Ventricular System PDF

1 2 VENTRICULAR SYSTEM OF THE BRAIN consists of the intercommunicating 4 cavities; the 2 lateral ventricles, the third ventricle and the fourth ventricle. The 2 lateral ventricles are C-shaped cavities; one for each cerebral hemisphere. The third ventricle is a slit- like cavity, betwee...

1 2 VENTRICULAR SYSTEM OF THE BRAIN consists of the intercommunicating 4 cavities; the 2 lateral ventricles, the third ventricle and the fourth ventricle. The 2 lateral ventricles are C-shaped cavities; one for each cerebral hemisphere. The third ventricle is a slit- like cavity, between the two thalmi The fourth ventricle is the tent- like cavity behind the pons and medulla. 4 5  Lateral ventricle The largest ventricle. Inside each cerebral hemisphere. C-shaped. Each lateral ventricle is connected with the third ventricle through the interventricular foramen of Monro.  Lateral ventricle It has 4 parts : - Body (parietal lobe) above the thalamus. - Anterior horn (frontal lobe) anterior to the thalamus. - Posterior horn (occipital lobe) behind the thalamus. - Inferior horn (temporal lobe) below the thalamus  Anterior horn of lateral ventricle a. Roof : body of the corpus callosum. b. Anterior : genu of corpus callosum c. Floor : rostrum of corpus callosum. d. Medially : septum pellucidum. 9  Anterior horn of lateral ventricle Laterally : head of caudate. 10  Body of lateral ventricle a. Roof : body of the corpus callosum. b. Floor : thalamus, body of caudate, stria terminalis and thalamo-striate vein. c. Medially : septum pellucidum.  Posterior horn of lateral ventricle a. Roof : tapetum of the corpus callosum. b. Laterally : tapetum of the corpus callosum and optic radiation. c. Inferomedial wall: -Bulb of posterior horn (formed by forceps major) -Calcar avus (formed by calcarine sulcus)  Inferior horn of lateral ventricle a. Roof : thalamus, tail of caudate and amygdaloid body. b. Laterally : tapetum of the corpus callosum. 14  Third ventricle It is the cavity of the diencephalon. It lies between the two thalami.  Third ventricle a. Laterally : thalamus, hypothalamus and hypothalamic sulcus. b. Anteriorly : lamina terminalis. c. Posteriorly : the pineal body  Third ventricle e. Floor : optic chiasma, pituitary gland, infundibulum, mammillary bodies, posterior perforated substance and midbrain.  Third ventricle - The two thalami are connected by interthalamic connection or adhesion that traverses the third ventricle.  Openings of the third ventricle 1- It is connected with each lateral ventricle through the foramen of Monro. 2- It is connected with the fourth ventricle through the cerebral aqueduct of Sylvius which passes through the midbrain. Boundaries of third ventricle 21  Fourth ventricle - It lies between the cerebellum and brain stem (mainly the pons and upper part of the medulla). - It is the cavity of the hindbrain. - It is tent-shaped.  Fourth ventricle a. Roof : Superior and inferior medullary vela b. Laterally : superior cerebellar peduncles in the upper part and inferior cerebellar peduncles in the lower part.  Fourth ventricle c. Floor : It is a rhomboid fossa formed by the posterior surface of the pons and the upper part of the medulla.  Floor of fourth ventricle 1- The upper pontine part - Facial colliculus. - Superior fovea. - Superior vestibular area.  Floor of fourth ventricle 2- The lower medullary part - Inferior fovea : an inverted V-shaped sulcus. - Hypoglossal triangle (medial). - Vagal triangle (middle). - Inferior vestibular triangle (lateral).  Openings of the fourth ventricle 1- Cerebral aqueduct of Sylvius : with the third ventricle. 2- Median foramenof Magendi 3- Lateral foramina of Luschka. - connect the ventricle with the subarachnoid space. 4- inferiorly : connected with the central canal of the medulla oblongata and the spinal cord.  Fourth ventricle ❑It communicates with: 1. Subarachnoid space (through 3 foramina ) 2. Third ventricle (through aqueduct of midbrain). 3. Central canal of spinal cord. ventricular system Dr Melad N Kelada 28 CSF Circulation  Communications inside the ventricular system (CSF pathway) The 2 lateral ventricles communicate with the third ventricle through the interventricular foramina of Monro (one between each lateral ventricle and the third ventricle). The 3rd ventricle communicates with the 4th ventricle through the cerebral aqueduct (aqueduct of Sylvius) 30  Circulation of CSF - From the fourth ventricle, it flows to : 1- Subarachnoid space through the median foramen of Magendi and lateral foramina of Luschka. 2- Little amount through the central canal of the medulla and spinal cord. - Then, CSF circulates in the subarachnoid space around the spinal cord and the brain.