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  2. 2. Able to describe the general structure of the Cerebrum and Cerebral Cortex. Able to identify the Cerebrum, the Lobes of the Brain, the Cerebral Cortex, and its major regions/divisions. Able to describe the primary functions of the Lobes and the Cortical Regions of the Brain. Objectives
  3. 3. INTRODUCTION <ul><li>The cerebrum is the largest part of the brain with two hemisphere.The two cerebral hemisphere are linked by commisural fibres of corpus callosum. </li></ul><ul><li>Each cerebral hemisphere contains externally highly convulated cortex of grey matter and internal mass of white matter or medulla . </li></ul><ul><li>Each cerebral hemisphere contains lateral venticle continous with the third ventricle through interventricular foramen. </li></ul><ul><li>The cerebral hemispheres contains motor and sensory areas and the limbic system. </li></ul><ul><li>Each cerebral cortex is often divided phylogenetically into old allocortex,consisting of archicortex and paleocortex and a newer neocortex. </li></ul>
  4. 4. Longitudinal Fissure Cerebral hemisphere
  5. 5. Cortex and medulla
  6. 6. Surfaces of cerebral hemisphere <ul><li>Each cerebral hemisphere has three surfaces </li></ul><ul><li>Superolateral surface </li></ul><ul><li>Medial surface </li></ul><ul><li>Inferior surface . </li></ul><ul><li>Inferior surface further divided into two </li></ul><ul><li>Orbital surface </li></ul><ul><li>Tentorial surface </li></ul>
  7. 7. Surfaces of cerebral hemisphere………contd. <ul><li>Superolateral surface </li></ul><ul><li>It follows the concavity of the cranial vault </li></ul><ul><li>Medial surface </li></ul><ul><li>It is flat and vertical and seperated from its fellow by the great longitudinal fissure and falx cerebri. </li></ul><ul><li>Inferior surface </li></ul><ul><li>Inferior surface or the basal surface is irregular and divided into orbital and tentorial surface. </li></ul>
  8. 8. Superolateral Medial surface Surfaces of the brain
  9. 9. Inferior surface Orbital surface Tentorial surface
  10. 10. Borders of cerebral hemisphere Superomedial border Inferior border
  11. 11. Occipital pole Frontal pole Temporal pole Poles of the brain
  12. 12. Lobes of the brain <ul><li>Four lobes are present </li></ul><ul><li>Frontal </li></ul><ul><li>Parietal </li></ul><ul><li>Occipital </li></ul><ul><li>Temporal </li></ul><ul><li>Occasionally insula is considered as the fifth lobe </li></ul>
  13. 13. Gyrus and sulcuses <ul><li>Each cerebral hemisphere shows a complex pattern of convulation called Gyrus </li></ul><ul><li>The gyruses are separated by furrows of varying length called Sulci. </li></ul><ul><li>The convulated structure increases the cortical volume to three times what it would be if the surface is smooth. </li></ul><ul><li>The area of the cerebral cortex is 2200cm² </li></ul>Sulci (Groove) Fissure (Deep groove) Gyri (Elevation)
  14. 14. Important sulci and gyri <ul><li>In the suprolateral surface: </li></ul><ul><li>Lateral sulcus </li></ul><ul><li>Deep cleft on the lateral and inferior surface </li></ul><ul><li>It has a stem which divides into three rami:anterior,ascending,p-osterior. </li></ul><ul><li>The floor of the posterior ramus is the insula which is hidden cortex. </li></ul>Lateral sulcus Central sulcus
  15. 15. Important sulcus and gyrus…….contd . <ul><li>ii. The central sulcus </li></ul><ul><li>It is the boundary between frontal and parietal lobes </li></ul><ul><li>It starts at the superomedial border, a little behind the midpoint between frontal and occipital poles.It runs downards and forwards for about 8-10cm to end little above the posterior ramus of lateral sulcus. </li></ul><ul><li>It demarcates the motor and sensory area of the cerebral cortex. </li></ul><ul><li>iii. The other known sulcuses are </li></ul><ul><li>superior frontal sulcus </li></ul><ul><li>Inferior frontal sulcus </li></ul><ul><li>Precentral sulcus </li></ul><ul><li>Postcentral sulcus </li></ul>
  16. 16. Medial surface <ul><li>In the medial surface </li></ul><ul><li>The commisural fibres of the corpus callosum lies in the depth of longitudinal fissure </li></ul><ul><li>Parts of corpus callosum </li></ul><ul><li>Rostrum </li></ul><ul><li>Genu </li></ul><ul><li>Trunk or body </li></ul><ul><li>Splenium </li></ul><ul><li>The anterior part divided into outer and inner zone by cingulate sulcus </li></ul>
  17. 17. splenium Body or trunk Genu Rostrum Medial surface with corpus callosum
  18. 18. Cingulate sulcus Parieto-occipital sulcus Calcarine sulcus Collateral sulcus Sulcus in the medial surface
  19. 19. Sulcus and gyrus………contd. <ul><li>The posterior region of the medial surface is traversed by parieto-occipital and calcarine sulcus .The parieto-occipital sulcus marks the boundary between parietal and occipital lobes. </li></ul><ul><li>The visual cortex lies above and below the calcarine sulcus. </li></ul><ul><li>In the inferior cerebral surface </li></ul><ul><li>Olfactory sulcus </li></ul><ul><li>Rhinal sulcus </li></ul><ul><li>Occipitotemporal sulcus </li></ul><ul><li>Collateral sulcus </li></ul>
  20. 20. Orbital sulcus Occipitotemporal sulcus Collateral sulcus Rhinal sulcus Sulcus and important structures on inferior surface of cerebral hemisphere Olfactory sulcus
  21. 21. Insula -Present within the lateral sulcus Between temporal and frontal Lobe. -The overlying cortical areas are called opercula formed from the parts of frontal,temporal and parietal lobe -Functions linked to emotion and body’s homeostasis -i.e perception,motor control,self awarness,congnitive functioning interpersonal experience Insula
  22. 22. Cerebral cortex <ul><li>Cerebral cortex is an intricate blend of nerve cells and fibres,neuroglia and blood vessels. </li></ul><ul><li>Microscopically the cortex consists of six layers or laminae lying parallel to the surface. </li></ul><ul><li>From outside to inside </li></ul><ul><li>Molecular or plexiform layer </li></ul><ul><li>The external granular layer </li></ul><ul><li>External pyramidal lamina </li></ul><ul><li>Internal granular layer </li></ul><ul><li>Internal pyramidal cell layer </li></ul><ul><li>Multiform or pleiomorphic layer </li></ul>
  23. 23. Pyramidal cells
  24. 24. Neocortex has 6 layers designated I, II, III, IV, V, VI Pyramidal cells predominate in layers III and V Granule cells in layers II and IV Pyramidal cells Granule cells Cerebral cortex
  25. 25. <ul><li>Pyramidal cells have large apical dendrite and basal dendrites </li></ul><ul><li>Axon projects downward into subcortical white matter; may have collaterals </li></ul><ul><li>Pyramidal cell is the primary output neuron </li></ul>Pyramidal cell
  26. 26. Pyramidal cell Pyramidal cell
  27. 27. Broadmann’s areas <ul><li>These areas were defined and numbered by korbinian broadmann </li></ul><ul><li>The areas are based on the cortical cytoarchitectonic organisation of neurons </li></ul><ul><li>Many of the broadmann’s areas are defined on neurological function coorelated closely to diverse cortical functions. </li></ul><ul><li>For example </li></ul><ul><li>Area 1,2,3 – primary somatosensory area </li></ul><ul><li>Area 4 – Motor area </li></ul><ul><li>Area 41,42 – Auditory area </li></ul><ul><li>Area 44,45 – Broca’s area,etc </li></ul>
  28. 28. Mapping of sensory and motor areas to the body
  29. 29. <ul><li>Primary Motor Cortex ( Precentral Gyrus) – Cortical site involved with controlling movements of the body. </li></ul><ul><li>Broca’s Area – Controls facial neurons, speech, and language comprehension. Located on Left Frontal Lobe. </li></ul>Broca’s Aphasia – Results in the ability to comprehend speech, but the decreased motor ability (or inability) to speak and form words. Orbitofrontal Cortex – Site of Frontal Lobotomies <ul><ul><li>* Desired Effects: </li></ul></ul><ul><ul><ul><li>- Diminished Rage </li></ul></ul></ul><ul><ul><ul><li>- Decreased Aggression </li></ul></ul></ul><ul><ul><ul><li>- Poor Emotional Responses </li></ul></ul></ul>* Possible Side Effects: - Epilepsy - Poor Emotional Responses - Perseveration (Uncontrolled, repetitive actions, gestures, or words) Frontal lobes cortical regions Primary motor cortex Broca’s area Orbitofrontal cortex
  30. 30. <ul><li>Primary Somatosensory Cortex (Postcentral Gyrus) – Site involved with processing of tactile and proprioceptive information. </li></ul><ul><li>Somatosensory Association Cortex - Assists with the integration and interpretation of sensations relative to body position and orientation in space. May assist with visuo-motor coordination </li></ul><ul><li>Primary Gustatory Cortex – Primary site involved with the interpretation of the sensation of Taste. </li></ul>Parietal lobe cortical areas Associated somatosensory area(7) Primary gustatory area (40) Primary somatosensory area (3, 1, 2)
  31. 31. Primary Visual Cortex – This is the primary area of the brain responsible for sight -recognition of size, color, light, motion, dimensions, etc. Visual Association Area – Interprets information acquired through the primary visual cortex. Occipital lobe and cortical regions
  32. 32. White matter of cerebrum <ul><li>Consists of myelinated nerve fibres which are categorized on the basis of their course and connections </li></ul><ul><li>Association fibres </li></ul><ul><li>It links different cortical areas of the same hemisphere </li></ul><ul><li>Two types </li></ul><ul><li>Short association fibres </li></ul><ul><li>They are entirely intracotical </li></ul><ul><li>Some merely pass from one wall of the sulcus to othe r. </li></ul><ul><li>Long association fibres </li></ul><ul><li>They are present in bundles </li></ul><ul><li>Example: uncinate fasciculus,cingulum,superior longitudinal fasciculus,etc </li></ul>
  33. 33. White matter of cerebrum………contd. <ul><li>Commissural(transverse) fibres </li></ul><ul><li>Commisural fibres cross the midline,linking corresponding areas in the two cerebral hemisphere. </li></ul><ul><li>The largest commissure is the corpus callosum . Other commisures are </li></ul><ul><li>Anterior </li></ul><ul><li>Posterior </li></ul><ul><li>Habenular </li></ul><ul><li>Commissure of the fornix . </li></ul>
  34. 34. White matter of cerebrum……..contd. <ul><li>Projection fibres </li></ul><ul><li>Projection fibres connect cerebral cortex with lower levels in the brain and spinal cord. </li></ul><ul><li>Consists of both coticofugal and corticopetal fibres </li></ul><ul><li>Corticofugal fibres converge from all directions to form corona radiata.Corona radiata continous with the internal capsule. </li></ul>
  35. 35. Corpus callosum Anterior commissure Habenular commissure Posterior commissure Commissures of brain Commissure of fornix
  37. 37. CT scan of the brain showing a tumour in the right cerebral hemisphere CT scan of brain…….contd
  38. 38. MRI OF BRAIN
  39. 39. . A non-progressive disorder • Caused by brain injury pre (70-80%), peri, or post natally • Injure occurs before CNS reaches maturity • Patients often have great potential masked by their connections Cerebral palsy • Malfunction of motor centers • Postural and balance difficulties • Normal life expectancy possible • Early death respiratory Manifestation
  40. 40. Spastic • 52-70% of all CPs • Hyperirritability of muscles • Arms flexed, legs internally rotated • Difficulty bending into a sitting position • Difficulty with head control • Postural difficulty • May not have protective extension Athetoid or Dyskinetic Type <ul><li>• 25- 30% of CPs </li></ul><ul><li>• Uncontrollable writhing movements of </li></ul><ul><li>opposing muscle groups </li></ul><ul><li>• All four extremities involved </li></ul><ul><li>• Neck and face involved </li></ul><ul><li>• Voluntary movements are flailing </li></ul><ul><li>• Difficulty uprighting and balancing </li></ul><ul><li>Grimacing </li></ul>
  41. 41. • Tremors (rare form) of CP • Rigid 5 -10% of CPs • Flaccid (Hypotonicity) • Mixed 15 - 40% of CPs • 5 to 10 % • Affects balance and coordination. • They may walk with an unsteady gait with feet far apart, and they have difficulty with motions that require precise coordination, such as writing. Ataxic cerebral palsy Other types
  43. 43. SKULL BASE Skull base boundaries : Upper surface of the ethmoid bone,orbital plate of the frontal bone upto the ethmoid bo ne <ul><li>Key bones: </li></ul><ul><li>Orbital Plate of frontal bone </li></ul><ul><li>Ethmoid bone </li></ul><ul><li>Sphenoid bone </li></ul><ul><li>Occipital bone </li></ul>
  44. 44. Skull base……contd. Divided into three cranial fossa: a. Anterior cranial fossa b. Middle cranial fossa c. Posterior cranial fossa
  45. 45. Key openings in base of the skull <ul><li>Foramen spinosum </li></ul><ul><li>Foramen ovale </li></ul><ul><li>Foramen lacerum </li></ul><ul><li>Foramen rotundum </li></ul><ul><li>Foramen magnum </li></ul><ul><li>Jugular foramen </li></ul><ul><li>Superior orbital fissure </li></ul><ul><li>Inferior orbital fissure </li></ul><ul><li>Optic canal </li></ul><ul><li>Hypoglossal canal </li></ul><ul><li>Pterygopalatine fossa </li></ul>Skull base……contd.
  46. 46. <ul><li>Foramen rotundum </li></ul><ul><li>Present at the anterior and medial part of sphenoid bone. </li></ul><ul><li>Structures passing </li></ul><ul><li>Maxillary nerve </li></ul><ul><li>Emissary veins </li></ul>
  47. 47. <ul><li>Foramen ovale </li></ul><ul><li>Located in the anterior part of sphenoid bone,posterolateral to foramen rotundum </li></ul><ul><li>Structures passing </li></ul><ul><li>Mandibular nerve </li></ul><ul><li>Accessory meningeal artey </li></ul><ul><li>Lesser petrosal nerve </li></ul><ul><li>Emissary veins </li></ul>
  48. 48. <ul><li>Foramen spinosum </li></ul><ul><li>Foramen spinosum may be absent in 2% of the cases. </li></ul><ul><li>Situated posterolateral to foramen ovale </li></ul><ul><li>Transmits following structures </li></ul><ul><li>Middle meningeal artery </li></ul><ul><li>Nervous spinosus from mandibular nerve </li></ul><ul><li>Middle meninigeal vein </li></ul>
  49. 49. <ul><li>Foramen magnum </li></ul><ul><li>Latin ”great hole” is present in the occipital bone </li></ul><ul><li>It transmits </li></ul><ul><li>Medulla oblongata,vertebral arteries </li></ul><ul><li>Anterior and Posterior spinal arteries </li></ul><ul><li>Spinal accessory nerve </li></ul><ul><li>Membrana tectoria,Alar ligaments. </li></ul>
  50. 50. <ul><li>Superior Orbital Fissure </li></ul><ul><li>CN III, IV, V 1 , VI </li></ul><ul><li>Middle meningeal artery- orbital branch </li></ul><ul><li>Recurrent meningeal artery </li></ul><ul><li>Superior opthalmic vein </li></ul><ul><li>Jugular foramen </li></ul><ul><li>Anterior compartment </li></ul><ul><li>Inferior petrosal sinus </li></ul><ul><li>intermediate compartment </li></ul><ul><li>Cranial nerve IX,X,XI </li></ul><ul><li>Posterior compartment </li></ul><ul><li>Internal jogular vein </li></ul><ul><li>Meningeal branches of occipital and ascending pharyngeal artery </li></ul>
  51. 51. THANK YOU