Ventricles & CSF cisterns

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

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)

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 Lateral wall: body of caudate nucleus Floor: thalamus (medially)

Lateral Ventricles Temporal (inferior) horn Occipital horn (posterior) 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)

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

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

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

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

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

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