CSF and Ventricular System

2. CSF and Ventricular System Dr. Nimir Dr. Safaa

3. Objectives • Describe the ventricles of brain and importance of their choroids plexus. • Summarize the pathway of cerebrospinal fluid (CSF) circulation. • Locate the safe sites for the lumbar puncture. • Identify brain ventricles in CT scan, MRI and ventriculograms.

4. Ventricles: • They are four fluid-filled cavities located within the brain, there are two lateral ventricles, third ventricle, and fourth ventricle. • Lateral ventricles(one in each hemisphere) communicate through interventricular foramina (of Monro) with third ventricle. • The third is connected to the fourth by cerebral aqueduct (of Sylvius).

5. Lateral Ventricles: • The ventricle is C-shaped cavity divided into a body, whithinparietal lobe, anterior horn in frontal lobe, posterior in occipital lobe, and inferiorin temporal lobe. • The body has: • Roof & lateral wall formed by corpus callosum. • Floor by body of caudate nucleus & thalamus. • Medial wall by septum pellucidum.

8. Anterior horn has: • Roof & lateral wall formed by anterior part of corpus callosum. • Floor by head of caudate nucleus. • Medial wall by septum pellucidum. • Posterior horn has: • Roof & lateral wall formed by fibers of tapetumof corpus callosum. • Medial wall formed superiorly by forceps major of corpus callosum & inferiorly by calcaravisof calcrine sulcus.

11. Inferior horn has: • Roof formed by fibers of tapetumof corpus callosum & tail of caudate nucleus . • Floorformed laterally by collateral eminence, produced by collateral fissure, and medially by hippocampus.

12. Choroid plexus of the lateral ventricle: • It is a vascular plexus composed of pia mater covered with ependymal lining of the ventricular cavity. • It enters the ventricle through choroid fissure between fornix & thalamus. • Its function is to produce cerebrospinal fluid.

13. Third Ventricle: • Is space between two thalami. • Its anterior wall is formed by lamina terminalis. • Its posterior wall is formed by epithalmus. • Its roof formed by telachoroidea below fornix and corpus callosum. • Its floor is formed by optic chiasma,tubercinereum, infundibulum, and mammillary bodies. • Its choroid plexuses is formed from telachoroidea. • It communicates with lateral ventricles through interventricular foramina (of Monro), and it communicates fourth ventricle through cerebral aqueduct.

15. Fourth ventricle: • It is anterior to cerebellum and posterior to pons and superior half of medulla oblongata. • Its floor (Rhomboid Fossa) formed by posterior surface of pons & upper medulla. • Its roof formed by superior medullary velum & inferior medullary velum.

16. Inferior medullary velum contains median aperture of Magendie & lateral apertures of Luschka through which CSF pass to subarachnoid space. • Its choroid plexus has a T shape which formed from highly vascular telachoroidea.

18. Cerebrospinal fluid (CSF) is formed in ventricles by choroid plexuses. • Pass from lateral ventricles to third through interventricular foramina then through cerebral aqueduct to fourth ventricle. • From fourth to subarachnoid space through foramina of Luschka & Magendie

19. Lumbar puncture: • With a careful aseptic technique and under local anesthesia, Lumbar puncture (spinal tap) needle, fitted with a stylet, is passed into the vertebral canal above or below the fourth lumbar spine.

20. A) Pre-operative axial head CT scan demonstrating enlarged ventricles.

21. B) Post-operative axial head CT demonstrating decrease in the size of the lateral and third ventricles after shunt placement.