Parietal & occipital lobes

this is ppt of occital &parietal lobes

1. Parietal & Occipital lobes Presenter :Dr S. Vidya sagar Moderator : Dr V. Sharbandhraj

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

3. 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

4. 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.

5. 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

6. 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 

7. 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

8. 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 )

9. 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

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

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

12. 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

13.  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

14. 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

15. 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

16. 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

17. 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

18. 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

19. OCCIPITAL LOBE

20. 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

21. 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

22. sulci parieto occipital sulcus Calcarine sulcus Lunate sulcus Transeverse sulcus

23. gyri Cuneate gyrus Lingual gyrus Fusi form gyrus

24. Functions Occipital lobe is visual processing centre of brain.

25. 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

26. 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

27. 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

28. Thank you