The Ventricilar System

Slide 3(until page 16) Record of section 1 The ventricilar system: From wiki: The ventricular system is a set of four interconnected cavities (ventricles) in the brain, where the cerebrospinal fluid (CSF) is produced. Within each ventricle is a region of choroid plexus, a network of ependymal cells involved in the production of CSF. First we will start with the biggest one which is the lateral ventricle: What is the septum that close the lateral ventricleà 1-septum pellucidum àlink upper border of the fornix with the corpus callousm. The fornix is coming from the axons of fimbria of the hippocampus and forms an arch over the thalamus. in sagittal section, It is located on the medial aspects of the cerebral hemispheres.) Its divided to anterior column,body,posterior colum or (crura) Body of the two fornices is connected by fornix (hippocampal) commissure. The cavities of the lateral ventricle: 1-Anterior horn (frontal horn) 2- Posterior horn occipital l horn) 3-Infereior horn (temporal horn) 4-the body of the lateral ven. In the (partial lobe) If we take an imaginary line from the interventricular foramen (foramen of monro) which is located in front of the thalamus to the midpoint body of corpus callosum. 1|Page Anterior to this line à anterior horn or frontal horn Posterior to this line until the splenum of corpus callosumàthe body) Behind the splenum à posterior horn of the lateral ventricle But where is the inferior horn?? As we said in the temporal lobe. 10:00 Note: The only connection between the lateral and 3rd ventricle is the interventricular foramen Trigon of the lateral vent. : The most posterior part of the bod of the L.V at the junction of inferior and posterior horns Contains the glomus (choroid plexus tuft) Choroid plexus àit is a tuft of capillaries covered by ependyma àa layer from pia matter lining the 2|Page ventricle, And the covers the choroid plexus. Ø Ependyma is the thin neuroepithelial lining of the ventricular system of the brain and the central canal of the spinal cord, made up of ependymal cells. The choroid plexus is responsible for all the blood supply of the ventricle We have another 2 plexuses in the 3rd and 4th ventricles . Superior view for the L.V: Notes all the flowing Number 1,2,3,4,,8, are representing different parts of lateral ventricle. the red point which is the corpus callosum 3|Page Important note: The choroid plexus enters the lateral ventricle from its medial wall and it’s medially related to it Number 5,6,11 Noteà above 9 is the 3rd ventricle opining 4|Page The relations to the body of the lateral ventricle When the brain stem appear in a coronal section it is most likely taken in the body of L.V The roof àbody of corups collosum The floorà body of caudate nucleus medial to it ,the thalamus (body is related to body related to body ) Medial wallà septum pellucidum and the body of fornix More aboutstria terminalis: Start from the amygdala and ascend in the upper border of the thalamus joining the hypothalamus The arching fibers will be between the thalamus and caudate N. that’s why you will see the stria terminalis in the floor of the L.V. 5|Page What is the function of this connection between the amygdala and the hypothalamus???? To connected the olfaction with the hypothalamus When you smell a tasty food à the stria terminalis will send signal to the hypothalamus àsecretion of saliva andinduce gastric motility The shadow seen in the picture below is for the body of caudate N. The relation of the head of caudate N. to the anterior horn à lateral wall of it From the outside we can see a fissure (choroid fissure) which lies between the thalamus and the fornix This fissure is the enterance of the choroid plexus to the cavity of the lateral ventricle, which is formed by the posterior choroidal and anterior choroidal arteries 6|Page Dot forget the choroid plexus give the blood supply to the ventricle After age 40 in normal situations , the choroid plexus in the trigone of the lat ventriclewill calcify and appear as a white spots in the CT scan (the glomus). Relations of anterior horn of lateral ventricle: The Coronal section is taken in the more anterior part of the brain (the cut in the frontal lobe only). The anterior horn of the L.V: Roof : genu of the Corpus callosum Floor and lateral wall: Head of Caudate Nucleus (making a bulge) Medial wall: Rostrum of corpus callosum Septum Pellucidum Anterior column of the Fornix 7|Page Relations of Posterior horn of the lateral ventricle: The posterior horn is in the occipital lope Revition : 1-The calcrine sulcus begins near the occipital pole the visual area is represented on the limb of the calcrine sulcus (area 17) sheet 11. 2- parieto-occioital fissure The calcrine sulcus make an elevation in the posterior horn forming the calcar avis on the medial wall of the posterior horn. Also the splenium of corpus callosum form a bulge in the wall of the posterior horn called the (bulb). So the Medial wall: two convexities: Upper (bulb of the posterior horn) from the Splenium of the corpus callosum (bulb) Lower(posteriorly ) (Calcar avis) From Calcarine sulcus. If Calcar avis is well developed, it obliterates the posterior horn. •Roof and lateral wall Tapetum of the corpus callosum Optic radiation lying against the 8|Page tapetum in the lateral wall. What is the tapetumà fibers extending from the body of corpus callosun to the parietal lobe and temporal lobe. Relations of Inferior horn of the lateral ventricle: Last10 min •Roof Tail of the caudate nucleus, amygdaloid body •Lateral wall Tapetum of corpus callosum •Floor medially - hippocampus laterally - collateral eminence (by collateral fissure) 9|Page Here also the collateral sulcus posing the floor of the inferior horn forming the collateral eminence. Lower part of choroid plexus enter this horn from the temporal part of the choroid fissure. Choroid plexus of Lateral Ventricle Formed by posterior choroid branch of PCA (body) and anterior choroid branch of ICAàinternal carotid artery (inferior horn) It is a tuft of capillaries invaginating the cavity of the lateral ventricle or the roof of the 3rd ventricle 10 | P a g e In the dawn below picture you have a half of Coronal section we can see only one cavity of the lateral ventricle and the 3rd ventricle between the 2 thalami In the roof of the 3rd ventricle and the medial wall of the lateral the pia matter forming a double layer inside it the choroid plexus and this structure is called tela choroidea. Anatomical localization of the tela choroidea?? Enter from the medial wall of the L.V And from the roof of the 3rd V and 4th V From the slides: 1. Choroid plexus projects into the lateral ventricles on its medial aspect 2. Composed of pia matter covered with ependymal lining of the ventricle. 11 | P a g e 3. Choroid plexus is made of tela choroidea (two layers of pia matter). 4. Lies between fornix superiorly and thalamus inferiorly. 5. Situated in the inferior horn of the lateral ventricle. Projects into the choroid fissure How to know the anterior from the posterior part??? The longitudinal fissure shorter anteriorly. (# 9) 12 | P a g e 13 | P a g e Very important picture: You can see the cavity of the 3rd ventricle, the fornix ,cavity of septum pellucidum and many other structures 14 | P a g e