Ventricles of the Brain
- CSF is present inside the ventricles.
- CSF is formed by the choroid plexus in the lateral ventricles.
Ventricles | Embryological Origin |
Lateral ventricle | In telencephalon |
3rd ventricle | In diencephalon |
4th ventricle | In rhombencephalon |
NOTE: Encephalon
Primary Vesicle | Secondary Vesicle | Cavity | Adult Derivatives |
Prosencephalon (Forebrain) | Telencephalon | Lateral ventricles | • Cerebral cortex; • Subcortical white matter; • Amygdala; • Basal ganglia; • Hippocampus; • Olfactory bulb and tract |
ㅤ | Diencephalon | 3rd ventricle | • Thalamus; • Hypothalamus; • Epithalamus; • Subthalamus; • Optic nerve and retina |
Mesencephalon (Midbrain) | Mesencephalon | Cerebral aqueduct | • Midbrain |
Rhombencephalon (Hindbrain) | Metencephalon | 4th ventricle | • Pons; • Cerebellum |
ㅤ | Myelencephalon | 4th ventricle | • Medulla oblongata |
Flow of CSF
- Lateral ventricle → Foramen of Monro → 3rd ventricle → Aqueduct of Sylvius → 4th ventricle → 2 Foramen of Luschka (laterally), 1 Foramen of Magendie (medially) → Central canal of spinal cord.
- CSF goes out to the subarachnoid space.
- CSF is drained by arachnoid granulation.
- Finally drained by Dural venous sinuses.
- Majority of CSF goes to the superior sagittal sinus.
Aqueductal Stenosis
- Most common cause of congenital hydrocephalus
- Block in aqueduct of Sylvius or cerebral aqueduct.
- Leads to dilation of the 3rd ventricle.
- Primary cause of ventriculomegaly in newborn
Dandy-Walker Syndrome
- Atresia of foramina of Luschka and Magendie.
- Leads to dilation of the 4th ventricle.
- Mnemonic: Daddy Walk nu kondu poi → 4th classil
Treatment of hydrocephalus:
- Acetazolamide
- VP shunt (ventrico-peritoneal shunt)
- IOC for shunt infection→ shunt TAP
- Medical management:
- Mannitol
- 3% saline/ hypertonic saline
- glycerol
Sagittal section: 3rd and 4th Ventricle
3rd Ventricle
Anterior Wall
- Anterior commissure
- Lamina terminalis
Posterior Wall
- Pineal gland – below splenium
- Posterior commissure – below pineal gland
- Habenular commissure – above pineal gland
- Aqueduct of Sylvius
Floor
- Optic chiasma
- Infundibulum – between two optic tracts
- Tuber cinereum
- Mammillary body
- Posterior perforated substance
- Tegmentum
Lateral Wall
- Thalamus
- Hypothalamus
Roof
- Formed by Choroid plexus
- Fornix
Important Information
Structures | Location |
Tectum | Behind aqueduct of Sylvius |
Tegmentum | In front of aqueduct of Sylvius |
Lamina Terminalis
- Definition: Remnant of cranial neuropore
- Circumventricular Organ: No Blood-Brain Barrier (BBB).
Parinaud Syndrome
- Cause
- Pineal gland tumor
- Compress Dorsal midbrain → tectum and colliculi
- Damage to posterior commisure
- Supranuclead vertical gaze disorder
- Loss of upgaze
- Convergence divergence nystagmus on attempted upgaze
- Collier sign - Lid retraction
- Downward occular deviation: Setting sun sign
- Pseudo-Argyll–Robertson pupil
- Accommodative paresis
- Mid-dilated pupils
- Light–near dissociation (Light accomodation dissociation)
Lamina of Pineal Gland
Part of Pineal Stalk | Commissure Present |
Superior lamina | Habenular commissure |
Inferior lamina | Posterior commissure |
4th Ventricle
Lateral boundaries:
- SCP – Superior Cerebellar Peduncle
- ICP – Inferior Cerebellar Peduncle
- Gracile Tubercle
- Cuneate Tubercle
Floor
- Formed by the posterior surface of the pons and upper medulla.
- Elevations in the floor of the fourth ventricle:
- Rhomboid fossa
Roof
- Composed of:
- Superior Medullary Velum – white matter
- Inferior Medullary Velum – non-nervous structure
- Posterior Recess of 4th Ventricle
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