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Anatomy of meninges, ventricles, cerebrospinal fluid


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Anatomy of meninges, ventricles, cerebrospinal fluid

  1. 1. MENINGES, VENTRICLES, CEREBROS PINAL FLUID AND BOOLD SUPPLY OF THE BRAIN Dr. Israa M. Sulaiman Dr. Mohammed Faez Department of Anatomy IMS/MSU
  2. 2. OBJECTIVES • Illustrate and describe the Meninges’s three membranes. • Describe the structure of the meninges, its blood supply and nerve supply. • Illustrate and describe the venous blood sinuses
  3. 3. The Meninges • The Meninges are the membrane covering the brain and spinal cord. • The Meninges consist of three membranes: 1. The dura mater, 2. The arachnoid mater, 3. The pia mater.
  4. 4. The Meninges
  5. 5. The Meninges 1. Dura mater - • 2. Arachnoid - strong, "Tough mother" spidery, holds blood a. Falx cerebri vessels b. Falx cerebelli c. Tentorium cerebelli • 3. Pia mater - d. Diaphragma sella "delicate mother"
  6. 6. The Meninges
  7. 7. 1) Falx cerebri 2) Tentorium cerebelli 4) Diaphragma sellae 3) Falx cerebelli Sagittal section showing the duramater
  8. 8. 1) Falx cerebri 2) Tentorium cerebelli Superior view showing the duramater
  9. 9. DURA MATER  Thick dense inelastic membrane and the outermost layer of the meninges  Bilaminar:  Endosteal layer (outer)  Meningeal layer (inner) These are closely united except along certain lines, where they separate to form venous sinuses.
  10. 10. DURA MATER  Endosteal layer ; o Periosteum - inner surface of the skull bones o Not continuous with dura mater of spinal cord  Meningeal layer ; o Dura mater proper o Covering the brain o Continuous with dura mater of spinal cord o Folded inwards as 4 septa between part of the brain o The function of these septa is to restrict the rotatory displacement of the brain.
  11. 11. duramater Superior cerebral veins beneath arachnoid
  12. 12. Superior sagittal sinus Dura mater (Dural venous sinus) Endosteal layer Meningeal layer They are closely united except along certain lines; they are separated to form venous sinuses Subdural space Coronal section of the upper part of the head
  13. 13. DURA MATER Dura mater septa: 1. Falx cerebri 2. Falx cerebelli 3. Tentorium cerebelli 4. Diaphragma sella
  14. 14. 1) Falx cerebri 2) Tentorium cerebelli 4) Diaphragma sellae 3) Falx cerebelli Sagittal section showing the duramater
  15. 15. The Falx Cerebri • It is a sickle-shaped fold of dura mater that lies in the midline between the two cerebral hemispheres. • Its narrow end in front is attached to the internal frontal crest and the crista galli. • Its broad posterior part blends in the midline with the upper surface of the tentorium cerebelli. • The superior sagittal sinus runs in its upper fixed margin, the inferior sagittal sinus runs in its lower concave free margin, and the straight sinus runs along its attachment to the tentorium cerebelli.
  16. 16. Superior sagittal sinus Falx cerebri Tentorium cerebelli Frontal crest Crista galli * Inferior sagittal sinus Straight sinus
  17. 17. The Tentorium Cerebelli • The tentorium cerebelli is a crescent-shaped fold of dura mater that roofs over the posterior cranial fossa. • It covers the upper surface of the cerebellum and supports the occipital lobes of the cerebral hemispheres.
  18. 18. Tentorium cerebelli Falx cerebri
  19. 19. The Falx Cerebelli • The falx cerebelli is a small, sickle-shaped fold of dura mater that is attached to the internal occipital crest and projects forward between the two cerebellar hemispheres. • Its posterior fixed margin contains the occipital sinus.
  20. 20. The Diaphragma Sellae • The diaphragma sellae is a small circular fold of dura mater that forms the roof for the sella turcica. • A small opening in its center allows passage of the stalk of the pituitary gland
  21. 21. Dural Nerve Supply • Branches of the trigeminal, vagus, and first three cervical nerves and branches from the sympathetic system pass to the dura. • The dura is sensitive to stretching, which produces the sensation of headache.
  22. 22. Dural Blood Supply Dural Arterial Supply Dural Venous Drainage • The dura mater’s arteries • The meningeal veins lie in supply from the internal the endosteal layer of dura. carotid, maxillary, ascending • The middle meningeal vein pharyngeal, occipital, and follows the branches of the vertebral arteries. middle meningeal artery • From a clinical and drains into the standpoint, the most pterygoid venous plexus or important is the middle the sphenoparietal sinus. meningeal artery, which is • The veins lie lateral to the commonly damaged in head arteries. injuries.
  23. 23. Arachnoid Mater  Delicate, impermeable & avascular membrane covering the brain  Lying between Pia mater (internally) & dura Mater(externally)  Separated from dura mater by a potential space, the subdural space (filled by a film of fluid)  Separated from pia mater by the subarachnoid space (filled with CSF)  The outer and inner surfaces covered with flattened mesothelial cells
  24. 24. Superior cerebral veins beneath arachnoid Arachnoid mater
  25. 25. Arachnoid mater Arachnoid projects into venous sinuses - sites for CSF diffuses into bloodstream Arachnoid granulations Arachnoid mater Arachnoid villi Subarachnoid space Subdural space
  26. 26. SUBDURAL SPACE : • Superior cerebral Superior cerebral veins beneath arachnoid veins, traverse the subdural space to reach the superior sagittal sinus and its lacunae
  27. 27. * Dura Arachnoid Subdural haematoma
  28. 28. Subarachnoid Space (SP) :  Relatively narrow over the surface of cerebral hemisphere, but sometimes becomes much wider in areas at the base of the brain, the widest space is called subarachnoid cisterns  The cisterna cerebellomedularis lies between inferior surface of the cerebellum and roof of 4th ventricle  The cisterna interpeduncularis lies between 2 cerebral hemispheres. All the cisternae are in free communication with one another & with the remainder of subarachnoid space
  29. 29. Superior cistern Chiasmatic cistern Interpeduncular cistern Pontine Cerebellomedullary cistern cistern Median sagittal section to show the subarachnoid cisterns & circulation of CSF
  30. 30. Pia mater Arachnoid Dura * Subarachnoid haemorrage
  31. 31. Pia Mater • Pia Mater is a vascular membrane covered by mesothelial cells. • Closely invests the brain, covering the gyri, descending into the deepest sulci & closely applied to the cortical surface.
  32. 32. Pia mater Pia mater
  33. 33. Pia Mater  It extends out over the cranial nerves & fuses with their epineurium  The cerebral arteries entering the substance of the brain, carry a sheath of pia mater with them  The pia mater forms the TELA CHOROIDAE .  The tela choroidae fuse with ependyma to form the choroid plexus  Choroid plexus forms CSF
  34. 34. Choroid plexus of lateral ventricle Ependyma Pia mater of tela choroidae Choroid plexus of 3rd ventricle Coronal section of the interventricular foramen showing the choroid plexus of 3rd & lateral ventricles
  35. 35. Read About The Venous Blood Sinuses
  36. 36. VENTRICLES
  37. 37. OBJECTIVES • Illustrate and describe the ventricles. • Describe the structure of the ventricles. • Illustrate and describe the cerebrospinal fluid (CSF) formation, absorption and circulation.
  38. 38. VENTRICLES(Ventricular System) • A ventricle is an internal cavity of the brain. Within the brain, which is filled with cerebrospinal fluid(CSF). • The ventricular system is composed of two lateral ventricles and two midline ventricles( third and fourth ventricles).
  39. 39. VENTRICLES(Ventricular System) • The chambers are connected to allow the flow of cerebrospinal fluid via two interventricular foramen (referred to as the foramen of Monro) and the cerebral aqueduct (referred to as the aqueduct of Sylvius).
  40. 40. Lateral ventricle Interventricular foramen (Monro) Cerebral aqueduct Fourth ventricle Third ventricle Central canal of medulla oblongata & spinal cord Lateral view to show the ventricular system of the CNS
  41. 41. VENTRICLES(Ventricular System) CONSISTS OF : 1) Lateral ventricle 2) Third ventricle 3) Fourth ventricle 4) Central canal of the medulla oblongata & spinal cord
  42. 42. 42
  43. 43. 43
  44. 44. Lateral Ventricles • The lateral ventricles are two curved shaped cavities located within the cerebrum. • The lateral ventricles are separated by the septum pellucidum and do not communicate directly
  45. 45. Lateral ventricle Parietal lobe Frontal lobe Occipital lobe Temporal lobe
  46. 46. Lateral ventricle  C-shaped cavity & may be divided into : 1. Body 2. Anterior 3. Posterior horn Third horn ventricle 4. Inferior horn Fourth ventricle Lateral view of the ventricular cavities of the brain
  47. 47. Posterior horn Anterior horn Inferior horn Lateral view to show the ventricular system of the CNS
  48. 48. Third ventricle  The third ventricle is a narrow cavity or a slitlike cleft between the 2 thalamus  Communicates ; • Anteriorly with lateral ventricles through interventricular foramina (of monro) • Posteriorly with fourth ventricle through cerebral aqueduct (of sylvius) Posterior view to show the ventricular system of the CNS
  49. 49. Third ventricle Parietal lobe Frontal lobe Occipital lobe Temporal lobe
  50. 50. Third ventricle ROOF Body of fornix Lateral wall Thalamus Third ventricle FLOOR Hypothalamus Coronal section of the brain (posterior view)
  51. 51. Fourth ventricle • The fourth ventricle Is a rhomboid or diamond shaped cavity. • It is a wide and flattened space located just anterior to the cerebellum and posterior to the upper, or superior, half of the medulla oblongata and the pons.
  52. 52. Fourth ventricle Fourth ventricle Cerebral aqueduct POSTERIOR ANTERIOR Cerebellum Pons Medulla oblongata (superior half) Central canal (spinal Sagittal section of the 4th ventricle cord)
  53. 53. Fourth ventricle Parietal lobe Frontal lobe Occipital lobe Temporal lobe
  54. 54. Roof or posterior wall of fourth ventricle : Superior part of the roof ; Superior medullary velum Cerebral aqueduct ANTERIOR POSTERIOR Pons Medulla oblongata (superior half) Inferior part of the roof ; Inferior medullary velum Fig. : Sagittal section of the 4th ventricle
  55. 55. Floor or rhomboid fossa of fourth ventricle : Medial sulcus Formed by ; (divides the floor into symmetrical halves) 1. Posterior surface of the pons Medial eminence 2. Cranial ½ Sulcus of the limitans medulla oblongata Facial colliculus Stria Posterior view of the medullaris 4th ventricle Vagal Hypoglossal (strands of nerve triangle triangle fibers)
  56. 56. CENTRAL CANAL  Opens superiorly into the fourth ventricle Fourth ventricle Extends ; Inferior ½ of medulla oblongata Central canal Entire (Lined with length of ependyma but no spinal cord choroid plexus in the central canal)
  57. 57. CENTRAL CANAL Parietal lobe Frontal lobe Occipital lobe Temporal lobe
  58. 58. Conus medullaris- Terminal ventricle
  60. 60. CHOROID PLEXUS • It is formed by invaginating of vascular pia mater into the Lateral ventricle ventricular cavity • It becomes highly convoluted & produce a spongy-like appearance • It enters the 3rd and 4th ventricles through their roofs, and the lateral ventricles through the choroid fissure Third ventricle • produces cerebrospinal fluid Fourth (CSF) ventricle
  61. 61. Pia Mater Choroid BODY OF Plexus of Cavity Of FORNIX The Lateral Lateral Ventricle Ventricle CORPUS CALLOSUM CN Pia Mater of Ependyma Tela THALAMUS Choroidae Cavity Of Choroid Third Plexus of Ventricle The Third Ventricle Blood supply derives from choroidal branches of the internal carotid & basilar arteries Coronal section of the cavities of the lateral and 3rd ventricles
  62. 62. Arachnoid mater Pia mater Ependyma Cavity of fourth ventricle CEREBELLUM Choroid plexus of the fourth ventricle •T shaped, vertical part is double • Horizontal part extends into lateral recesses of each ventricle (foramina of Luskha) • Blood supply ; posterior inferior cerebellar arteries
  63. 63. What is cerebrospinal fluid (CSF) ? • Clear, colorless fluid • Produced by the choroid plexus • Found in the :  Ventricles of the brain  Subarachnoid space (between Arachnoid + Pia mater) around the brain & spinal cord • The pressure of the CSF is kept remarkably constant. • Based on the Monro-Kellie doctrine : • “Volume of BLOOD, CSF & BRAIN at any time must be relatively constant”
  64. 64. Physical characteristics and composition of the CSF Appearance Clear and colourless Volume 130 ml Rate of production 0.5 ml/min Pressure 60-150 mm of water Composition protein 15-45 mg/100 ml glucose 50-85 mg/ 100 ml chloride 720-750 mg/100 ml No. of cells 0-3 lymphocytes/cu mm
  65. 65. Function of the CSF : 1. Cushions & protects the CNS from trauma 2. Provides mechanical buoyancy & support for the brain 3. Serves as a reservoir & 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
  66. 66. Sites of formation : 1. Choroid plexus of the ventricle cavities, mostly is formed in the LATERAL VENTRICLES 2. Some originate from the ependymal cells lining the ventricles 3. Some from the brain substances through perivascular spaces Movement of CSF inside the ventricle is controlled by the: 1. Pulsation of the artery in the choroid plexus 2. By the aid of the cilia & microvilli of the ependymal cells
  67. 67. 5 Superiorly = lateral aspect of Choroid plexus of each cerebral 1 the lateral ventricle hemisphere 2 3 Choroid plexus of 3.2 the 3rd ventricle 3.1 Choroid plexus of the 4th ventricle Inferiorly = subarachnoid 4 space around the brain & spinal cord
  68. 68. cerebrospinal fluid (CSF) • The CSF is formed in the lateral ventricles escapes by the foramen of monro into the third ventricle • From the third ventricle by the aqueduct into the fourth ventricle. • Then from the fourth ventricle the fluid is poured into the subarachnoid spaces through the medial foramen of majendie and the two lateral foramina of luschka. • There is no evidence that functional communications between the cerebral ventricles and the subarachnoid spaces exist in any region except from the fourth ventricle.
  69. 69. Site of formation Choroid plexus of the lateral ventricle 1. Lateral ventricle Superiorly Interventricular foramina Superiorly 2. Third ventricle Cerebral aqueduct Absorbed Absorbed 3. Fourth ventricle 3.2 Lateral 3.2 Lateral foramina foramina (Luschka) (Luschka) 3.1 Median foramen (Magendie) 4. Subarachnoid space Inferiorly
  70. 70. Circulation of CSF in subarachnoid space : Superior cistern Chiasmatic cistern Median Interpeduncular foramen of cistern 4th ventricle Pontine Cerebellomedullary cistern cistern Median sagittal section to show the subarachnoid cisterns & circulation of CSF
  71. 71. Factors that facilitate the flow of CSF in subarachnoid space ; 1. Pulsation of the cerebral & spinal arteries 2. Movements of the vertebral column 3. Respiration & coughing 4. Changing of the positions
  72. 72. Absorption of CSF into dural venous sinuses • Main sites - arachnoid villi (project into dural venous sinuses, especially, superior sagittal sinus) • Arachnoid villi are covered by endothelium of the venous sinus • Arachnoid villi tend to be grouped together & form elevations known as arachnoid granulations • CSF pressure >> the pressure in the sinus • The rate of absorption of CSF through the arachnoid villi controls the CSF pressure
  73. 73. CLINICAL APPLICATION Hydrocephalus • The term hydrocephalus is derived from the Greek words "hydro" meaning water and "cephalus" meaning head. • It is excessive accumulation of fluid in the brain.
  75. 75. OBJECTIVES • Illustrate and describe the formation of the circle of willis • Describe the blood supply of the brain – Arterial supply – Venous drainage
  76. 76. Blood Supply of The Brain • The brain receives it arterial supply from two pairs of vessels, the vertebral and internal carotid arteries which are interconnected in the cranial cavity to produce an arterial circle (of Willis).
  77. 77. Internal carotid artery
  78. 78. Internal Carotid Artery • Begins – bifurcation of Com Carotid A • Perforates base of skull – carotid canal • Enters middle cranial fossa beside dorsum sellae • In the cavernous sinus – Horizontal • Emerge out – medial side of Ant clinoid process – perforates dura & arachnoid mater – enters subarachnoid space • Turns posteriorly – below optic nerve • Turns upward – lateral to optic chiasma • Now is under anterior perforated susbtance • Divides – into ANTERIOR & MIDDLE cerebral arteries
  79. 79. Middle cerebral Posterior artery Anterior cerebral communicating artery artery Internal carotid artery in cavernous sinus Posterior cerebral artery Internal carotid artery Basilar artery In temporal bone External carotid artery Vertebral artery Common carotid artery
  80. 80. Vertebral Artery • Branch of first part of subclavian A • Passes – foramen transvesarium C6 – C1 • Enters through foramen magnum – perforates dura & arachnoid mater – enters subarachnoid space • Turns upward, forward, medially – medulla oblongata • Lower border of pons – joins opposite side – BASILAR artery
  81. 81. Middle cerebral Posterior artery Anterior cerebral communicating artery artery Internal carotid artery in cavernous sinus Posterior cerebral artery Internal carotid artery Basilar artery In temporal bone External carotid artery Vertebral artery Common carotid artery
  82. 82. Blood Supply of The Brain • VERTEBRAL • INTERNAL CAROTID – Basilar – Middle cerebral – Posterior cerebral artery – Anterior cerebral – Anterior communicating artery – Posterior communicating artery CIRCLE OF WILLIS
  83. 83. Branches of :- • VERTEBRAL • INTERNAL CAROTID – Basilar – ACA – PCA – MCA – Pontine – Ophthalmic – Labyrinthine – Ant ComA – Ant Inf CA – Post Com A – Sup cerebellar – Choroidal – Choroidal
  84. 84. • CEREBRAL (ICA) • CRANIAL (VERT) – Ophthalmic – Meningeal – Post Communicating – Post Spinal – Choroidal – Ant Spinal – Ant Cerebral – Post Inf Cerebellar • Cortical – Medullary • Central • (BASILAR) • Communicates with – Ant Comm Art – Pontine – Post Cerebral – Labyrinthine – Mid Cerebral – Ant Inf Cerebellar • Cortical – Sup Cerebellar • Central – Post Cerebral • Cortical • Central • Choroidal
  85. 85. Circle of Willis • Interpeduncular fossa – base of brain • Anastomosis – 2 internal carotid arteries – 2 vertebral arteries • In the subarachnoid space
  87. 87. Anterior communicating Anterior cerebral artery artery Internal Middle cerebral carotid artery artery Posterior communicating artery Sup cerebellar A Posterior cerebral artery Basilar A Ant Inf cerebellar A Post Inf cerebellar A Vertebral arteries
  88. 88. Anterior cerebral artery Middle cerebral artery Posterior cerebral artery
  89. 89. Central sulcus Superior parietal Superior frontal gyrus lobule Frontal pole Parieto- occipital sulcus Frontal pole Anterior cerebral artery
  90. 90. ANTERIOR CEREBRAL ARTERY LOBE AREA FRONTAL Motor – lower limb and perineum - LOBE pericentral lobule PARIETAL Sensory – lower limb and perineum - LOBE paracentral lobule
  91. 91. Anterior cerebral artery & anterior communicating artery Lentiform nucleus lentiform Caudate nucleus Internal capsule Internal capsule caudate (ANT) Hypothalamus (ANT)
  92. 92. Temporal pole Middle cerebral artery Central branches
  93. 93. Central branches Lateral striate arteries Medial striate Left middle Right middle arteries cerebral artery cerebral artery
  94. 94. MIDDLE CEREBRAL ARTERY LOBE AREA FRONTAL Motor – except for paracentral lobule Motor speech – esp left side PARIETAL Sensory – except for paracentral lobule Sensory speech TEMPORAL Auditory
  95. 95. Middle cerebral artery & anterior choroidal artery Lentiform nucleus lentiform Internal Caudate nucleus capsule caudate Internal capsule (ANT & POST)
  96. 96. Inferior temporal gyrus Posterior cerebral artery Inferior temporal gyrus
  98. 98. Posterior cerebral artery & posterior communicating artery Hypothalamus Thalamus (ANT) Internal capsule thalamus Cerebral peduncle Cerebral peduncle
  99. 99. Posterior lateral arteries Thalamus (POST) Geniculate bodies thalamus Cerebral peduncle Lateral Geniculate bodies Cerebral peduncle
  100. 100. ARTERIES to specific brain areas Corpus striatum Middle & lateral Anterior & striate Middle cerebral Internal capsule artery Thalamus PComA, basilar, PCA Midbrain PCA, supCerebellarA, basilar Pons Basilar, Ant, inf, supCerebellarA, Medulla Vertebral, ASA,PSA,PICA, basilar oblongata Cerebellum supCerebellar, AICA,PICA
  101. 101. VENOUS DRAINAGE of THE BRAIN • EXTERNAL • INTERNAL • SPECIFIC – Superior – Thalamo – Midbrain – Pons cerebral striate – Medulla – Superficial oblongata middle – choroidal – cerebellum cerebral – Deep middle cerebral
  102. 102. Superior cerebral Superior Sagittal sinus Superior Superficial Sagittal sinus Internal Middle cerebral cerebral Transverse Great sinus cerebral Straight sinus Inferior Sagittal sinus Occipital sinus basal
  103. 103. Superior Superior anastomotic V Superior cerebral Sagittal sinus Inferior anastomotic V Superficial Middle cerebral Transverse sinus
  104. 104. Superior Sagittal Inferior sinus Sagittal sinus Internal cerebral Great cerebral Straight sinus Site of junction with transverse sinus Occipital sinus basal
  105. 105. EXTERNAL CEREBRAL VEIN VEIN AREA DRAINS INTO Superior Superior sagittal cerebral Lateral surface of sinus Superficial cerebral Cavernous sinus middle hemisphere cerebral Deep middle Insula Joined by ant cerebral cerebral & striate- basal vein Sup anas V Superior sagittal sinus Inf anas V Inferior sagittal sinus
  106. 106. INTERNAL CEREBRAL VEIN VEIN AREA DRAINS INTO Thalamostriate Basal ganglia, Internal cerebral thalamus, vein - great Choroidal internal cerebral vein – capsule,Tela straight sinus choroidae of 3rd ventricle,hippo DURAL VENOUS campus SINUS
  107. 107. VEIN of specific areas Midbrain Basal, great cerebral Pons Basal, cerebellar Medulla oblongata Anterior & posterior spinal Cerebellum Great cerebral
  108. 108. Great cerebral Superior cerebral vein vein Superior sagittal sinus Straight sinus Inferior sagittal sinus Middle cerebral vein Medial aspect of Confluence of hemisphere Cavernous sinus sinus Superior Inferior petrosal petrosal sinus sinus Transverse sinus (R & L) IntJugular IntJugular vein vein Sigmoid sinus (R & L)
  109. 109. Inferior sagittal Superior sagittal sinus Falx cerebri sinus Tentorium cerebelli Superior petrosal sinus * Confluence of sinus Straight Inferior sinus Sigmoid Transverse petrosal sinus sinus sinus
  110. 110. Cavernous sinus Superior petrosal sinus Inferior petrosal sinus Jugular foramen Sigmoid sinus Straight sinus Transverse sinus Superiorsa gittal sinus Confluence of sinus
  111. 111. Cavernous sinus • Lateral to body of sphenoid bone • Connected to opposite – intercavernous S • Receives blood – Middle cerebral V • Drains into – Int Jugular V –via Inf petrosal sinus – Transverse S – via Sup petrosal S • Dural Venous sinuses – emissary veins – extracranial V
  112. 112. CLINICAL APPLICATION • Stroke or cerebrovascular accident:- – Blockage in the artery – cerebral infarction • Carotid artery • Basilar artery – Bleeding within the brain – intracerebral haemorrhage • Aneurysm • Subarachnoid haemorrhage • Intracerebral haemorrhage - hypertension – Damages one side of the body - contralateral
  113. 113. CVA – due to blockage
  114. 114. CVA – due to haemorrhage
  115. 115. THANK YOU