Brain CT Anatomy and Basic Interpretation Part II
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The document details the anatomy and function of the brain's ventricles and cerebrospinal fluid (CSF). It describes the structure of the ventricular system, the production and circulation of CSF, and highlights the brain's blood supply through the Circle of Willis. The text also outlines the major subarachnoid cisterns and the organization of the brain's lobes, gyri, and sulci.
Brain CT Anatomy and Basic Interpretation Part II
- 1. DR SAKHER AL-KHADERI CONSULTANT RADIOLOGIST AMC BRAIN CT ANATOMY AND BASIC INTERPRETATION PART II
- 2. VENTRICLES
- 3. OBJECTIVES Illustrate and describe the ventricles. Describe the structure of the ventricles. Illustrate and describe the cerebrospinal fluid (CSF) formation, absorption and circulation.
- 4. 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).
- 5. 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).
- 6. Lateral view to show the ventricular system of the CNS Central canal of medulla oblongata & spinal cord Fourth ventricle Lateral ventricle Third ventricle Interventricular foramen (Monro) Cerebral aqueduct
- 7. VENTRICLES(Ventricular System) CONSISTS OF : 1) Lateral ventricle 2) Third ventricle 3) Fourth ventricle 4) Central canal of the medulla oblongata & spinal cord
- 10. LateralVentricles 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
- 11. Lateral ventricle Frontal lobe Parietal lobe Temporal lobe Occipital lobe
- 12. C-shaped cavity & may be divided into : 2. Anterior horn 1. Body 3. Posterior horn 4. Inferior horn Third ventricle Fourth ventricle Lateral view of the ventricular cavities of the brain Lateral ventricle
- 13. Anterior horn Inferior horn Posterior horn Lateral view to show the ventricular system of the CNS
- 14. 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 Third ventricle
- 15. Frontal lobe Parietal lobe Temporal lobe Occipital lobe Third ventricle
- 16. Third ventricle Hypothalamus Coronal section of the brain (posterior view) Third ventricle Thalamus ROOF FLOOR Lateral wall Body of fornix
- 17. 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.
- 18. Cerebellum Pons Medulla oblongata (superior half) Sagittal section of the 4th ventricle Cerebral aqueduct Central canal (spinal cord) Fourth ventricle Fourth ventricle ANTERIOR POSTERIOR
- 19. Frontal lobe Parietal lobe Temporal lobe Occipital lobe Fourth ventricle
- 20. Pons Medulla oblongata (superior half) Fig. : Sagittal section of the 4th ventricle Cerebral aqueduct ANTERIOR POSTERIOR Superior part of the roof ; Superior medullary velum Inferior part of the roof ; Inferior medullary velum Roof or posterior wall of fourth ventricle :
- 21. CENTRAL CANAL Opens superiorly into the fourth ventricle Fourth ventricle Inferior ½ of medulla oblongata Entire length of spinal cord Central canal (Lined with ependyma but no choroid plexus in the central canal) Extends ;
- 22. Frontal lobe Parietal lobe Temporal lobe Occipital lobe CENTRAL CANAL
- 25. CHOROID PLEXUS It is formed by invaginating of vascular pia mater into the 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 produces cerebrospinal fluid (CSF) Lateral ventricle Third ventricle Fourth ventricle
- 26. 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”
- 27. 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
- 28. 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
- 29. Sites of formation : 1. Choroid plexus of the ventricle cavities, mostly is formed in the LATERALVENTRICLES 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
- 30. 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.
- 31. Choroid plexus of the lateral ventricle Site of formation 1. Lateral ventricle 2.Third ventricle Interventricular foramina 3. Fourth ventricle Cerebral aqueduct 3.2 Lateral foramina (Luschka) 3.1 Median foramen (Magendie) 3.2 Lateral foramina (Luschka) 4. Subarachnoid space Inferiorly Superiorly Absorbed Superiorly Absorbed
- 32. Median sagittal section to show the subarachnoid cisterns & circulation of CSF Superior cistern Interpeduncular cistern Cerebellomedullary cistern Chiasmatic cistern Pontine cistern Circulation of CSF in subarachnoid space : Median foramen of 4th ventricle
- 33. Factors that facilitate the flow of CSF in subarachnoid space ; – Pulsation of the cerebral & spinal arteries – Movements of the vertebral column – Respiration & coughing – Changing of the positions
- 34. 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
- 37. OBJECTIVES Illustrate and describe the formation of the circle of willis Describe the blood supply of the brain Arterial supply Venous drainage
- 38. Blood Supply ofThe 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 (ofWillis).
- 40. 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
- 41. 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
- 42. Blood Supply ofThe Brain VERTEBRAL Basilar Posterior cerebral artery INTERNAL CAROTID Middle cerebral Anterior cerebral Anterior communicating artery Posterior communicating artery CIRCLE OFWILLIS
- 43. Branches of :- VERTEBRAL Basilar PCA Pontine Labyrinthine Ant Inf CA Sup cerebellar Choroidal INTERNAL CAROTID ACA MCA Ophthalmic Ant ComA Post Com A Choroidal
- 44. Circle of Willis Interpeduncular fossa – base of brain Anastomosis 2 internal carotid arteries 2 vertebral arteries In the subarachnoid space
- 45. Vertebral arteries BasilarA Posterior cerebral artery Posterior communicating artery Internal carotid artery Middle cerebral artery Anterior cerebral artery Anterior communicating artery Post Inf cerebellarA Sup cerebellarA Ant Inf cerebellar A
- 46. Middle cerebral artery Anterior cerebral artery Posterior cerebral artery
- 47. 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
- 48. POSTERIOR CEREBRAL ARTERY LOBE AREA OCCIPITAL Visual TEMPORAL Olfactory
- 49. ARTERIES to specific brain areas Corpus striatum Middle & lateral striate Anterior & Middle cerebral artery Internal capsule Thalamus PComA, basilar, PCA Midbrain PCA, supCerebellarA, basilar Pons Basilar, Ant, inf, supCerebellarA, Medulla oblongata Vertebral, ASA,PSA,PICA, basilar Cerebellum supCerebellar, AICA,PICA
- 50. VEIN of specific areas Midbrain Basal, great cerebral Pons Basal, cerebellar Medulla oblongata Anterior & posterior spinal Cerebellum Great cerebral
- 51. Superior sagittal sinus Inferior sagittal sinus Straight sinus Superior cerebral vein Medial aspect of hemisphere Great cerebral vein Transverse sinus (R & L) Sigmoid sinus (R & L) Confluence of sinus IntJugular vein IntJugular vein Cavernous sinus Middle cerebral vein Inferior petrosal sinus Superior petrosal sinus
- 52. The subarachnoid cisterns are areas within the subarachnoid space where the pia mater and arachnoid membrane are not in close approximation.The subarachnoid tissue is not as abundant here as in the normal subarachnoid space and cerebrospinal fluid (CSF) gathers to form pools or cisterns (Latin: "box"). Some major subarachnoid cisterns: cisterna magna (cerebellomedullary cistern): the largest of the subarachnoid cisterns pontine cistern suprasellar cistern interpeduncular cistern quadrigeminal cistern (superior cistern or cistern of the great cerebral vein) ambient cistern
- 53. Sulcus : A sulcus is depression or fissure in the surface of the brain. ( valleys ) Gyrus : A gyrus is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci ( hills )
- 54. Typical continous fissure Interhemispheric fissure Sylvian fissure ( lateral sulcus ) Parieto-occipital fissure Collateral sulcus Central sulcus Calcarine Sulcus
- 55. Interhemispheric fissure Deep sulcus upto corpus collosum Divides brain into two hemisphere
- 56. Sylvian fissure deep, mostly horizontal insula is buried within it separates temporal lobe from parietal and frontal lobes
- 57. Parieto - occipital fissure very deep oftenY-shaped from sagittal view X-shaped in horizontal and coronal views
- 58. Collateral sulcus Divides lingual and parahippocampal gyri from fusiform gyrus.
- 59. Central sulcus usually freestanding (no intersections) Seperates frontal and parietal lobe.
- 60. Calcarine sulcus
- 61. Lobes of brain Frontal lobe. Parietal lobe. Temporal lobe. Occipital lobe. Limbic lobe. Insular lobe.
- 62. • Frontal lobe: Anterior region of hemisphere; anterior to central sulcus, superior to sylvian fissure • Parietal lobe: Posterior region of hemisphere; posterior to central sulcus, anterior to parietooccipital sulcus • Occipital lobe: Posterior to parietooccipital sulcus • Temporal lobe: Inferior to sylvian fissure, anterior to angular gyrus
- 64. Lateral surface of brain
- 65. Medial surface of brain
- 66. Basal surface of brain
- 67. B R A I N CTANATOMY
- 85. THE END
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