The parietal lobe receives vascular supply from several arteries. It is involved in somatosensory processing and functions like reading, writing, and computing. Lesions can cause deficits such as hemispatial neglect, Gerstmann's syndrome, and Balint's syndrome. The optic nerve pathway transmits visual information from the retina to the visual cortex in the occipital lobe via the lateral geniculate nucleus in the thalamus. Lesions in different parts of this pathway cause specific visual field defects.

1. Parietal
lobe
Akanksha krishan Sharma

2. Vascular supply
 Lateral
 MCA
 Medial
 ACA
 PCA (To a slight extent)

3. Anatomy

4. Boundries
• ANTERIORLY : CENTRAL SULCUS
• POSTERIORLY : UPPER PART OF I
IMAGINARY LINE
• INFERIORLY : POST RAMUS OF
LATERAL SULCUS AND II
IMAGINARY LINE

5. Sulci
• POSTERIOR CENTRAL SULCUS
• INTRAPARIETAL SULCUS

6. Intraparietal sulcus divides it into
sup and inferior lobule
• SUPRAMARGINAL GYRUS
SURROUNDING THE POST. RAMI
OF THE LATERAL SULCUS
• ANGULAR GYRUS
SURROUNDS THE SUPERIOR
TEMPORAL SULCUS
• TEMPORAL OCCIPITALIS
SURROUNDS THE INFERIOR
TEMPORAL SULCUS

7. Primary
somatosensory
3,1,2
Locationt: postCentral gyrus
Function: exteroceptive (pain, touch,
temperature) sensation.
proprioceptive
( Vibration, muscle
And joints)sensation
Lesion: loss of appreciation of
exteroceptive and proprioceptive
sensation from opp. Half of body
Sensory association
5,7
Location: sup parietal lobule
Function : steriognosis ( perception
of shape,size roughness, texture of
objects
Lesion: asterognosis/ tactile agnosia
( inability to identify object by its
feel)
Inferior parietal
lobule
Location: angular gyrus,
supramarginal gyrus
Function: learning= reading, writing,
computing
Lesion: aphasic disorders
. Alexia
Agraphia
Acalculia
Anomia
Areas

8. Primary somatosensory Area

9. Sensory association area

10. Inferior parietal lobule

11. Lesions of parietal lobe

12. Hemispatial neglect
Traditional view: caused by parietal lobe lesion.
Parietal frontal network for spatial orientation
Cortical components Subcortical components
Cingulate cortex
( Limbic mapping of extra personal space)
Straitum
Posterior parietal complex (sensorimotor
representation of extra personal space events)
Thalamus
Frontal eye fields
( To motor strategies for attention behaviour)

13. U/l left hemisphere lesion : no contralateral neglect
U/l right hemisphere lesion: severe left hemispatial neglect

14. Symptoms
BEDSIDE TEST
SIMULTANEOUS B/L STIMULATION TEST
VISUAL TARGET CANCELLATION

15. Balint’s syndrome
SEVERE SPATIAL
DISORIENTATION
B/L DORSAL PARIETAL LESION
MC: WATERSHED INFARCT B/W MCA
AND PCA
: SAGITTAL SINUS THROMBOSIS
: ALZHEIMER’S DISEASE

16. Deficits
Oculomotor
apraxia
Orderly
visuomotor
scanning
Optic ataxia Accurate manual
reaching towards
visual target
Simultanagnosia Inability to
integrate visual
info with centre
gaze
Dressing apraxia Unable to align
body’s axis with
axis of garment
Construction
apraxia
Difficulty in
copying simple
line drawing

17. Letter target test

18. Gerstmann’s
syndrome
Acalculia
Dysgraphia
Finger anomia
Right left confusion
Lesion site : angular gyrus in
inferior parietal lobule in left
hemisphere

19. Transcortical sensory
aphasia
comprehension for Spoken and
written impaired
Repition intact
Lesion sperate language area from
temporoparietal assoc area
ISOLATION APHASIA
COMPREHENSION IMPAIRED NO
PURPOSEFUL SPEECH OUTPUT
PARROT FRAGMENTS
PATCHY LESION ASSOC WITH CARBON
MONOXIDE POISONING, COMPLETE
WATERSHED ZONE INFARCTION

21. Optic
nerve
pathway

22. Unique features:
Peripheral nerve or tract ??
Development – stalk of optic vesicle.

23. OPTIC
NERVE
PATHWAY

24. OPTIC NERVE
COMPRISE OF AXONS OF
GANGLION CELLS
EXTENDS FROM OPTIC DISC
TO CHIASMA
PARTS
Intraocular 1mm
Intraorbital 30mm
Intra canalicular 6-7mm
Intra cranial 10 mm

25. VON WILLEBRAND KNEE

26. SECOND ORDER CELLS
RELAYS HERE.
IT IS A THALAMIC NUCLEI
PRESENT IN MIDBRAIN.
EXACT POINT TO POINT
TRANSMISSION OF
INFORMATION FROM
RETINA TO VISUAL
CORTEX.
CONSISTS OF 6 LAYERS
OF NEURONS (GREY
MATTER) ALTERNATING
WITH WHITE MATTER.
LGB

27. VISUAL CORTEX
• AREA 17 VISUOSENSORY
• AREA 18 PERISTRIATE
• AREA 19 PARASTRIATE
AREA 18, 19 VISUOPSYCHIC

29. Temporal rotation of fibres

30. PROJECTION OF
RETINA ON LGB AND
VISUAL CORTEX

31. OPTIC NERVE LESIONS
1. Optic nerve Total blindness on affected
side
2. Centre of optic chiasma Bitemporal hemianopia
3. Proximal part of optic
chiasma
R: temporal hemianopia
L: sup.Nasal quadrantopia
3b. Lateral part of optic
chiasma
U/l nasal hemianopia
4. Optic tract Homonemus hemianopia
4a. Ventral 2/3 LGB B/l sup. Quadrantopia
4. Dorsal 1/3 LGB B/l inf quadrantopia
5. Optic radiation Homonemus hemianopia
6. Visual cortex Homonemus hemianopia
with sparing of macula
6. Upper tip of calcarine
sulcus
Contralateral inferior
quadrantopia
7. Lower tip of calcarine
sulcus
Contralateral superior
quadrantic anopia

32. BLOOD SUPPLY