Ventricula System PDF - Neuroanatomy Lecture Notes

VENT RICULAR SYSTEM Prepared by: Marilou A. Contreras, PTRP, MSCPD, EdD COPYRIGHT NOTICE  TOPIC OUTLINE 1. Ventricular system 2. Cerebrospinal fluid (CSF) 3. Clinical correlation VENTRICULAR SYSTEM  Ventricular systems 2 SYSTEMS: 1. INTERNAL SYSTEM a. 2 latera...

VENT RICULAR SYSTEM Prepared by: Marilou A. Contreras, PTRP, MSCPD, EdD COPYRIGHT NOTICE  TOPIC OUTLINE 1. Ventricular system 2. Cerebrospinal fluid (CSF) 3. Clinical correlation VENTRICULAR SYSTEM  Ventricular systems 2 SYSTEMS: 1. INTERNAL SYSTEM a. 2 lateral ventricles b. Interventricular foramina / foramina of Monro c. Third ventricle d. Cerebral aqueduct/ aqueduct of Sylvius e. Fourth ventricle f. Central canal 2. EXTERNAL SYSTEM a. Subarachnoid spaces and cisterns Ventricular systems  Ventricles Four-filled cavities located within the brain: 1. 2 Lateral ventricles 2. Third ventricle 3. Fourth ventricle Lined with ependyma Filled with cerebrospinal fluid (CSF)  Ventricular systems Communication between the internal & external systems: 3 FORAMINA IN THE FOURTH VENTRICLE a. Foramen of Magendie 1 midline aperture b. Foramina of Luschka 2 lateral apertures  Foramina of the ventricular system 1. (2) Interventricular foramina / Foramina of Monro 2. (1) Cerebral aqueduct / Aqueduct of Sylvius) 3. (1) Foramen of Magendie 4. (2) Foramina of Luschka  Lateral ventricles 2 large, C-shaped ventricles, one in each cerebral hemisphere Possess: body, horns (anterior, posterior, inferior) Communicates with the third ventricle via interventricular (Monro) foramen  Interventricular (Monro) foramen Aperture between the column of the fornix and the anterior end of the thalamus Allow communication between lateral ventricles and the third ventricle  Third ventricle Slitlike cleft between the 2 thalami Communicates anteriorly with the lateral ventricles through the interventricular foramen (foramen of Monro) Communicates posteriorly with the Fourth ventricle through the cerebral aqueduct  Cerebral aqueduct AKA “Aqueduct of Sylvius” A narrow, curved channel running from the posterior third ventricle into the fourth ventricle It contains no choroid plexus  Fourth ventricle Tent-shaped cavity Lined with ependyma Located anterior to the cerebellum and posterior to pons and superior half of medulla oblongata Possesses 2 lateral boundaries, rhomboid- shaped floor and roof  Foramen of Magendie The median aperture An opening in the caudal portion of the roof of the ventricle Most of the outflow of CSF from the fourth ventricle passes through this aperture, which varies in size  Foramen of Luschka The lateral aperture The opening of the lateral recess into the subarachnoid space near the flocculus of the cerebellum A tuft of choroid plexus is commonly present in the aperture and partly obstructs the flow of CSF from the fourth ventricle to the subarachnoid space  Subarachnoid space Interval between the arachnoid mater and pia mater Receives CSF from the fourth ventricle via the foramina of Magendie and Luschka Filled with CSF and contains blood vessels Traversed by fine trabeculae (CT) Ends below at the level of S2-S3 vertebrae Extensions: perivascular space, subarachnoid cisterns (expansions)  Subarachnoid cisterns SUBARACHNOID LOCATION CISTERNS CISTERNA MAGNA / Occupies the interval CEREBELLO- between the cerebellum MEDULLARY and medulla CISTERN Receives CSF through the foramen of Magendie PONTINE CISTERN Basal cisterns beneath the brainstem and INTERPEDUNCULAR diencephalon CISTERN CISTERN OF THE OPTIC CHIASMA CISTERN OF THE Continuation of the LAMINA cistern of the optic TERMINALIS chiasma  Subarachnoid cisterns SUBARACHNOID LOCATION CISTERNS CISTERN OF Continuation of the cistern of CORPUS lamina terminalis CALLOSUM SUPERIOR CISTERN The subarachnoid space / CISTERN OF THE dorsal to the midbrain GREAT CEREBRAL VEIN CISTERNAL Formed by the cistern of the AMBIENS / PERI- great cerebral vein and the MESENCEPHALIC subarachnoid space on the CISTERN sides of the midbrain CISTERN OF THE Corresponds with lateral LATERAL SULCUS fissure LUMBAR CISTERN Extends from the L2 vertebra to the S2 Contains the cauda equina  Central canal of the medulla and spinal cord Opens superiorly into the fourth ventricle Extends inferiorly through the inferior medulla and throughout the spinal cord Terminal ventricle = expansion of the central canal in the conus medullaris Has no choroid plexus CEREBROSPINAL FLUID (CSF)  CEREBROSPINAL FLUID (CSF) Appearance: Clear, colorless fluid Total volume: 150 ml Rate of production: 0.5 ml / min Turnover time: 5 hours Cells: Lymphocytes Biomolecules: Glucose, protein, chloride Location: Subarachnoid, perivascular spaces central canal of medulla and SC  Functions of CSF 1. Cushions and protects the CNS from trauma 2. Provides mechanical buoyancy and support for the brain 3. Serves as a reservoir and assists in the regulation of the contents of the skull 4. Nourishes the CNS 5. Removes metabolites from the CNS 6. Serves as a pathway for pineal secretions to reach the pituitary gland  Formation of CSF CSF Production is not pressure-regulated 1. Choroid plexuses of lateral, third, and fourth ventricles = MAIN PRODUCER 2. Ependymal cells lining the ventricles 3. Brain substance through the perivascular spaces  Choroid plexus A fringe-like vascular process of pia mater Containing capillaries of the choroid arteries Covered by an epithelial layer of ependymal origin It projects into the ventricular cavity  Choroid plexus Location: 1. lateral ventricle (body and inferior horns) 2. Interventricular (Monro) foramen 3. third ventricle 4. fourth ventricle There is no choroid plexus in the anterior and posterior horns, cerebral aqueduct  Absorption of CSF Occurs when CSF pressure exceeds that of venous pressure in the sinus (arachnoid villi serves as valves) Controls CSF pressure 1. Arachnoid villi / arachnoid granulations into the venous dural sinuses (especially superior sagittal sinus) = MAIN SITE OF ABSORPTION 2. Veins in the subarachnoid space 3. Perineural lymph vessels of cranial and spinal nerves CSF CIRCULATION  CSF CIRCULATION FACILITATION OF SLOW FLOW OF CSF BY: 1. Pulsations of cerebral and spinal arteries 2. Movements of the vertebral column MIXING OF CSF FACILITATED BY: 1. Movements of vertebral column 2. Respiration 3. Coughing 4. Changing body positions CLINICAL CORRELATION NORMAL NON-COMMUNICATING COMMUNICATING HYDROCEPHALUS HYDROCEPHALUS  REFERENCES: Splittgerber, R. (2019). Snell’s Clinical Neuroanatomy. (8th ed). Wolters Kluwer. Waxman, S.G. (2017). Clinical Neuroanatomy. (28th ed). McGraw Hill.