02 Ventricles & CSF Route.pdf

Ventricles & CSF Route Prof Dara M Cannon VENTRICLES • Ventricles are cavities or spaces within the brain • Ventricles contain cerebrospinal fluid (CSF) which is produced by a vascular structure choroid plexus which lies inside the ventricles • There are a series of these spaces, one is bilateral...

Ventricles & CSF Route Prof Dara M Cannon VENTRICLES • Ventricles are cavities or spaces within the brain • Ventricles contain cerebrospinal fluid (CSF) which is produced by a vascular structure choroid plexus which lies inside the ventricles • There are a series of these spaces, one is bilateral (a pair with one in each hemisphere) and the others are singular structures along the midline with varying shapes/dimensions Objectives • Know and track the route of CSF from formation at the choroid plexuses to the end when it reaches the venous sinuses • Understand each ventricle in relation to its’ development, boundary brain structures and the CSF route • • • • Neural Tube 3 primary brain vesicles 5 secondary brain vesicles Cavities develop into ventricles Development of the Ventricles CHOROID PLEXUS • Ventricles contain cerebrospinal fluid (CSF) formed by choroid plexus • Ventricles are lined by ependymal cells which specialise to form choroid plexus • Choroid plexus receives an arterial blood supply from the choroidal arteries • Using arterial blood supplied choroid synthesizes CSF, a clear fluid that fills the ventricles first and then proceeds to flow to fill a layer surrounding the brain and spinal cord (see meninges lecture) LATERAL VENTRICLES • Paired spaces, one in each hemisphere • Extend through each lobe of the cerebrum • The interventricular foramen THIRD VENTRICLE • A single unpaired midline space in the diencephalon • CSF flows from the lateral ventricles (#2) through the interventricular foramen (#2) into the third ventricle (#1) THE CEREBRAL AQUEDUCT • A narrow canal through the midbrain of the brainstem • CSF flows from the third ventricle into the cerebral aqueduct FOURTH VENTRICLE • A singular space posterior to the brainstem and anterior to the cerebellum • CSF flows from the cerebral aqueduct into the fourth ventricle • CSF then leaves the ventricular system to one of two routes • Central canal of the spinal cord • Exit into the layer between the coverings (meninges) of the brain CHOROID PLEXUS LOCATIONS • The three core locations of choroid plexus are • the floor of the lateral ventricle • the roof of the third ventricle and • the fourth ventricle Ventricular System Overview – Lateral View • Lateral ventricles • Third ventricle • Cerebral Aqueduct • Fourth ventricle • Central canal Ventricular System Overview – Anterior View Longitudinal fissure LATERAL VENTRICLES INTERVENTRICULAR FORAMEN THIRD VENTRICLE AQUEDUCT OF THE MIDBRAIN Pons FOURTH VENTRICLE LATERAL APERTURE MEDIAN APERTURE Medulla oblongata Spinal cord CENTRAL CANAL (b) Anterior view of brain • Lateral ventricle • Interventricular foramen • Foramen of Monroe • Third ventricle • Cerebral aqueduct • Fourth ventricle • Median Aperture to Central Canal • Lateral apertures to the subarachnoid space • Cisterns • • • • Pool of CSF in subarachnoid space Quadrigeminal cistern between the posterior corpus callosum and the cerebellum (recall tentorial notch) Cisterna magna at the foramen magnum Arachnoid Villi/Granules to Venous sinus Summary of CSF Route Hydrocephalus • Overproduction of CSF, failure to drain or obstruction of flow • Dilates the ventricles • Separates the calvaria in infants • Hydrocephalus occurs with congenital abnormalities, head injury, meningitis, and episodes of bleeding into the brain (rupture of pia) • Image: Aqueductal Stenosis Ventricles on MR Images Study Aid • Use E-anatomy to scroll through these slices: go to E-anatomy, choose MRI Brain, scroll through axial slices, alter settings under ‘anatomical structures’ to show only ventricles labels ( do the same choosing only ‘meninges’ after that lecture), • Watching changes as you scroll gives you a 3D sense of the shape of the structures and spaces • Test your knowledge by attempt to locate and identify them using Quiz mode • Complete this prior to the relevant practical Question to Aid your Revision • Ventricles • Can you name the three main locations of formation of CSF precisely and the cell type involved? • Can you name the spaces in order of the route of flow of CSF through to the end? • For each ventricle what brain area is it associated with (cerebrum, diencephalon, midbrain?) • Do you know the anatomical relations of each space, could you readily identify each ventricle on an MRI in any orientation? (Use E-anatomy for this one and start with just the lateral ventricles for example, see book Table 5.1 p132) POSTERIOR ANTERIOR Superior cerebral vein CHOROID PLEXUS OF LATERAL VENTRICLE ARACHNOID VILLUS CHOROID PLEXUS OF THIRD VENTRICLE SUPERIOR SAGITTAL SINUS SUBARACHNOID SPACE Cerebrum Corpus callosum Intermediate mass of thalamus LATERAL VENTRICLE Posterior commissure INTERVENTRICULAR FORAMEN Anterior commissure Great cerebral vein THIRD VENTRICLE Straight sinus Midbrain Pons LATERAL APERTURE AQUEDUCT OF THE MIDBRAIN (CEREBRAL AQUEDUCT) Cerebellum CHOROID PLEXUS OF FOURTH VENTRICLE Hypothalamus Cranial meninges: Pia mater FOURTH VENTRICLE Arachnoid mater Medulla oblongata Dura mater Spinal cord MEDIAN APERTURE CENTRAL CANAL Sagittal plane SUBARACHNOID SPACE View Filum terminale (b) Sagittal section of brain and spinal cord Path of: CSF Venous blood Superior sagittal sinus ARACHNOID VILLUS LATERAL VENTRICLE Falx cerebri CHOROID PLEXUS Corpus callosum Cerebrum Septum pellucidum AQUEDUCT OF THE MIDBRAIN (CEREBRAL AQUEDUCT) THIRD VENTRICLE SUBARACHNOID SPACE (surrounding brain) Cerebellum Tentorium cerebelli LATERAL APERTURE FOURTH VENTRICLE MEDIAN APERTURE Frontal plane SPINAL CORD SUBARACHNOID SPACE (surrounding spinal cord) (c) Frontal section of brain and spinal cord View Cranial Bones DR PREP & ACTIVITY GUIDE Goal: locating the major landmarks, identifying specific key features and increasing your naming fluency and presicsion of identification of the location of features in question on gross specimens and radiological images ❑ ❑ ❑ ❑ ❑ ❑ Skull Base ❑ ❑ ❑ ❑ ❑ ❑ Frontal bone 2 parietal bones Occipital bone 2 temporal bones Sphenoid Ethmoid Foramen magnum Carotid foramen Jugular foramen Anterior cranial fossa Middle cranial fossa Posterior cranial fossa Lateral Cerebrum ❑ Bones: using skull cap and base note the cranial fossa, key foramen and sutures as dividing marks between bones ❑ ❑ ❑ ❑ ❑ Lateral/Sylvian Fissure Central Sulcus Frontal Gyri F1, F2, F3 Temporal Gyri: T1, T2, T3 F3 - Inferior Frontal G&S ❑ ❑ ❑ ❑ ❑ pars orbitalis Pars triangularis Pars opercularis Subcentral gyrus Broca’s area – speech ❑ Angular Gyrus ❑ Lateral Cerebrum: locate the lateral/sylvian fissure and the central sulcus, name gyri and sulci ❑ ❑ ❑ ❑ ❑ GROSS SPECIMENS ❑ Medial Cerebrum: locate main structures, identify each ventricle space, name key gyri/sulci ❑ Inferior Cerebrum: locate major landmarks first - orbital surface, temporal pole, olfactory and optic nerves, name key gyri/sulci 3D MODEL, SAGITTAL MR & SAGITTAL GROSS SPECIMEN ❑ Use the ventricle model to revise the route and locate ventricle each on a sagittal brain Longitudinal fissure Precentral gyrus Postcentral gyrus Frontal & Temporal Poles Intraparietal Sulcus ❑ Supramarginal Gyrus ❑ Insular Gyri ❑ 3 insular short gyri – ant, mid, post ❑ 2 insular long gyri – sup, inf Medial Cerebrum & Ventricles ❑ ❑ ❑ ❑ ❑ ❑ ❑ Corpus callosum Diencephalon - Thalamus Cingulate cortex & bundle Midbrain, Pons & Medulla Cerebellum Superior and Medial frontal G Caudate Nucleus ❑ ❑ ❑ ❑ ❑ ❑ ❑ Lateral ventricle & choroid Interventricular foramen Third ventricle & choroid Cerebral aqueduct Fourth ventricle, central canal Parahippocampal Gyrus (PHG) Subarachnoid cisterns Inferior Cerebrum & Base features ❑ ❑ ❑ ❑ ❑ Olfactory nerve and trigone Gyrus rectus Orbital Gyri Optic nerve, chiasm, tract Pituitary, mammillary bodies ❑ ❑ ❑ ❑ ❑ T3 & O3 inferior T/O gyri Occipitotemporal sulcus T4-O4-LOTG, fusiform Collateral sulcus T5 PHG, O5-MOTG/lingual