The Parietal Lobe is seperated from the frontal lobe via the central sulcus and via the occipital lobe via the parieto-occipital sulcus
Parietal Lobe Functions
- Post-Central Gyrus (SENSORY cortex)
- Supra-marginal and angular gyrus responsible for making up Wernicke’s language area (dominant lesion). This is called the RECEPTIVE AREA where comprehension from visual and auditory input occurr.
- Visual pathways of the optic radiation occurr deep in the parietal lobe importantly.
Parietal Lobe Lesions
- Post-Central Gyrus- loss of 2 point discrimination, loss of sensation of passive movement, proprioception, accurate loss of sensation of light touch. An important one not to forget in either hemisphere is SENSORY INATTENTION. THIS IS OFTEN TESTED FOR IN STROKE EXAMINATION. Present a patient with two stimuli only able to detect one stimuli from the non-diseased area.
- Supra-marginal gyrus and angular gyrus- Wernicke’s dysphasia
- Non-dominant hemisphere lesion- Anosognosia– not aware of contralateral limb, Apraxia e.g dressing apraxia, Constructional Apraxia (not able to copy geometric pattern), Geographical Agnosia (e.g patient can’t find bed on the ward)
- Dominant Hemisphere Lesions- This is called Gerstmann’s syndrome and typically involves the following features: Acalculia, Agraphia, Finger Agnosia (confusion of right and left fingers)
- Inferior Quadrantinopia (due to damage at the optic radiation)
MRI with contrast showing a hyperintense lesion at parietal lobe.
