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  • 1. CEREBRUM AND BASE OF THE SKULL BY DR MANAH CHANDRA CHANGMAI IMS
  • 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. INTRODUCTION
    • The cerebrum is the largest part of the brain with two hemisphere.The two cerebral hemisphere are linked by commisural fibres of corpus callosum.
    • Each cerebral hemisphere contains externally highly convulated cortex of grey matter and internal mass of white matter or medulla .
    • Each cerebral hemisphere contains lateral venticle continous with the third ventricle through interventricular foramen.
    • The cerebral hemispheres contains motor and sensory areas and the limbic system.
    • Each cerebral cortex is often divided phylogenetically into old allocortex,consisting of archicortex and paleocortex and a newer neocortex.
  • 4. Longitudinal Fissure Cerebral hemisphere
  • 5. Cortex and medulla
  • 6. Surfaces of cerebral hemisphere
    • Each cerebral hemisphere has three surfaces
    • Superolateral surface
    • Medial surface
    • Inferior surface .
    • Inferior surface further divided into two
    • Orbital surface
    • Tentorial surface
  • 7. Surfaces of cerebral hemisphere………contd.
    • Superolateral surface
    • It follows the concavity of the cranial vault
    • Medial surface
    • It is flat and vertical and seperated from its fellow by the great longitudinal fissure and falx cerebri.
    • Inferior surface
    • Inferior surface or the basal surface is irregular and divided into orbital and tentorial surface.
  • 8. Superolateral Medial surface Surfaces of the brain
  • 9. Inferior surface Orbital surface Tentorial surface
  • 10. Borders of cerebral hemisphere Superomedial border Inferior border
  • 11. Occipital pole Frontal pole Temporal pole Poles of the brain
  • 12. Lobes of the brain
    • Four lobes are present
    • Frontal
    • Parietal
    • Occipital
    • Temporal
    • Occasionally insula is considered as the fifth lobe
  • 13. Gyrus and sulcuses
    • Each cerebral hemisphere shows a complex pattern of convulation called Gyrus
    • The gyruses are separated by furrows of varying length called Sulci.
    • The convulated structure increases the cortical volume to three times what it would be if the surface is smooth.
    • The area of the cerebral cortex is 2200cm²
    Sulci (Groove) Fissure (Deep groove) Gyri (Elevation)
  • 14. Important sulci and gyri
    • In the suprolateral surface:
    • Lateral sulcus
    • Deep cleft on the lateral and inferior surface
    • It has a stem which divides into three rami:anterior,ascending,p-osterior.
    • The floor of the posterior ramus is the insula which is hidden cortex.
    Lateral sulcus Central sulcus
  • 15. Important sulcus and gyrus…….contd .
    • ii. The central sulcus
    • It is the boundary between frontal and parietal lobes
    • 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.
    • It demarcates the motor and sensory area of the cerebral cortex.
    • iii. The other known sulcuses are
    • superior frontal sulcus
    • Inferior frontal sulcus
    • Precentral sulcus
    • Postcentral sulcus
  • 16. Medial surface
    • In the medial surface
    • The commisural fibres of the corpus callosum lies in the depth of longitudinal fissure
    • Parts of corpus callosum
    • Rostrum
    • Genu
    • Trunk or body
    • Splenium
    • The anterior part divided into outer and inner zone by cingulate sulcus
  • 17. splenium Body or trunk Genu Rostrum Medial surface with corpus callosum
  • 18. Cingulate sulcus Parieto-occipital sulcus Calcarine sulcus Collateral sulcus Sulcus in the medial surface
  • 19. Sulcus and gyrus………contd.
    • 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.
    • The visual cortex lies above and below the calcarine sulcus.
    • In the inferior cerebral surface
    • Olfactory sulcus
    • Rhinal sulcus
    • Occipitotemporal sulcus
    • Collateral sulcus
  • 20. Orbital sulcus Occipitotemporal sulcus Collateral sulcus Rhinal sulcus Sulcus and important structures on inferior surface of cerebral hemisphere Olfactory sulcus
  • 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. Cerebral cortex
    • Cerebral cortex is an intricate blend of nerve cells and fibres,neuroglia and blood vessels.
    • Microscopically the cortex consists of six layers or laminae lying parallel to the surface.
    • From outside to inside
    • Molecular or plexiform layer
    • The external granular layer
    • External pyramidal lamina
    • Internal granular layer
    • Internal pyramidal cell layer
    • Multiform or pleiomorphic layer
  • 23. Pyramidal cells
  • 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.
    • Pyramidal cells have large apical dendrite and basal dendrites
    • Axon projects downward into subcortical white matter; may have collaterals
    • Pyramidal cell is the primary output neuron
    Pyramidal cell
  • 26. Pyramidal cell Pyramidal cell
  • 27. Broadmann’s areas
    • These areas were defined and numbered by korbinian broadmann
    • The areas are based on the cortical cytoarchitectonic organisation of neurons
    • Many of the broadmann’s areas are defined on neurological function coorelated closely to diverse cortical functions.
    • For example
    • Area 1,2,3 – primary somatosensory area
    • Area 4 – Motor area
    • Area 41,42 – Auditory area
    • Area 44,45 – Broca’s area,etc
  • 28. Mapping of sensory and motor areas to the body
  • 29.
    • Primary Motor Cortex ( Precentral Gyrus) – Cortical site involved with controlling movements of the body.
    • Broca’s Area – Controls facial neurons, speech, and language comprehension. Located on Left Frontal Lobe.
    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
      • * Desired Effects:
        • - Diminished Rage
        • - Decreased Aggression
        • - Poor Emotional Responses
    * 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.
    • Primary Somatosensory Cortex (Postcentral Gyrus) – Site involved with processing of tactile and proprioceptive information.
    • 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
    • Primary Gustatory Cortex – Primary site involved with the interpretation of the sensation of Taste.
    Parietal lobe cortical areas Associated somatosensory area(7) Primary gustatory area (40) Primary somatosensory area (3, 1, 2)
  • 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. White matter of cerebrum
    • Consists of myelinated nerve fibres which are categorized on the basis of their course and connections
    • Association fibres
    • It links different cortical areas of the same hemisphere
    • Two types
    • Short association fibres
    • They are entirely intracotical
    • Some merely pass from one wall of the sulcus to othe r.
    • Long association fibres
    • They are present in bundles
    • Example: uncinate fasciculus,cingulum,superior longitudinal fasciculus,etc
  • 33. White matter of cerebrum………contd.
    • Commissural(transverse) fibres
    • Commisural fibres cross the midline,linking corresponding areas in the two cerebral hemisphere.
    • The largest commissure is the corpus callosum . Other commisures are
    • Anterior
    • Posterior
    • Habenular
    • Commissure of the fornix .
  • 34. White matter of cerebrum……..contd.
    • Projection fibres
    • Projection fibres connect cerebral cortex with lower levels in the brain and spinal cord.
    • Consists of both coticofugal and corticopetal fibres
    • Corticofugal fibres converge from all directions to form corona radiata.Corona radiata continous with the internal capsule.
  • 35. Corpus callosum Anterior commissure Habenular commissure Posterior commissure Commissures of brain Commissure of fornix
  • 36. CT SCAN OF THE BRAIN
  • 37. CT scan of the brain showing a tumour in the right cerebral hemisphere CT scan of brain…….contd
  • 38. MRI OF BRAIN
  • 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. 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
    • • 25- 30% of CPs
    • • Uncontrollable writhing movements of
    • opposing muscle groups
    • • All four extremities involved
    • • Neck and face involved
    • • Voluntary movements are flailing
    • • Difficulty uprighting and balancing
    • Grimacing
  • 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
  • 42. BASE OF THE SKULL
  • 43. SKULL BASE Skull base boundaries : Upper surface of the ethmoid bone,orbital plate of the frontal bone upto the ethmoid bo ne
    • Key bones:
    • Orbital Plate of frontal bone
    • Ethmoid bone
    • Sphenoid bone
    • Occipital bone
  • 44. Skull base……contd. Divided into three cranial fossa: a. Anterior cranial fossa b. Middle cranial fossa c. Posterior cranial fossa
  • 45. Key openings in base of the skull
    • Foramen spinosum
    • Foramen ovale
    • Foramen lacerum
    • Foramen rotundum
    • Foramen magnum
    • Jugular foramen
    • Superior orbital fissure
    • Inferior orbital fissure
    • Optic canal
    • Hypoglossal canal
    • Pterygopalatine fossa
    Skull base……contd.
  • 46.
    • Foramen rotundum
    • Present at the anterior and medial part of sphenoid bone.
    • Structures passing
    • Maxillary nerve
    • Emissary veins
  • 47.
    • Foramen ovale
    • Located in the anterior part of sphenoid bone,posterolateral to foramen rotundum
    • Structures passing
    • Mandibular nerve
    • Accessory meningeal artey
    • Lesser petrosal nerve
    • Emissary veins
  • 48.
    • Foramen spinosum
    • Foramen spinosum may be absent in 2% of the cases.
    • Situated posterolateral to foramen ovale
    • Transmits following structures
    • Middle meningeal artery
    • Nervous spinosus from mandibular nerve
    • Middle meninigeal vein
  • 49.
    • Foramen magnum
    • Latin ”great hole” is present in the occipital bone
    • It transmits
    • Medulla oblongata,vertebral arteries
    • Anterior and Posterior spinal arteries
    • Spinal accessory nerve
    • Membrana tectoria,Alar ligaments.
  • 50.
    • Superior Orbital Fissure
    • CN III, IV, V 1 , VI
    • Middle meningeal artery- orbital branch
    • Recurrent meningeal artery
    • Superior opthalmic vein
    • Jugular foramen
    • Anterior compartment
    • Inferior petrosal sinus
    • intermediate compartment
    • Cranial nerve IX,X,XI
    • Posterior compartment
    • Internal jogular vein
    • Meningeal branches of occipital and ascending pharyngeal artery
  • 51. THANK YOU

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