The two lateral ventricles – one in each cerebral hemisphere are the largest of the ventricles. The third ventricle is a narrow midline cavity between the thalamus and hypothalamus. The fourth ventricle is positioned between the brainstem and cerebellum.1
References:
1. Shenoy SS, Lui F. Neuroanatomy, ventricular system. [Updated 2023 Jul]. In: StatPearls [internet]. Treasure Island (FL): StatPearls Publishing; 2023. Available at: https://www.ncbi.nlm.nih.gov/books/NBK532932/.
2. Javed K, Reddy V, Lui F. Neuroanatomy, choroid plexus. [Updated 2023 Jul]. In: StatPearls [internet]. Treasure Island (FL): StatPearls Publishing; 2023. Available at: https://www.ncbi.nlm.nih.gov/books/NBK538156/.
3. Bailey R. Ventricular system of the brain. ThoughtCo. Available at: https://www.thoughtco.com/ventricular-system-of-the-brain-3901496. Accessed December 1, 2025.