Parietal lobe

Changed by Appukutty Manickam, 7 Jan 2018

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The parietal lobe is one of the four lobes of the brain (along with the frontal lobe, temporal lobe, and occipital lobe), located between the frontal and occipital lobes and underlying the parietal bone. It occupies about 25% of the cerebral hemispheres volume.

Gross anatomy

The parietal lobe accounts for only 19% of the total neocortical volume, only marginally larger than the occipital lobe³. The lobe extends from the central sulcus anteriorly, which separates it from the frontal lobe, to the parieto-occipital fissure posteriorly, which separates it from the occipital lobe. The lateral sulcus corresponds to its inferolateral boundary, separating it from the temporal lobe. Medially, it is confined by the medial longitudinal fissure which divides both cerebral hemispheres.

Sulci and gyri

lateral surface
- postcentral gyrus (primary sensory area)
- superior parietal lobule
- inferior parietal lobule (Wernicke's area)
  - supramarginal gyrus
  - angular gyrus
medial surface
- paracentral lobule
- precuneus

Relations

anterior: frontal lobe
posterior: occipital lobe
superior: parietal bone
inferior: temporal lobe

Blood supply

middle cerebral artery (MCA)
anterior cerebral artery (ACA): medial parietal lobe
posterior cerebral artery (PCA): posterior medial parietal lobe

Neurological deficits

~~Deficits~~The following neurological deficits occur with unilateral or bilateral lesions of the parietal lobes⁴:

deficits arising from unilateral lesions involving the dominant hemisphere:
- Gerstmann syndrome: right-left disorientation, finger agnosia, agraphia (without alexia), acalculia
- contralateral hemianopia
- sensory loss
- contralateral neglect
- bilateral astereognosis: inability to identify an object by touch alone
~~Deficits~~
deficits arising from unilateral lesions involving the non-dominant hemisphere:
- contralateral sensory loss
- contralateral neglect
- contralateral hemianopia
- topographic memory loss
- anosognosia: impaired self-awareness
- dressing apraxia
~~Irritative~~
irritative lesions involving either lobe can give rise to the following:
- simple partial seizures involving the contralateral limb
- Jacksonian march: sensory seizures spreading up/down the sensory strip (begins on one side; may begin with thumb/fingers and spread to the wrist, forearm, arm, face and leg; Todd's paresis may ensue)

~~-</ul><h4>Neurological deficits</h4><p>Deficits arising from unilateral lesions involving the dominant hemisphere:</p><ul>~~
+</ul><h4>Neurological deficits</h4><p>The following neurological deficits occur with unilateral or bilateral lesions of the parietal lobes<sup>4</sup>:</p><ul>
+<li>deficits arising from unilateral lesions involving the dominant hemisphere:<ul>
~~-<a title="Gerstmann syndrome" href="/articles/gerstmann-syndrome">Gerstmann syndrome</a>: right-left disorientation, finger agnosia, agraphia (without alexia), acalculia</li>~~
+<a href="/articles/gerstmann-syndrome">Gerstmann syndrome</a>: right-left disorientation, finger agnosia, agraphia (without alexia), acalculia</li>
~~-</ul><p>Deficits arising from unilateral lesions involving the non-dominant hemisphere:</p><ul>~~
+</ul>
+</li>
+<li>deficits arising from unilateral lesions involving the non-dominant hemisphere:<ul>
~~-<a title="anosognosia" href="/articles/anosognosia">anosognosia</a>: impaired self-awareness</li>~~
~~-<li>dressing <a title="Apraxia" href="/articles/apraxia">apraxia</a>~~
+<a href="/articles/anosognosia">anosognosia</a>: impaired self-awareness</li>
+<li>dressing <a href="/articles/apraxia">apraxia</a>
+</li>
+</ul>
~~-</ul><p>Irritative lesions involving either lobe can give rise to the following:</p><ul>~~
+<li>irritative lesions involving either lobe can give rise to the following:<ul>
-<a title="Jacksonian march" href="/articles/jacksonian-march">Jacksonian march</a>: sensory seizures spreading up/down the sensory strip (begins on one side; may begin with thumb/fingers and spread to the wrist, forearm, arm, face and leg; Todd's paresis may ensue)</li>
+<a href="/articles/jacksonian-march">Jacksonian march</a>: sensory seizures spreading up/down the sensory strip (begins on one side; may begin with thumb/fingers and spread to the wrist, forearm, arm, face and leg; Todd's paresis may ensue)</li>
+</ul>
+</li>

References changed:

4. Mark S. Greenberg. Handbook of Neurosurgery. pp. 112–114. (2010) <a href="https://books.google.co.uk/books?vid=ISBN9781604063271">ISBN: 9781604063271</a><span class="ref_v4"></span>

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