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ANATOMY OF THE CEREBRAL VENTRICLES Francois du Toit Diagnostic Radiology Kimberley Hospital The Cerebral Ventricles Fluid filled (CSF) spaces within the brain 2 Lateral ventricles in each hemisphere 3rd ventricle, Cerebral Aquaduct, 4th ventricle midline Ependyma (thin epithelial membrane lining) The Cerebral Ventricles THE LATERAL VENTRICLE The Lateral Ventricles • Lies within each cerebral hemisphere: • Frontal Horn (anterior) • Body (atrium) • Temporal Horn (inferior) • Occipital Horn (posterior) • Interventricular Foramen (of Monroe) • connects each lateral ventricle with the 3rd ventricle • at junction of anterior horn & body The Lateral Ventricles The Lateral Ventricles THE LATERAL VENTRICLE FRONTAL HORN Frontal (anterior) Horn Extends into frontal lobe Roof & Ant extremity formed by: Corpus Collosum (Rostrum & Genu) Tapetum Floor & Lateral Wall Caudate Nucleus Medial Wall Septum Pellucidum Roof / Anterior Border Roof / Anterior Border Frontal (anterior) Horn Extends into frontal lobe Roof & Ant extremity formed by: Corpus Collosum (Rostrum & Genu) Tapetum Floor & Lateral Wall Caudate Nucleus Medial Wall Septum Pellucidum Floor of Anterior Horn Floor of Anterior Horn Frontal (anterior) Horn Extends into frontal lobe Roof & Ant extremity formed by: Corpus Collosum (Rostrum & Genu) Tapetum Floor & Lateral Wall Caudate Nucleus Medial Wall Septum Pellucidum Medial Wall of Anterior Horn THE LATERAL VENTRICLE BODY (atrium) Body of Lateral Ventricle In Parietal Lobe Roof & Lateral Wall Medial wall Thalamus Floor (lateral) Septum Pellucidum Floor (medial) Corpus Callosum Tapetal Fibres Body of Caudate Nucleus Thalamostriate vein in between Body of Fornix lies above the thalamus Between the fornix and the thalamus Choroid plexus lies invaginated into the cavity of the ventricle in a groove - the choroidal fissure Roof / Anterior Border Body of Lateral Ventricle In Parietal Lobe Roof & Lat Medial wall Thalamus Floor (lateral) Septum Pellucidum Floor (medial) Corpus Callosum Tapetal Fibres Body of Caudate Nucleus Thalamostriate vein in between Body of Fornix lies above the thalamus Between the fornix and the thalamus Choroid plexus lies invaginated into the cavity of the ventricle in a groove - the choroidal fissure Body of Lateral Ventricle In Parietal Lobe Roof & Lat Medial wall Thalamus Floor (lateral) Septum Pellucidum Floor (medial) Corpus Callosum Tapetal Fibres Body of Caudate Nucleus Thalamostriate vein in between Body of Fornix lies above the thalamus Between the fornix and the thalamus Choroid plexus lies invaginated into the cavity of the ventricle in a groove - the choroidal fissure Body of Lateral Ventricle Caudate Nucleus Thalamus The Lateral Ventricles Body of Lateral Ventricle In Parietal Lobe Roof & Lat Medial wall Thalamus Floor (lateral) Septum Pellucidum Floor (medial) Corpus Callosum Tapetal Fibres Body of Caudate Nucleus Thalamostriate vein in between Body of Fornix lies above the thalamus Between the fornix and the thalamus Choroid plexus lies invaginated into the cavity of the ventricle in a groove - the choroidal fissure The Lateral Ventricles Body of Fornix Choroid Plexus Thalamus THE LATERAL VENTRICLE TEMPORAL HORN (inferior) Temporal (inferior) Horn Extends anteriorly into Temporal Lobe Lateral wall Roof Fibres of Tapetum Tail of Caudate Nucleus Floor Hippocampus pes hippocampi anterior crus of the fornix arising from this Tapetum Temporal Horn of Lateral Ventricle Temporal (inferior) Horn Extends anteriorly into Temporal Lobe Lateral wall Roof Fibres of Tapetum Tail of Caudate Nucleus Floor Hippocampus pes hippocampi anterior crus of the fornix arising from this Temporal (inferior) Horn Extends anteriorly into Temporal Lobe Lateral wall Roof Fibres of Tapetum Tail of Caudate Nucleus Floor Hippocampus pes hippocampi anterior crus of the fornix arising from this Crus of Fornix Hippocampus Pes THE LATERAL VENTRICLE OCCIPITAL HORN (Posterior) Occipital (posterior) Horn Posterior Extension of Lateral ventricle Extends into Occipital Lobe Arises from trigone of lateral ventricle posterior convexity of the body of the lateral ventricle May be absent / poorly developed / extend the full depth 12% bilaterally well developed THE CHOROID PLEXUS Choroid Plexus of Lateral Ventricle Responsible for most of the production of CSF Extends from Inferior horn, through body, to interventricular foramen NO CHOROID PLEXUS in Occipital & Frontal Horn Continuous with Choroid Plexus of 3rd ventricle Invaginated into Lateral Ventricles medially (Choroidal Fissure) Choroid Plexus of Lateral Ventricle Choroid Plexus of Lateral Ventricle Blood supply: Ant Choroidal a. (Branch of ICA) Post Choroidal a. (Branch of post Cerebral a.) Venous drainage: Sup Choroidal vein (begins at inferior horn and passes anteriorly to IV foramen) Joins Sup Thalamostriate v. to form Internal Cerebral vein at IV foramen rd 3 Ventricle Slit-like space between Thalami Width = 2-10mm (increasing with age) Thin anterior wall – Lamina Terminalis between ant commissure (above) to optic chiasm (below) Extension inferiorly into optic chiasm = supraoptic recess Floor = Structures of hypothalamus including pituitary whose hollow stalk is the infundibular recess of the ventricle Fold of Pia containing CP = Tela Choroidea Narrow Anterior Apex at IV Foramen Wider Posterior If Fluid accumulates = Cavum Velum Interpositum Thalamus Third Ventricle rd 3 Ventricle Slit-like space between Thalami Width = 2-10mm (increasing with age) Thin anterior wall – Lamina Terminalis between ant commissure (above) to optic chiasm (below) Extension inferiorly into optic chiasm = supraoptic recess Floor = Structures of hypothalamus including pituitary whose hollow stalk is the infundibular recess of the ventricle Fold of Pia containing CP = Tela Choroidea Narrow Anterior Apex at IV Foramen Wider Posterior If Fluid accumulates = Cavum Velum Interpositum Anterior Commisure Lamina Terminalis Optic Chiasm rd 3 Ventricle Slit-like space between Thalami Width = 2-10mm (increasing with age) Thin anterior wall – Lamina Terminalis between ant commissure (above) to optic chiasm (below) Extension inferiorly into optic chiasm = supraoptic recess Floor = Structures of hypothalamus including pituitary whose hollow stalk is the infundibular recess of the ventricle Fold of Pia containing CP = Tela Choroidea Narrow Anterior Apex at IV Foramen Wider Posterior If Fluid accumulates = Cavum Velum Interpositum rd 3 Ventricle Slit-like space between Thalami Width = 2-10mm (increasing with age) Thin anterior wall – Lamina Terminalis between ant commissure (above) to optic chiasm (below) Extension inferiorly into optic chiasm = supraoptic recess Floor = Structures of hypothalamus including pituitary whose hollow stalk is the infundibular recess of the ventricle Fold of Pia containing CP = Tela Choroidea Narrow Anterior Apex at IV Foramen Wider Posterior If Fluid accumulates = Cavum Velum Interpositum rd 3 Ventricle Slit-like space between Thalami Width = 2-10mm (increasing with age) Thin anterior wall – Lamina Terminalis between ant commissure (above) to optic chiasm (below) Extension inferiorly into optic chiasm = supraoptic recess Floor = Structures of hypothalamus including pituitary whose hollow stalk is the infundibular recess of the ventricle Fold of Pia containing CP = Tela Choroidea Narrow Anterior Apex at IV Foramen Wider Posterior If Fluid accumulates = Cavum Velum Interpositum Cavum Velum Interpositum rd 3 Ventricle Posteriorly - extends as small pineal recess into pineal stalk, and above this into suprapineal recess Roof - anteriorly, the anterior commissure, column of fornix and IV foramen. Behind this the body of the fornix, with Choroid plexus invaginating below the fornix 60% of people - thalami connected across the ventricle via massa intermedia (non-neural connection) rd 3 Ventricle Posteriorly - extends as small pineal recess into pineal stalk, and above this into suprapineal recess Roof - anteriorly, the anterior commissure, column of fornix and IV foramen. Behind this the body of the fornix, with Choroid plexus invaginating below the fornix 60% of people - thalami connected across the ventricle via massa intermedia (non-neural connection) Fornix Choroid Plexus Ant Commisure rd 3 Ventricle Posteriorly - extends as small pineal recess into pineal stalk, and above this into suprapineal recess Roof - anteriorly, the anterior commissure, column of fornix and IV foramen. Behind this the body of the fornix, with Choroid plexus invaginating below the fornix 60% of people - thalami connected across the ventricle via massa intermedia (non-neural connection) THE CEREBRAL AQUEDUCT Cerebral Aquaduct Narrow channel connecting post end of 3rd ventricle with sup end of 4th ventricle 1.5cm in length. 1-2mm in diameter Passes through Brainstem with Tectum posterior to it and Tegmentum and Cerebral Peduncles anteriorly Nuclei of CN III,IV,V surround aqueduct and are called the periaqueductal grey matter Cerebral Aqueduct th 4 Ventricle Aqueduct widens Posterior to the Pons Narrows again in inferior part of medulla as central canal of the medulla & of spinal cord Floor = diamond shaped (rhomboid fossa) Formed by post surface of pons and upper part of medulla Roof SUPERIOR superior cerebellar peduncle with sup medullary velum between INFERIOR inf cerebellar peduncle and the inf medullary velum Over these lies the cerebellum th 4 Ventricle th 4 Ventricle th 4 Ventricle Aqueduct widens Posterior to the Pons Narrows again in inferior part of medulla as central canal of the medulla & of spinal cord Floor = diamond shaped (rhomboid fossa) Formed by post surface of pons and upper part of medulla Roof SUPERIOR superior cerebellar peduncle with sup medullary velum between INFERIOR inf cerebellar peduncle and the inf medullary velum Over these lies the cerebellum th 4 Ventricle Roof th 4 Ventricle Foramina Foramina of th 4 Ventricle 3 Openings in lower part of roof one median aperture (of Magendie) large opening in inf medullary velum beneath the cerebellum, which communicates with the cisterna magna two lateral apertures (of Luschka) at apex of lateral recesses of the ventricle open anteriorly just behind CN VIII into the pontine cistern Choroid plexus invaginates the lower part of its roof and is supplied by inferior cerebellar a. Foramen of Magendie 4th Ventricle Foramina 3 Openings in lower part of roof one median aperture (of Magendie) large opening in inf medullary velum beneath the cerebellum, which communicates with the cisterna magna two lateral apertures (of Luschka) at apex of lateral recesses of the ventricle open anteriorly just behind CN VIII into the pontine cistern Choroid plexus invaginates the lower part of its roof and is supplied by inferior cerebellar a. Foramen of Luschka 4th Ventricle Foramina 3 Openings in lower part of roof one median aperture (of Magendie) large opening in inf medullary velum beneath the cerebellum, which communicates with the cisterna magna two lateral apertures (of Luschka) at apex of lateral recesses of the ventricle open anteriorly just behind CN VIII into the pontine cistern Choroid plexus invaginates the lower part of its roof and is supplied by inferior cerebellar a. Choroid Plexus of th 4 Ventricle CSF PRODUCTION & FLOW CSF Production & Flow Total Volume of CSF = 150ml (25ml is within and around the spinal cord) Produced at 0.4ml/min Production independent of CSF pressure Principally produced by Choroid Plexus of lateral ventricles CSF Flow Flows through Interventricular foramen into 3rd ventricle Via Cerebral Aqueduct to 4th Ventricle Via Midline Aperture (of Magendie) into Cisterna Magna Via Lateral Apertures into Pontine Cistern From Basal Cisterns some fluid flows down and bathes the spinal cord The Remainder passes upward through tentorial hiatus and diffuses over surface of the cerebral hemispheres CSF Flow Into rd 3 Ventricle (Monroe) Into th 4 Venticle (Cerebral Aqueduct) Into Cisterna Magna (Magendie) Down to Spinal Cord Upwards over Cerebral Hemispheres CSF Absorbtion CSF is absorbed through the Arachnoid Villi herniations of arachnoid through holes in the dura into venous sinuses most numerous in sup sagittal sinus discrete in children with age they aggregate into visible clumps called arachnoid granulations these indent the inner table of the skull beside the dural venous sinuses Arachnoid Villi CSF Absorbtion 1/3 CSF absorbed along similar spinal villi OR escapes along nerve sheaths into perineural lymphatics This absorption is passive and dependent on hydrostatic pressure differences ANATOMICAL VARIANTS Cavum Velum Interpositum Fluid Collects in Tela Choroidea Narrow apex anterior Wider Posteriorly Cavum Velum Interpositum Cavum Septum Pellucidum Two potential spaces between leaflets of Septum Pellucidum ANTERIOR Cavum Septum Pellucidum POSTERIOR Cavum Vergae Obliterate Postero-anteriorly during development CSP present in 100% of fetusses 85% Obliterate by 3-6months Absent CSP in fetus associated with significant CNS abnormalities Cavum Vergae Seperation of the leaflets of septum pellucidum Posterior extension to the splenium of corpus collosum Because of ordered obliteration – CSP almost always accompanies a Cavum Vergae Cavum Vergae Cavum Septum Pellucidu m Cavum Vergae References Anatomy for Diagnostic Imaging, rd 3 Stephanie Ryan, Michelle McNicholas, Stephen Eustace Atlas of Human Anatomy, 2nd Edition Frank H. Netter http://www.imaios.com/ http://www.radiopaedia.org/ Edition