The parietal lobe accounts for only 19% of the total neocortical volume (marginally larger than the occipital lobe). 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.
- middle cerebral artery (MCA)
- anterior cerebral artery (ACA): medial parietal lobe
- posterior cerebral artery (PCA): posterior medial parietal lobe
The parietal lobe is vital for sensory perception and integration, including the management of taste, hearing, sight, touch, and smell. It is home to the brain's primary somatic sensory cortex (see image 2), a region where the brain interprets input from other areas of the body. Research suggests that, the more sensory input a region of the body provides, the more surface area of the parietal lobe is dedicated to that area. For example, the fingers and hands are a primary site for sensory data, so much of the parietal lobe is dedicated to receiving and processing their input.
Like all other regions of the brain, the parietal lobe is not fully understood. New studies are consistently making findings about how this brain region works, and it is unlikely that we have identified all of its functions.
Image 2: The figure of a human superimposed on pictures of the surface of the brain to represent the sensory regions of the body represented there.
Because of the parietal lobe's role in sensory integration, spatial reasoning, and language skills, damage to the parietal lobe can have a broad range of consequences. The specific prognosis depends in large part on the location of the injury, the severity of the injury, and whether the injury can be treated. Damage to the Parietal lobes can result in:
- Difficulty with drawing objects
- Difficulty in distinguishing left from right
- Spatial disorientation and navigation difficulties
- Problems with reading (Alexia)
- Inability to locate the words for writing (Agraphia)
- Difficulty with doing mathematics (Dyscalculia)
- Lack of awareness of certain body parts and/or surrounding space (Neglect)
- Inability to focus visual attention
- Difficulty with motor planning and complex movements(Apraxia)
- Certain types of problems are associated with damage caused to either the left or right hemispheres of the cerebral cortex. Damage to the left parietal lobe typically results in difficulties in understanding language and writing. Damage to the right parietal lobe results in difficulties with understanding spatial orientation and navigation.
It is a myth that any single brain region controls any function. Rather, each region of the brain works in conjunction with the body. Without the environment, the brain could do little or nothing, and the parietal lobe is no exception.
- QBI Parietal Lobe Available from:https://www.health.qld.gov.au/abios/asp/bparietal (accessed 3.1.2021)
- Radiopedia Parietal Lobe Available from: https://radiopaedia.org/articles/parietal-lobe(accessed 3.1.2021)
- Spinal cord Parietal Lobe Available from:https://www.spinalcord.com/parietal-lobe (accessed 3.1.2021)