Ventricles & CSF cisterns

1. Ventricles & CSF cisterns

2. Ventricles • CSF filled spaces in the brain related to development of the nervous system as a tubular structure with central canal • Lined with ependyma • Plexuses of highly vascular pia mater form choroid plexuses which produce CSF

3. Lateral Ventricles • C-shaped facing anteriorly • Occupy each cerebral hemisphere • Communicates with 3rd ventricle at junction of anterior horn and body – interventricular foramen (of Monro)

4. Lateral Ventricles • Anterior horn – within frontal lobe • Anterior: genu corpus callosum • Roof: body corpus callosum • Medial: septum pellucidum • Floor/lateral wall: head of caudate nucleus • Body – within parietal lobe • Roof: body corpus callosum • Medial: septum pellucidum • Lateral wall: body of caudate nucleus • Floor: thalamus (medially)

5. Lateral Ventricles • Temporal (inferior) horn • Roof: tail of caudate nucleus • Floor: hippocampus • Lateral: tapetum (fibres of corpus callosum) • Anterior: amygdaloid nucleus • Occipital horn (posterior) • Extends from posterior convexity of the “C” – trigone • Lateral: tapetum & optic radiation • Medial: white matter indented by grey matter of calcarine sulcus (calcar avis)

6. Choroid plexus • Composed of invaginated highly vascular pia called tela choroidea • Extends from inferior horn, body into intraventricular foramen and continuous in 3rd ventricle. 4th ventricle also contains a chorioid plexus. • Blood supply • Anterior choroidal (br internal carotid) enters anterior part of temporal horn • Posterior choroidal (br PCA) enters body of lateral ventricle above the thalamus • Venous drainage • Choroidal v in inferior horn, passing anteriorly to intraventricular foramen, joins with thalamostriate v to form internal cerebral v

7. Third ventricle • Slit like space between the thalami • Thin anterior wall (lamina terminalis) from anterior commissure superiorly to optic chiasm inferiorly • Inferiorly extension into optic chiasm (supraoptic recess) and infundibulum (infundibular recess) • Posterior extension into pineal stalk (pineal recess) and suprapineal recess above this

8. Third ventricle • Anterior: anterior commissure • Roof: anterior commissure, intraventricular foramen, body of the fornix • Floor: structures of hypothalamus incl. pituitary • Lateral: thalami • Thalami are connected across the ventricle in 60% of people by a non-neural connection – massa intermedia

9. Cerebral Aqueduct • Narrow channel passing through brainstem connects posterior end of 3rd ventricle and superior end of 4th ventricle • 1.5cm length, 1-2mm diameter • Anterior: cerebral peduncles & tegmentum • Posterior: tectum • Nuclei of CN III, IV, V surround aqueduct

10. Fourth ventricle • Extends as a widening of the aqeduct posterior to the pons to the obex (caudal tip of the fourth ventricle; a marker for the level of the foramen magnum of the skull) • Floor: rhomboid fossa (pons and upper part of medulla) • Roof: cerebellum (superior and inferior medullary vela) • Lateral: cerebellar peduncles • Communicates with the subarachnoid space through • Median aperture (foramen of Magendie) in the inferior medullary vellum open into the cerebellomedullary cistern (cisterna magna) • two lateral foramina of Luschka in the lateral recesses open anteriorly into the pontine cistern

11. Cisterns • Collections of deep CSF spaces around the brain • Cerebellomedullary cystern • posterior to medulla and inferior to cerebellar hemispheres • Receives CSF from 4th ventricle via median aperture • Continues as spinal subarachnoid space through foramen magnum • Contents: vertebral a and posterior inferior cerebellar branch • Pontine cistern • Between pons and clivus • Cerebellomedullary cystern above, Interpenduncular cistern below • Contents: basilar artery and assoc branches • Interpenduncular cistern