Third ventricle
Ventriculus tertius
NervousOrgansHead
- What it is
- A narrow vertical slit in the midline between the two thalami, floored by the hypothalamus; small recesses point toward the optic chiasm, the pituitary stalk and the pineal gland.
- Function
- Passes CSF from the lateral ventricles (via the foramina of Monro) back to the cerebral aqueduct.
- Size
- About 2-3 cm long, 2 cm high and only 3-5 mm wide
- Clinical note
- Its width on CT is a sensitive sign of hydrocephalus or brain atrophy; a colloid cyst at its roof can block both foramina of Monro suddenly.