Posterior parietal lobe lesions may cause a neglect syndrome or sensory inattention, with impaired attention to stimuli in the contralateral half of the visual field. These contribute to reading, writing and arithmetic in the language-dominant hemisphere.
The inferior parietal lobule consists of the angular and supramarginal gyri. The superior parietal lobule has close links with the occipital lobe and is involved in aspects of attention and visuospatial perception, including the representation and manipulation of objects. The postcentral gyrus corresponds to the primary somatosensory cortex and contains an inverted map of the contralateral body, mirroring that of the motor strip. Its posterior boundary (with the occipital lobe) is the parieto-occipital sulcus. The parietal lobe is posterior to the central sulcus and above the lateral sulcus. It is also involved in spatial and symbolic representation of abstract concepts including quantity and number. The inferior parietal lobule contributes to aspects of receptive language such as phonology, reading and spelling, particularly in the language-dominant hemisphere. It consists of the supramarginal gyrus ( BA 40) anteriorly and the angular gyrus ( BA 39) posteriorly. The inferior parietal lobule is a multimodal association area which lies at the junction of the visual, auditory and somatosensory cortices. Certain semi-automatic movements are initiated by projections from the parietal cortex to the lateral premotor area ( Clinical Box 3.3). judging the approach of a moving vehicle). using a knife and fork) and the perception of movement (e.g. This includes the representation and manipulation of objects (e.g. The posterior parietal cortex ( BA 7) has close links with the occipital lobe and is concerned with visuospatial perception and attention ( Clinical Box 3.2). Lesions here may lead to astereognosia: the inability to recognize objects by touch (Greek: a-, without stereos, solid gnosis, knowledge). The somatosensory association cortex ( BA 5) is a small area in the superior parietal lobule, just behind the sensory strip. This is a deep cleft at right angles to the central sulcus. The remainder of the lateral parietal lobe is divided into superior and inferior parietal lobules by the intraparietal sulcus.
The sensory strip contains an inverted map of the opposite side of the body that mirrors that of the motor strip, but the relative proportions of the body parts reflect the degree of tactile sensitivity. It corresponds to the primary somatosensory cortex ( BA 3, 1 and 2). The postcentral gyrus is immediately posterior to the central sulcus, behind and parallel to the motor strip. The parietal lobe is concerned with somatosensory and visuospatial perception. Its posterior boundary is the parieto-occipital sulcus, which is only visible from the medial aspect of the cerebral hemisphere. Paul Johns BSc BM MSc FRCPath, in Clinical Neuroscience, 2014 Parietal lobe
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