PARIETAL LOBE BOUNDARY 5 January 2011A. Lateral surface 1. Anterior - Central sulcus Parietal lobe 2. Inferio-Posterior – sylvian fissure. No sharp boundaries,merges with temporal & occipital lobeB. Medial sufface 1. Posterior – parietooccipital sulci to line extending down to the preoccipital notch on the inferior border
PARIETAL LOBE SULCI AND GYRI Post central sulcus – posterior boundary of somatosensory cortex. Interparietal sulcus behind post central sulcus which divides the parietal lobe into sup. & inf. Parietal lobule Posterior end of sylvian fissure curves upwards to terminates into inf.parietal lobule – surrounding cortex supramarginal gyrus[SMG 40] 5 January 2011 Parietal lobe
PARIETAL LOBE SULCI AND GYRI Posterior end of sup. Temporal sulcus – angular gyrus[AG 39] SMG & AG = Ecker’s Iinf Parietal Lobule Ecker’s IPL & post. Third of first temporal gyrus constitute the wernicke’language area 3,1,2-primary sensory areas 5- somatosensory association area 7-somatosensory or somatosensory/visual 5 January 2011 Parietal lobe
ANATOMY 5 January 2011 Histology Development Post central gyrus – Sup and inf. Parietal Parietal lobe homotypical granular lobule and adjacent cortex temporal occipital lobe Rest – association larger in human than cortex primate develops 6-7 years of age
PARTIAL LOBE CONNECTIONS 5 January 2011 Affrents Effrents Post central gyrus Somatosensory cortex - Parietal lobe VP thalamic nuclei > area 5 superior Spindle affrent -> 3a parietal lobule Cutaneous affrent -> 3b +1 1,3,5 (except hand and Joint affrent -> 2 foot area) -> opp. Association cortex somatosensory cortex To frontal, temporal and occipital cortex of both side
ELECTRICAL STIMULATION 5 January 2011 Somatosensory cortex Parietal lobe Numb tingling sensation and sense of movements , rarely pain warmth and cold Sup and Inf. parietal lobule No sensory or motor response (silent area)
FUNCTIONS Ant. Parietal cortex- tactile perception Post.secondary sensory area- tactile discrimination,position, t. localization, stereognosis, graphaesthesia Spatial orientation Constructional activity Language - Understanding the grammatical & syntactical aspects of language Arithmetic, calculation 5 January 2011 Parietal lobe
POST CENTRAL GYRUS 5 January 20111. Eyes closed - patient is to 7. Height discrimination position hand to match 8. Pinpoint vs. head. Parietal lobe position of other. 9. Touch area on skin, have2. Passive finger detection. patient point to area on3. Two point threshold. contralateral side.4. Von Frey Hair threshold. 10. Fasten a button.5. Vibration sense. 11. Tie a shoelace.6. With lesion most severe 12. Localized lesion by deficit changes are distal, interactions. coarse sensations return first
POST CENTRAL GYRUS TESTS 5 January 20111. Eyes closed - match one 7. Touch area and have hand to position set by patient point to examiner. contralateral area Parietal lobe2. Passive finger detection 8. Fine motor tasks two point threshold 9. unusual speech. two point finger test Consonant substitutions (especially of similar matchbox test sounds), without broken finger-tip number writing. or jerky speech typical of4. Vibration sense - tuning Brocas Aphasia. May see fork writing errors due to role5. Weight discrimination. of articulatory movements in analysis of words.6. Pinpoint vs. head - use a pin.
INFERIOR PARIETAL LOBULE 5 January 20111. Apraxia for dressing. 7. Difficulty in performing reversible operations in2. Constructional apraxia (spatial extrapersonal space (difficulty Parietal lobe apraxagnosia) - problems in in taking different perspectives) motor integration in (more severe for right constructional tasks. hemisphere lesions than left).3. Spatial orientation deficit (more 8. Inability to maintain visual severe for right hemisphere image of patterned and verbal lesions than left:). material.4. Right-left disorientation. 9. Visuographic defects. 10. Unilateral neglect.5. Planto-pokinesia (disorganization of discriminations in spatial 11. General intellectual impairment Judgment). (lesions in left hemisphere). 12. Problems with writing and6. Visuospatial agnosia. defective comprehension in reading.
IPL ASSESSMENT 5 January 2011 1. Inability to analyze positions of 9. Difficulty designating body hands on a clock. parts on examiner. 2. Confuses symmetrically 10. Difficulty drawing common arranged symbols (e.g., d & b). objects to demand. Parietal lobe 3. Difficulty making rotations on a 11. Problems in visual memory 2-D stick test. for patterns and verbal matter. 4. Difficulty changing 12. Errors on the Bender. perspectives on a village scene 13. Poor performance on test. Unknown Faces Test 5. Difficulty with transformations 14. Difficulty with simple addition, on pool reflections test. subtraction, multiplication, and 6. Problems on both visual and division, both presented orally tactile route finding tests. and written. 7. Difficulty in maze learning. 15. WAIS arithmetic subtest 8. Inability to follow habitual scores lowered. routes. 16. Low test scores on Army General Classification Test.
SUPRAMARGINAL GYRUS 5 January 2011Ideomotor apraxia: Conduction aphasia: disruption of results from left organization of hemisphere lesion if the Parietal lobe underlying arcuate complex acts fasciculus is cut Results from left Severely defective hemisphere lesion repetition Usually affects both Paraphasia in sides, may be worse on repetition and in right side spontaneous speech Can affect the face Normal (buccofacial) and/or the comprehension limbs Impaired writing, spontaneous and to dictation, errors in spelling, word choice, syntax
SUPRAMARGINAL GYRUS 5 January 20111. Astereognosis: 1. Finger agnosia: impairment of inability to recognize, somatosensory name, and point to Parietal lobe discrimination individual fingers on Left hemisphere self and others (left lesion: both hands hemisphere lesion). affected 2. Right-left Right hemisphere disorientation lesion: deficit - left Cant distinguish right hand from left on self or env. More common with left hemisphere lesion
SUPRAMARGINAL GYRUS (SMG) 5 January 20111. Acalculia 1. Gerstmanns Loss of ability to syndrome: : Right-left Parietal lobe understand & order numbers disorientation More severe with left Finger agnosia hemisphere lesion Agraphia Acalculia2. Tactile perceptual disability: results from 2. Right hemisphere Constructional apraxia contralateral lesion Mild left side neglect and/or denial Inability to interpret maps
TESTS FOR SMG 5 January 2011Ideomotor apraxia Conduction aphasia Carrying out motor Repetition of words, acts to command: phrases, & sentences Parietal lobe buccofacial (blow out Write to dictation a match, protrude (letters, words, tongue, drink through sentences) a straw) Ask patient to write Carrying out motor sentences describing acts to command: limb a Job, the weather, or (salute, use a a picture toothbrush, flip a Confrontation naming coin, hammer a of objects, clothing, nail, comb hair, snap body parts, parts of fingers, kick a objects ball, crush out a cigarette)
TESTS FOR SMG 5 January 2011Astereognosis (with eyes Finger agnosia closed) In-between test, Two- Patient identifies by Parietal lobe Point Finger Test, touch such common and Match Box Test objects as a coin, paperclip, pencil, or Identifying named key (each hand tested fingers on examiners separately) hands and naming Patient judges the fingers on self relative size of a series of coins Patient judges the texture of a series of objects, such as cloth, wire, sandpaper
TEST FOR SMG 5 January 2011Right-left disorientation Gerstmanns syndrome Identification of right Right-left and left limbs on self disorientation Parietal lobe and examiner Finger agnosia Crossed commands Agraphia: writing to on self and examiner dictation and writingAcalculia sentences describing Written scenes in pictures addition, subtraction, Acalculia multiplication, and division problems Verbal complex problemsFingertip number writing
TEST FOR LEFT SMG 5 January 2011 Constructional drawing to command: apraxia clock, bicycle, flower in Parietal lobe copying designs pot match stick tests behavioral observations block construction test Have patient locate cities on a map Left-side neglect glove test: ask the patient to put on a pair of gloves
ANGULAR GYRUS FUNCTION 5 January 20111. Tertiary in function: lies at the boundary between the occipital, temporal, and postcentral regions of the hemisphere, where the cortical areas for visual, auditory, vestibular, cutaneous, and proprioceptive sensations overlap. Parietal lobe2. Supramodal in function: plays a special role in inter-analyzer syntheses. The angular gyrus, as part of the inferior parietal lobule, is the association area of association areas and allows cross modal transfer and associations between either vision or touch and hearing . As the angular gyrus is important in the processing of associating a heard name to a seen or felt object, it is probably also important for associations in the reverse direction. A "name" passes through Wernickes area, then via the angular gyrus arouses associations in the other parts of the brain. Thus, the angular gyrus acts as a way station between the primary sensory modalities and the speech area.3. The development of language is probably heavily dependent on this area. Object naming, one of the simplest aspects of language, depends on associations between other modalities and audition.4. Association cortex that combines visual and auditory information necessary for reading and writing. Designed for storing the memory of the "rules of translation" from written to spoken language.
ANGULAR GYRUS – BEHAVIORAL DEFICIT 5 January 2011 Alexia without agraphia: results when the inferior parietal lobule is disconnected from all visual input. Pure word blindness results due to a disconnexion from the "memory centre". • Reading aloud and comprehension of written words is lost. • Ability to name and recognize objects is preserved. Objects have rich, multiple associations in other areas, e.g. one can recognize an apple by vision, touch, taste, smell, even by texture. The arousal of such associations permits the finding Parietal lobe of an alternative pathway across an uninvolved more anterior portion of the corpus callosum. • Persistent difficulty in color naming but can match colors by hue without error. • Loss of ability to read music. • Spelling and spelling comprehension way he quite normal • Writing should be normal or nearly so; however, subtle defects can usually present (e.g. letters are too large or too widely spaced, there may be an absence or misuse of punctuation, capitals may be disregarded, letters dropped or reduplicated). • This syndrome is referred to as agnostic alexia by Brown. He states that a right hemanopia is an almost constant. Alexia with agraphia: results from damage to the angular gyrus itself and renders the patient unable to read and write. May be referred to as aqraphic alexia or angular gyrus alexia. • A loss of visual word memory returns the patient to the state of being illiterate; lack of reading, writing, and spelling, and an incomprehension of spelled words are all components of this more primitive state. • Reading has a global character, without facilitation by literal analysis or letter tracing. Paralexia is present in reading aloud, especially for letters. • Letters are misnamed and patients cannot Indicate or sort letters accurately to command, unless first given a visual model of the letter tested, nor can they select the correct letter name from a spoken group. Patients are unable to match spoken letter sounds to written letters. • There is an inability to spell all but the simplest words, either to command or to a presented object. • Printing is variable, but always impaired. The agraphia reflects the spelling deficiency, as well as, in severe cases, the loss of conceptualization of words as whole units. Although specific assessment devices have not been mentioned, it would appear that qualitative analysis of reading, writing, and spelling abilities is warranted in assessing the above syndromes.
PARIETO-TEMPORAL-OCCIPITAL CORTEX This area is a tertiary, general sensory association area that integrates 5 January 2011 visual, tactile, and auditory information. A. Lesions of this area will produce complex disorders that may include: Constructional Apraxia: defects in copying designs and in drawing to command. • Left hemisphere lesions: ordering of movements is disrupted, simplification of Parietal lobe drawings, difficulty making angles. • Right hemisphere lesions: more severe deficits such as visuo-spatial defects, neglect of left side of drawing, disproportions. Difficulties in serial ordering: comprehension of order and sequence. • Left hemisphere lesions: disruption of sequential organization of speech. • Right hemisphere lesions: cannot understand temporal relationships and is unable to make future plans. Visual memory disturbance: defective revisualization • Left hemisphere lesions: inability to evoke visual image in response to a given word. • Right hemisphere lesions: inability to retain visual image of nonverbal, spatial figures. Impaired recognition and comprehension of complex, symbolic stimuli. • Left hemisphere lesions only • Symptoms of aphasia may also be seen.
TESTS FOR PARIETO-TEMPORO-OCCIPITALAREA 5 January 2011 Constructional apraxia • Copying designs: diamond, cross, cube, pipe. • Drawing to command: clock, daisy in flowerpot, house in perspective. Parietal lobe • Match stick pattern test. • Block construction test. Difficulties in serial ordering • Observations of spontaneous speech • Ability to order events in time: both life history events and objective events such as the Presidential terms . Visual memory disturbance • Left hemisphere: Ask patient to describe objects that are not present • Right hemisphere: Short-term visual memory for geometric patterns Impaired comprehension of complex symbolic stimuli • Ask patient to explain complex logico-gram-matical constructions such as "brothers father" • Give commands such as "draw a circle under a square"
CLINICAL SYNDROMES 5 January 2011 Either hemisphere 1. Cortical sensory syndrome& sensory extinction Total hemi anesthesia with large acute lesion of Parietal lobe 2. white matter 3. Mild hemi paresis, unilateral muscular atrophy in children, hypotonia, poverty of movements, hemiataxia 4. Homonymous hemianopia [incongruent or congruent], visual inattention sometime anosognosia, neglect of one half of body and extrapersonal space (with right than left lesion) 5. Abolition of optokinetic nystagmus with target moving towards the side of lesion
RIGHT HEMISPHERE 5 January 2011 1. Topographic disorientation Parietal lobe 2. Topographic memory loss 3. Anosognosia /dressing apraxia 4. Constructional apraxia 5. Hemi-inattention 6. Apraxia of eye opening 7. Confusion