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Cortical areas of brain

Cortical areas of brain by Brodmann

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Cortical areas of brain

  1. 1. DR PRATIK MISTRY
  2. 2.  Allocortex – 10 % (also called Limbic Cortex) i. Archipallium – hippocampus & Dentate gyrus. ii. Paleopallium – Uncus & part of Parahippocampal gyrus. iii. Mesocortex. – transitional zone.  Neocortex (Isocortex) -Rest of 90% of cerebral cortex.
  3. 3.  Six layers 1. Molecular 2. Outer granular 3. Outer pyramidal 4. Inner granular 5. Inner pyramidal 6. Pleomorphic  Cells: 1. Pyramidal cells of betz 2. Granule (stelate) cells 3. Cells of martinoti 4. Horizontal cells of cajal
  4. 4.  AGRANULAR CORTEX  Pyramidal cells – large, Betz cells  Granule cells absent or less in number  Seen in Motor cortex (4) & Boca's motor speech area (44)  GRANULAR CORTEX  Excess granule cells  Few pyramidal cells  Seen in sensory cortex & visual area, auditory area
  5. 5.  FRONTAL CORTEX  Small and medium pyramidal cells  Few stellate cells  Pre-frontal cortex of frontal lobe  PARIETAL CORTEX  More stellate cells  Seen in most of parietal lobe & junction of parietal, temporal & occipital lobes  POLAR CORTEX  Thinnest of all  All layers reduced depth.  Seen in frontal & occipital pole
  6. 6.  For functional analysis, cerebral cortex is divided into number areas, 20 areas of Campbell 109 areas of Economo 200 areas of Vogt 52 areas of brodmann- frequently used  Subdivided into motor, sensory and association areas
  7. 7.  Subdivided into  Primary motor area (area 4)  Pre-motor area (area 6)  Frontal eye field (area 8)  Supplementary motor area  Pre-frontal area (areas 9 to 12)
  8. 8. Location:  Precentral gyrus (area 4)  Extends to the ant. part of paracentral lobule  Agranular cortex Afferents :  Premotor area (Area 6)  Somesthetic or somatosensory cortex  Ant. Part ventral nucleus of thalamus(which receives info. from cerebellum  Basal ganglia
  9. 9. Efferents :  Fibres from area 4 and area 6 forming… 1. Corticospinal 2. Corticonuclear 3. Corticobulbar tracts.  Regulate the voluntary movements of opposite side of body  Fronto-pontine fibres  Corpus striatum, red nucleus
  10. 10.  Control movements of voluntary muscles of opposite side  Movements represented with head end below and leg end up (INVERTED MOTOR HOMUNCULUS)  Centres from below are: lips, tongue, larynx, pharynx, face, head & neck, upper limb with large area for fingers and hand, trunk, lower limb above knee.  Ant. Part of paracentral lobule  Extent of area depend on skill of movement and not on the bulk of muscle
  11. 11.  Somewhat sensory. Receive some sensations like tingling and numbness  Known as MSI  Muscles of forehead, tongue, mastication, larynx, pharynx, extra ocular bilaterally represented  Only movements not muscles  LESION: initially flaccid paralysis
  12. 12. Location (area 6):  In front of area 4, include post. Part of sup., middle and inf. Frontal gyri  On medial side, continue with supplementary motor area  Agranular & motor
  13. 13.  Integrates voluntary movements to perform skilful act.  Writing centre  Concerned with programming which is executed by area 4 LESION:  Produce difficulty in the performance of skilled movements.  Apraxia: loss of the ability to do simple or routine acts in the absence of paralysis.  Agraphia: when writing is also involved.
  14. 14. PRIMARY SOMATOMOTOR AREA (MSI) = PRIMARY MOTOR AREA PREMOTOR AREA
  15. 15.  Lie in front of area 6  Involve posterior part of middle frontal gyrus  Agranular cortex  Regulate voluntary conjugate movements of eye. Deviation of eyes to the opposite side  Controls voluntary scanning movements of the eyes and is independent of the visual stimuli.  Connected to the visual area of occipital cortex by association fibres.  Lesion of the area cause two eye to deviate to the side of lesion
  16. 16.  Located on medial surface of cerebrum in the post. part of medial frontal gyrus anterior to the paracentral lobule  Afferents from VA and VL of thalamus  Efferents to area 4  Function is to control complex movements. Produce sensation of “URGE TO MOVE’  Receive some senses (MSII)  Lesion of area produce AKINESIA
  17. 17.  Rest of frontal lobe ant. to pre-motor area which include orbital surface also  Fibres from thalamus, hypothalamus, limbic system, all areas of cortex  Concerned with individual’s personality  Regulate depth of feeling, thinking, mature judgement, orientation, concentration, pleasure and displeasure, right or wrong.  Bilateral damage due to trauma or tumour: change in personality, loss of concentration, judgement, inappropriate social behaviour like vulgarity of speech, improper clothing
  18. 18. Primary Secondary Sensory Association Somesthetic (sensory) Visual Auditory
  19. 19.  Primary somesthetic areas (areas 3,1,2)  Secondary somesthetic area  Somesthetic association are (areas 5,7)
  20. 20.  Located in the post-central gyrus and extends into the posterior part of the paracentral lobule on the medial surface.  Granular cortex  Afferents from VPL and VPM of thalamus and other areas of cortex
  21. 21.  Localise, analyse, discriminate all modalities of sensations  Sensations represented with head end below (INVERTED SENSORY HOMUNCULUS)  Paracentral lobule receive sense of distension from bladder and rectum  Hand, face, tongue, lips having larger representation in cortex  Lower part act as taste centre (area 43)  Modulate sensory input  Secondarily motor (SMI)
  22. 22.  Located on the posterior part of posterior ramus of lateral sulcus  Involve lower part of pre and post-central gyri  Receive mainly pain sensation  Somewhat motor in function (SMII)
  23. 23.  Located in the superior parietal lobule  Connected with higher association area in supra- marginal gyrus (area 40)  Concerned with the perception of shape, size, roughness, and texture of the objects  Stereognosis- ability to identify known objects in hand with closed eyes  Astereognosis or Tactile agnosia
  24. 24.  Primary visual area (area 17)  Visual association area (area 18 & 19)  Higher visual association area (area 39)
  25. 25.  Located in the lips and walls of posterior part of calcarine sulcus which include cuneus and lingual gyrus  Thinner and granular cortex  Stria of gennari  Afferents from optic radiation  Temporal half of same retina and nasal half of opposite retina  Register opposite field of vision
  26. 26. Macular area-  occupying approximately posterior one-third of the visual cortex.  is the central area of retina and responsible for maximum visual acuity (keenest vision) has extensive cortical representation  Connected to area 18, 19 of both sides  Concerned with reception and perception of simple visual impressions like colour, size, form, transparency etc.
  27. 27.  Unilateral lesion due to thrombosis, trauma produce partial blindness (hemianopia) with macular vision retained  Macular sparing because it is supplied by both MCA and PCA
  28. 28.  Occupy rest of occipital lobe and calcarine sulcus  Afferents from area 17  Occipital eye field- produce involuntary deviation of eyes reflexly
  29. 29.  Located in the angular gyrus of inferior parietal lobule  It relate visual information to the past experience, thus enabling person to recognize and identify the object by vision  Lesion of this area- visual agnosia- inability to recognize known objects by vision  Sensory aphasia (word blindness)- inability to recognize written word
  30. 30.  Primary auditory area (area 41)  Auditory association area (area 42)  Higher auditory association area (Wernicke's area) (area 22)
  31. 31.  Involve anterior transverse temporal gyrus (of Heschl), on the upper part of sup. temporal gyrus  Granular cortex  Afferents from MGB as auditory radiation  Detect the changes in frequency and direction from where sound originates  Unilateral lesion no deafness due to bilateral presentation
  32. 32.  Lie behind area 41  Involve posterior transverse temporal gyrus of superior temporal gyrus  Granular cortex  Same function
  33. 33.  Wernicke’s area  Rest of the area  Afferents from area 41 & 42  Interpretation of sounds and comprehension of spoken language from past auditory experiences  Lesion produce sensory aphasia (word deafness)- unable to interpret the spoken words.
  34. 34.  Taste area (area 43)- lower part of inf. parietal lobule  Vestibular area- lower part post-central gyrus near face area  Olfactory area (area 28)- anterior part of parahippocampus gyrus and uncus
  35. 35.  Speech- highly complex function  Speech function performed by dominant hemisphere  In 90%, left one, DOMINANT (TALKING BRAIN) & right one, NON DOMINANT (MUTE BRAIN)  FOUR SPEECH CENTRES: 3 sensory & 1 motor  Sensory speech areas: 1. Area 22 (Wernicke's area) 2. Area 39 3. Area 40  Broca’s motor speech area (area 44 & 45)
  36. 36.  Area 22 (Wernicke’s area)  Interpret spoken language & recognize familiar words  Congenital deaf child- dumb  Area 39 of angular gyrus- store visual images and recognize them by sight  Area 40 of supramarginal gyrus- recognize familiar objects by touch and proprioception  All these 3 areas receive input from hearing, vision, touch and process it in the area 22 &  Then project it to Broca’s area through ARCUATE FASCICULUS
  37. 37.  Located in the pars triangularis and pars posterior of inferior frontal gyrus  Afferents from area 22  Efferents to the muscles of tongue, lips, larynx, pharynx, palate, face for production of speech
  38. 38.  Area 22- word deafness- unable to interpret spoken words. Speak fluently with incorrect and useless words  Area 39- word blindness- inability to recognize written words even written by self  Alexia, Agraphia  Area 40- Astereognosis  Area 44 & 45- motor aphasia- cannot speak properly although he understand everything. Slow speech with many grammatical mistakes  Conduction aphasia- arcuate fasciculus damage

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