cerebrospinal fluid: two C-shaped lateral ventricles, one in each hemisphere, the slit-like third ventricle between the two halves of the thalamus, and the diamond-shaped fourth ventricle in front of the cerebellum. The choroid plexus in their walls makes the fluid, which drains out into the subarachnoid space around the brain and cord.
How to spot them
- ▸Two curved 'horns' in each hemisphere, like butterfly wings in a horizontal or coronal slice
- ▸A narrow midline slit between the two halves of the thalamus
- ▸A diamond-shaped space behind the pons and medulla, under the cerebellum, leading down to the spinal canal
- ▸Slender channels join them: the interventricular foramina and the cerebral aqueduct
What to know
Two C-shaped chambers, one in each cerebral hemisphere, with frontal, occipital and temporal horns
Cerebral ventricles — the lateral ventricles.
The fluid-making tufts of capillaries in their walls produce about half a litre a day
Cerebral ventricles — the choroid plexus makes cerebrospinal fluid.
A narrow channel through the midbrain links the third and fourth chambers; blocking it swells the ones above
Cerebral ventricles — the cerebral aqueduct; obstruction causes hydrocephalus.
Two small holes link each lateral one to the slit between the thalami, named after an eighteenth-century Edinburgh professor of anatomy
Cerebral ventricles — the interventricular foramina of Monro, after Alexander Monro secundus.
Its floor is the diamond-shaped 'rhomboid fossa' behind the pons and medulla, with exits into the subarachnoid space
Cerebral ventricles — the fourth ventricle and its median and lateral apertures (Magendie and Luschka).
An excess of fluid enlarging them in babies makes the head grow abnormally large
Cerebral ventricles — hydrocephalus, 'water on the brain'.
A needle passed into the fluid space in the lower back samples the same fluid that fills them
Cerebral ventricles — cerebrospinal fluid in a lumbar puncture.
Key ideas
- Fluid flows lateral ventricles, then the third ventricle, then the fourth, and leaves into the subarachnoid space, where arachnoid granulations return it to the blood.
- The fluid is replaced three to four times a day; the ventricles themselves hold only roughly 25 mL of the 150 mL or so of CSF, the rest lying around the brain and cord.
Quick-fire facts
- •Four in all: two lateral, one third, one fourth
- •The lateral ventricles connect to the third through the interventricular foramina (of Monro)
- •The third and fourth ventricles are linked by the cerebral aqueduct (of Sylvius)
- •The fourth ventricle opens into the subarachnoid space via the median aperture (foramen of Magendie) and two lateral apertures (foramina of Luschka)
- •The choroid plexus produces roughly 500 mL of cerebrospinal fluid per day, turning over the roughly 150 mL total three or four times daily
- •The word 'ventricle' means 'little belly' in Latin; the heart's ventricles share the name
- •Hydrocephalus results from obstructed flow or impaired absorption, and is treated with a shunt
- •The fluid is absorbed through arachnoid granulations into the dural venous sinuses
- •Each lateral ventricle has a body and frontal, occipital and temporal horns
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Sources
- TeachMeAnatomy — Ventricles of the brain
- OpenStax — 13.3 Circulation and the Central Nervous System — Anatomy and Physiology 2e