5. Ventricular System, Choroid Plexus and CSF (4).pdf

VENTRICULAR SYSTEM, CHOROID PLEXUS AND CSF DR NADINE RAMPF | PHD [email protected] LECTURE OUTLINE Ventricles of the brain 04 Choroid plexus 17 Cerebrospinal fluid 19 Clinical correlations 22 02 OBJECTIVES Identify the ven...

VENTRICULAR SYSTEM, CHOROID PLEXUS AND CSF DR NADINE RAMPF | PHD [email protected] LECTURE OUTLINE Ventricles of the brain 04 Choroid plexus 17 Cerebrospinal fluid 19 Clinical correlations 22 02 OBJECTIVES Identify the ventricles and list their subdivisions and relations in the cerebrum and brainstem Identify and describe the choroid plexus and its role in the production of CSF Explain how CSF is created and describe its flow and reabsorption into the systemic circulation Define and briefly describe hydrocephalus 03 LECTURE OUTLINE Ventricles of the brain Choroid plexus Cerebrospinal fluid Clinical correlations 04 VENTRICULAR SYSTEM OF THE BRAIN Interconnecting series of chambers and channels Derived from the embryonic neural tube In spinal cord is represented by the central canal Lined with ependyma and contain CSF Contain choroid plexus, which produces CSF at a rate of 500 to 700 ml/day Communicate with the subarachnoid space via three foramina in the fourth ventricle 05  LATERAL VENTRICLES Paired, approximately C-shaped structures Located within the cerebral hemispheres Body Derived from the telencephalon embryonically Communicate with the third ventricle via the interventricular foramina (of Monro) Interventricular foramen located between the column of the fornix and the anterior pole of the thalamus Consist of five parts: Frontal (anterior) horn Body Temporal (inferior) horn Occipital (posterior) horn Trigone (atrium) 06 CoCb SP CoCg LATERAL CoCr VENTRICLES Frontal (anterior) horn LVa CoCb Located in the frontal lobe, anterior to the interventricular foramen SP Triangular in cross-section CN CN CoCr Roof is formed by body the corpus callosum Floor is formed by the head of the caudate nucleus and small contribution from the rostrum of the corpus callosum Anterior wall is formed by the posterior surface of the genu and rostrum of the corpus callosum Lateral wall is formed by the head of the caudate nucleus Medial wall is formed by the septum pellucidum Septum pellucidum: Thin sheet that spans between the corpus callosum and fornix in the midline Separates the anterior horns of the two lateral ventricles Lacks choroid plexus CoCb: Corpus callosum body CN: Caudate nucleus CoCg: Corpus callosum genu LVa: Lateral ventricle anterior horn CoCr: Corpus callosum rostrum SP: Septum pellucidum 07  LATERAL VENTRICLES LVb Body CoCb Located in the medial portion of the frontal CN SP and parietal lobes Fo Extends from the interventricular foramen to Th the splenium of the corpus callosum Floor formed by the thalamus and caudate nucleus Medial wall is formed by septum pellucidum with fornix lying inferiorly Contains choroid plexus Communicates with the third ventricle via the interventricular foramina CoCb: Corpus callosum body LVb: Lateral ventricle body CN: Caudate nucleus SP: Septum pellucidum Fo: Fornix Th: Thalamus 08  LATERAL VENTRICLES Occipital (posterior) horn Located in the parietal and occipital lobes Begins at the spelenium of the corpus callosum and curves backwards and medially into the occipital lobe Sometime absent Roof, lateral wall and floor are formed by LVa fibres of the tapetum of the corpus callosum Lacks choroid plexus p p LVp CoCs: Corpus callosum splenium LVa: Lateral ventricle anterior horn FMa: Forceps major LVp: Lateral ventricle posterior horn FMi: Forceps minor Ta: Tapetum of corpus callosum 09  LATERAL VENTRICLES Temporal (inferior) horn Located in the medial part of the temporal lobe Extends forwards and laterally into the temporal lobe and then turns medially towards the uncus Alv: Alveus AM: Aqueduct of midbrain Roof is formed by the tail of the caudate ChP: Choroid plexus CNt: Caudate nucleus tail nucleus Fi: Fimbria Floor is formed by the hippocampus Hi: Hippocampus LGB: Lateral geniculate body Lateral wall is formed by the tapetum of the LVi: Lateral ventricle inferior horn MGB: Medial geniculate body corpus callosum V3: 3rd ventricle Medial wall is deficient and made of ependyma, which has been pushed into the cavity by the pia mater to form the choroid plexus of the temporal horn Contains choroid plexus 10  LATERAL VENTRICLES Lateral Ventricles Trigone (atrium) Found at the junction of the body, occipital horn, and temporal horn of the lateral ventricle Alv: Alveus Contains the glomus, a large tuft of choroid At: Atrium ChP: Choroid plexus plexus, which is calcified in adults and is visible CN: Caudate nucleus on x-ray film and computed-tomography (CT) Fi: Fimbria Fo: Fornix Hi: Hippocampus LVi: Lateral ventricle inferior horn 11  THIRD VENTRICLE AC: Anterior commissure AM: Aqueduct of midbrain A slit-like vertical midline cavity of the diencephalon ChP: Choroid plexus Fo: Fornix Derived from the diencephalon embryonically HthSu: Hypothalamic sulcus Communicates with the lateral ventricles via the IA: Interthalamic adhesion IF: Interventricular foramen interventricular foramina and with the fourth LT: Lamina terminalis ventricle via the cerebral aqueduct LV: Lateral ventricle MB: Mammillary body Roof is formed by ependyma invaginated on each OC: Optic chiasm side of the midline by pia mater PB: Pineal body PC: Posterior commissure Floor is formed the hypothalamus and subthalamus Th: Thalamus Anterior wall consists of the lamina terminalis, and TC: Tuber cinereum V3: 3rd ventricle superiorly, the anterior commissure V4: 4th ventricle Posterior wall is formed by the posterior commissure and pineal body/gland Lateral wall is formed by the thalamus and interthalamic adhesion superiorly and hypothalamus inferiorly Demarcation between thalamus and hypothalamus indicated by the hypothalamic sulcus Contains choroid plexus in its roof www.sites.uclouvain.be/braininteratlas/en 12  CEREBRAL AQUEDUCT Derived from the mesencephalon embryonically Lies in the midbrain and is surrounded by periaqueductal grey matter Connects the third ventricle with the fourth ventricle Lacks choroid plexus Blockage leads to hydrocephalus (aqueductal stenosis) AM: Aqueduct of midbrain SCo: Superior colliculus ICo: Inferior colliculus V3: 3rd ventricle Mb: Midbrain V4: 4th ventricle 13  FOURTH VENTRICLE Lies on the dorsal surface of the brainstem beneath the cerebellum Rostral portion of ventricle derived from the metencephalon embryonically Caudal portion of ventricle derived from the myelencephalon embryonically Diamond-shaped cavity Has two lateral angles where inferior SMV cerebellar peduncles meet the pons LR Extensions of these angles known as lateral recesses: SaS Ob Contains ependyma Open into the pontine cistern in the subarachnoid space via the lateral CeC apertures (of Luschka) AM: Aqueduct of midbrain ICo: Inferior colliculus Ob: Obex SCP: Superior cerebellar peduncle Ce: Cerebellum LR: Lateral recess Po: Pons SMV: Superior medullary velum T-shaped choroid plexus suspended from roof CeC: Central canal Mb: Midbrain SaS: Subarachnoid space V3: 3rd ventricle ChP: Choroid plexus MO: Medulla oblangata SC: Spinal cord V4: 4th ventricle 14  FOURTH VENTRICLE Roof Tent-shaped and protrudes into the cerebellum Can be divided into three parts rostrocaudally: Rostral part: Formed on either side by the converging superior cerebellar peduncles V-shaped gap between the cerebellar peduncles bridged by the superior medullary velum Inferior medullary velum: Thin, incomplete sheet of tissue Attached to cerebellum rostrally Continuous with ependymal part of the roof of the 4th ventricle caudally Caudal part: Composed of ventricular ependyma Contains a median aperture (of Magendie) AM: Aqueduct of midbrain PCS: Superior cerebellar peduncle Fl: Flocculus SMV: Superior medullary velum that opens into the cerebellomedullary MA: Median aperture V4: 4th ventricle PCI: Inferior cerebellar peduncle cistern in the subarachnoid space 15  23 FOURTH 22 VENTRICLE 21 Floor 20 Called the rhomboid fossa 19 Broad in its midpoint and narrows rostrally and causally 18 Median groove divides the floor into symmetrical halves Median eminence (5) located on each side of the groove 17 8 Each half then further subdivided into medial and lateral areas by the sulcus limitans (19) 9 16 Stria medullares of the 4th ventricle (18) demarcates medulla and pontine regions Facial colliculi (6) 13 Circular elevations in the rostral part of the floor Indicates where fibres of the facial nerve loop around the nuclei of 14 the abducent nerves 15 Locus coeruleus (21) Located at the rostral end of the sulcus limitans Floor has a blue appearance due to the presence of pigmented 1: Middle cerebellar peduncle 6: Facial colliculus 12: Gracile tubercle 18: Stria medullaris of 4th ventricle cells 2: Superior cerebellar peduncle 7: Hypoglossal triangle 13: Posterolateral sulcus 19: Sulcus limitans Vestibular area (4) 3: Inferior cerebellar peduncle 8: Vagal triangle 14: Posterior intermediate sulcus 20: Superior fovea 4': Vestibular area (medulla) 9: Area posterma 15: Posterior median sulcus 21: Locus coeruleus Part of floor lateral to the sulcus limitans 4": Vestibular area (pons) 10: Trigeminal tubercle 16: Obex 22: Trochlear nerve Most of the vestibular nuclear complex lies beneath it 5: Median eminence 11: Cuneate tubercle 17: Inferior fovea 23: Frenulum of superior medullary velum Hypoglossal (7) and vagal triangles (8) Part of floor medial to the sulcus limitans and caudal to the striae medullares 16 LECTURE OUTLINE Ventricles of the brain Choroid plexus Cerebrospinal fluid Clinical correlations 17 CHOROID PLEXUS Highly vascularized structure anchored to the wall of the brain ventricle and floating in the CSF Formed by the invagination of the pia mater into the ventricles The primary site of CSF production Its structure reflects its secretory role: Villous appearance Single-layer of specialized simple cuboidal epithelium (aka ependymal cells) Core of connective tissue containing blood vessels Ependymal cells Have apical surface specializations Cilia and microvilli Lack a typical basement membrane Tight junctions between cells give rise to the blood-CSF barrier Function of blood-CSF barrier: Helps to maintain homeostasis of the internal environment of the brain and CNS Maintain ionic homeostasis 18 LECTURE OUTLINE Ventricles of the brain Choroid plexus Cerebrospinal fluid Clinical correlations 19  CSF CSF CIRCULATION Clear, colourless, acellular fluid located in the cranial and spinal subarachnoid spaces and ventricular system of the brain Formation: Produced by the choroid plexus through a process involving active secretion and passive diffusion Continuously produced at a rate of 0.2-0.7ml/min ± 500-700 ml of newly produce CSF/day Replaced ± 4 times/day Total combined volume ± 150 ml Composition: Contains no more than 5 lymphocytes/μl and is usually sterile Other normal values are: pH: 7.35 Specific gravity: 1.007 Glucose: 66% of plasma glucose Total protein: