This document summarizes information about the parietal and occipital lobes of the brain. It discusses the anatomical structures, functions, and clinical effects of lesions to these areas. Key points include that the parietal lobe is involved in somatosensory processing, visual-spatial functions, and language abilities depending on lateralization. Lesions can cause syndromes like neglect or Gerstmann syndrome. The occipital lobe is the visual processing center and lesions can result in visual field deficits or conditions like Balint's syndrome.

1. Presenter :Dr S. Vidya sagar
Moderator : Dr V. Sharbandhraj

2. Over view
 Anatomic& physiological considerations
Boundaries
Sulci &Gyri
Brodmanns area
Blood supply
 Functions
Rightlobe functions
left lobe functions
 Dysfunctions & Syndromes
Either parietal lobe lesions
Dominant &non dominant lesions

4. Sulci &gyri
 2 imp sulci -post central sulcus
- interparietal sulcus
 Post central sulcus –forms the
post. Boundary of the
somesthetic cortex
 Inter parietal sulcus-runs antero
posteriorly from the post central
sulcus
 Inter parietal sulcus separates
the mass of parietal lobe in to
superior & inferior lobules

5. gyri
 Inferior lobule is
composed of the supra
marginal gyrus and
angular gyrus.
 Post central gyrus –
primary somatosensory
cortex-recieves most of
its afferent projections
from the ventro posterior
thalami nucleus.

6. Brodmann Cortical Areas
 Area 3,1,2 –Post central gyrus
(Primary sensory areas)
 Area 5 & 7 –Somato sensory
association areas
 Area 39 – Angular gyrus
 Area 40 – Supra marginal gyrus

7. Blood Supply
 Lateral – MCA
 Artery of Rolandic fissure
 Artery of inter parietal fissure
 Artery of post parietal fissure
 Inter opercular parietal artery
 Artery to angular gyrus
 Mesial - ACA mainly & PCA to a slight extent

8. Venous drainage
 Superficial middle cerebral vein –lies in lateral fissure
 Vein of Trolard (superior anastomotic vein) - connects
sup middle cerebral vein to SSS
 Vein of Labbe’ ( inferior anastomotic
vein ) - connects sup middle cerebral vein to
Transverse sinus

9. Functions
 PRIMARY SOMASTHETIC AREA - Body image representation
(AREA 3,1,2 ) - tactile perception
-somato sensory perception
 SOMASTHETIC ASSOCIATION AREA -Body in space
(AREA 5,7) -Tactile discrimination
 SUPERIOR PARIETAL LOBULE AND AREA 7
-3 D analysis of body space interactions (body schema)
- Visual spatial properties
- Visual attention
-Motivation and grasping functions
 INFERIOR PARIETAL LOBULE- Last to mature anatomically and
functionally. So, the functions are late, to develop b/w 5 and 8 yrs age.
( reading , calculations )

10. Either Hemisphere
 1. Cortical sensations.
 2. Integration of sensory , motor and attention signals (i.e
disengage attention - do other activity -immediately
reengage correctly)
 3. Optic radiation passes through
 4. Constructional ability – capacity to construct or draw
3D/2D figures or shapes
 5. Short term memory
Lt. – immediate recall for digits and words
Rt. – immediate recall for geometric patterns

11. Left hemisphere
 1. Language – comprehension
reading
writing
 2. Calculations – verbal rote calculations and
recognition of signs.
 3. Non verbal symbolization (pantomime)

12. right hemisphere
 1. Constructional skills
 2. spatial orientation
 3. Perceptual functions (inattention/neglect of lt. hemispace)

13. CLINICAL EFFECTS OF PARIETAL LOBE LESIONS
Either hemi sphere
 • CORTICAL SENSORY SYNDROMES
 • TOPOGRAPHICAL DISORIENTATION
 • VISUOSPATIAL DIFFICULTIES
 HEMINEGLECT
 • Total hemi anesthesia with large acute lesion of Parietal
lobe.white matter
 Mild hemi paresis, unilateral muscular atrophy in children,
hypotonia, poverty of movements, hemiataxia
 Homonymous hemianopia [incongruent or congruent],
 Neglect of the opposite isde of external space

14. CORTICAL SENSORY SYNDROMES
Cortical defect is essentially one of sensory discrimination
i.e impaired ability to integrate and localize stimuli.
 1. Loss of position sense and passive movement.
 2. Topagnosia – loss of localization of tactile, thermal and
noxious stimuli.
 3. Astereognosis-loss of ability to recognize object by
touch.
 4. Agraphesthesia.
 5. Loss of ‘two point’ discrimination

15. HEMI NEGLECT
 neglect on one side of body in dressing and grooming
 Shave only one side or use only one sleeve of shirt
 Deviation of head and eyes to side of lesion
.
 Torsion of body to the side of lesion.
 Fail to use one side of body, even though paralysis is not present
 Finds impossible to wear eye glasses.
 Sensory extinction - is subtle form of neglect

16. DOMINANT PARIETAL LOBE
 1. Disorders of language ( anomia, aphasia, alexia, agraphia
 2. Gerstmann syndrome
 3. Tactile agnosia (bimanual astereognosis)
 4. Bilateral ideomotor and ideational apraxia.
 5.VARIOUS FORMS OF DYSPHASIA

17. GERSTMANN SYNDROME
. • An example of bilateral
asomatognosia and is due to a
left dominant parietal lesion
 .1. Finger agnosia
 2. Right-left confusion
 3. Acalculia
 4. Dysgraphia

18. NON DOMINANAT PARIETAL LOBE
 Disturbed appreciation of the body image and of external
space,particularly involving C/L side
 The left limbs may fail to be recognised or may be dishonoured by the
patient
 If the patient is paralysed or hemianaesthetic, the disability may be
ignored/refuted (anosognosia)
 Hemisomatognosia(a part of the body may be felt to be absent
 Neglect of the left half of the external space
 Dressing dyspraxia
 Visuospatial agnosia

19. NON DOMINANAT PARIETAL LOBE
 1. Topographic disorientation
 2. Topographic memory loss
 3. Anosognosia /dressing apraxia
 4. Constructional apraxia
 5. Hemi-inattention
 6. Apraxia of eye opening
 7. Confusion

21. BOUNDARIES
 The occipital lobe is located
in the posterior (back)
region of the
cerebrum, superior
to (above) the cerebellum.
 Separated from parietal lobe
by:
Parieto-occipital sulcus

22. Brodmann Cortical Areas
 Area 17
either side of calcarine
fissure
primary visual area
 Area 18, 19
Inferior portion of
occipital lobe on lateral
brain surface
secondary visual
(association)
where visual proccessing
occurs

23. sulci
 parieto occipital sulcus
 Calcarine sulcus
 Lunate sulcus
 Transeverse sulcus

24. gyri
 Cuneate gyrus
 Lingual gyrus
 Fusi form gyrus

27. Functions
 Occipital lobe is visual processing centre of brain.

28. Effects of diseases of occipital lobe
1)Effects of unilateral either righr or left
 Contra lateral homonymous hemianopia,homonymous
hemiachromatopsia
 Elimentary(unformed)hallucinations
2)Effects of left occipital disease
 right homonymous hemianopia
 Alexia and colour naming defect
 Visual object agnosia

29. 3)effect of right occipital disease
 Left homonymous hemi anopia
 Visual illusions,hallucinations
 Loss of topographic memory and visual orientation
4)Bilateral occipital disease
 Cortical blindness
 Anton syndrome (visual anosognosia,denial of cortical
blindness)
 Loss of perception of color
 Prosopagnosia
 Balint syndrome

30. BALINT SYNDROME
 Triad of severe neurophysiological impairments
-inability to perceive the visual field as a whole
-difficulty in fixating eyes(occulomotor apraxia)
-inability to move the hand to a specific object by
using vision

31.  Thank you