• Location: between the right and left thalami.
• Extends from the interventricular foramen (of Monro) anteriorly → to the cerebral aqueduct (of Sylvius)posteriorly.
Boundaries | Formed by |
Roof | • Choroid plexus • Fornix |
Floor | Formed by hypothalmic structure- • Optic chiasma • Infundibulum • Tuber cinereum • Mammillary bodies • Posterior perforated substance • Tegmentum of midbrain |
Lateral wall | • Thalamus (superior part) • Hypothalamus (inferior part) |
Anterior wall | Anterior commissure Lamina terminalis |
Posterior wall | • Pineal gland • Posterior commissure: Below pineal gland • Habenular commisure: Above pineal gland • Aqueduct of sylvius: b/w 3rd & 4th ventricle |
• Interventricular foramina (of Monro) → connect lateral ventricles to third ventricle.
• Cerebral aqueduct (of Sylvius) → connects third ventricle to fourth ventricle.
Tectum | Tegmentum | |
Posterior (dorsal) to the cerebral aqueduct | Location | Anterior (ventral) to the cerebral aqueduct |
– Superior colliculi (visual reflexes) – Inferior colliculi (auditory reflexes) | Main Structure | – Red nucleus – Substantia nigra (dorsal part) – Cranial nerve nuclei (III & IV) – Reticular formation – Ascending tracts |
Forms the dorsal roof of midbrain | Position | Forms the central core of midbrain (b/w tectum & crus cerebri) |
