Presenter :Dr S. Vidya sagar

Moderator : Dr V. Sharbandhraj

Over view

Anatomic& physiological considerations

Boundaries

Sulci &Gyri

Brodmanns area

Blood supply

Functions

Rightlobe functions

left lobe functions

Dysfunctions & SyndromesEither parietal lobe lesions

Dominant &non dominant lesions

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 anteroposteriorly from the post central sulcus

Inter parietal sulcus separates the mass of parietal lobe in to superior & inferior lobules

gyri

Inferior lobule is composed of the supra marginal gyrus and angular gyrus.

Post central gyrus –primary somatosensorycortex-recieves most of its afferent projections from the ventro posterior thalami nucleus.

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

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

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 anastomoticvein ) - connects sup middle cerebral vein to Transverse sinus

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 )

Either Hemisphere 1. Cortical sensations.

2. Integration of sensory , motor and attention signals (i.edisengage 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

Left hemisphere

1. Language – comprehension

reading

writing

2. Calculations – verbal rote calculations and

recognition of signs.

3. Non verbal symbolization (pantomime)

right hemisphere

1. Constructional skills

2. spatial orientation

3. Perceptual functions (inattention/neglect of lt. hemispace)

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

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

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

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

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

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

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

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

Brodmann Cortical Areas

Area 17either side of calcarinefissureprimary visual area

Area 18, 19Inferior portion of occipital lobe on lateral brain surfacesecondary visual (association)where visual proccessingoccurs

sulci

parieto occipital sulcus

Calcarine sulcus

Lunate sulcus

Transeverse sulcus

gyri

Cuneate gyrus

Lingual gyrus

Fusi form gyrus

Functions

Occipital lobe is visual processing centre of brain.

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

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

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

Thank you