2. PARIETAL LOBE BOUNDARY
5 January 2011
A. Lateral surface
1. Anterior - Central
sulcus
Parietal lobe
2. Inferio-Posterior –
sylvian fissure. No
sharp
boundaries,merges
with temporal &
occipital lobe
B. Medial sufface
1. Posterior –
parietooccipital sulci to
line extending down to
the preoccipital notch
on the inferior border

3. 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

4. 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

5. 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

6. 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

7. 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)

8. 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

9. POST CENTRAL GYRUS
5 January 2011
1. 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, have
2. Passive finger detection. patient point to area on
3. 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

10. POST CENTRAL GYRUS TESTS
5 January 2011
1. Eyes closed - match one 7. Touch area and have
hand to position set by patient point to
examiner. contralateral area
Parietal lobe
2. 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 of
4. Vibration sense - tuning Broca's Aphasia. May see
fork writing errors due to role
5. Weight discrimination. of articulatory movements
in analysis of words.
6. Pinpoint vs. head - use a
pin.

11. INFERIOR PARIETAL LOBULE
5 January 2011
1. Apraxia for dressing. 7. Difficulty in performing
reversible operations in
2. 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 and
6. Visuospatial agnosia. defective comprehension in
reading.

12. 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.

13. SUPRAMARGINAL GYRUS
5 January 2011
Ideomotor 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

14. SUPRAMARGINAL GYRUS
5 January 2011
1. 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  Can't distinguish right
hand from left on self or
env.
 More common with
left hemisphere
lesion

15. SUPRAMARGINAL GYRUS (SMG)
5 January 2011
1. Acalculia 1. Gerstmann's
 Loss of ability to syndrome: :
 Right-left
Parietal lobe
understand & order
numbers disorientation
 More severe with left  Finger agnosia
hemisphere lesion  Agraphia
 Acalculia
2. Tactile perceptual
disability: results from 2. Right hemisphere
 Constructional apraxia
contralateral lesion
 Mild left side neglect
and/or denial
 Inability to interpret
maps

16. TESTS FOR SMG
5 January 2011
Ideomotor 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)

17. TESTS FOR SMG
5 January 2011
Astereognosis (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 examiner's
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

18. TEST FOR SMG
5 January 2011
Right-left disorientation Gerstmann's 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 writing
Acalculia sentences describing
 Written scenes in pictures
addition, subtraction,  Acalculia
multiplication, and
division problems
 Verbal complex
problems
Fingertip number writing

19. 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

20. ANGULAR GYRUS FUNCTION
5 January 2011
1. 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 lobe
2. 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 Wernicke's 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.

21. 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.

22. 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.

23. TESTS FOR PARIETO-TEMPORO-OCCIPITAL
AREA
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
"brother's father"
• Give commands such as "draw a circle under a square"

24. 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

25. 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

26. LEFT HEMISPHERE
5 January 2011
1. Disorder of language
Fluent aphasia, alexia
Parietal lobe

2. Gerstman’s syndrome (Angular
gyrus)
 acalculia,
 finger agnosia,
 left/right disorientation,
 agraphia
3. Tactile agnosia (bimanual
asteriognosis)
4. Bilateral Ideomotor & ideational
apraxia

27. BILATERAL PARIETAL SYNDROME
5 January 2011
 Visual spatial imperceptions
Parietal lobe
 Optic ataxia
 Spatial disorientation
 Simultagnosia
 Visual Agnosia
 Constructional apraxia

28. MISELLANEOUS
5 January 2011
1. Blunted emotionality. apathy.
Parietal lobe
Inattentiveness
2. Confusion, allocheiria
3. Optic ataxia
4. depersonalisation

29. 5 January 2011 Parietal lobe