What Is It, Location, Function, and More
Author:Katie Arps, BSN, RN
Editors:Anna Hernández, MD,Ian Mannarino, MD,Kelsey LaFayette, DNP, ARNP, FNP-C
Illustrator:Jessica Reynolds, MS
Copyeditor:David G. Walker
What is the parietal lobe?
The parietal lobe is a region of the brain responsible for processing somatosensory information, including touch, pain, temperature, and joint position. It is also involved in integrating sensory information among various modalities into a deeper meaning, which allows individuals to locate exactly where they are physically and guides movements in a three-dimensional space (i.e., proprioception).
Where is the parietal lobe located?
The parietal lobes are located in the cerebrum, or the large, uppermost portion of the brain. The cerebrum consists of two nearly symmetrical halves called the right and left hemispheres, which are separated by the medial longitudinal fissure. Each cerebral hemisphere is divided into four main lobes, including the frontal, parietal, temporal, and occipital lobes. The parietal lobe is located posterior to the frontal lobe, anterior to the occipital lobe, and superior to the temporal lobe. The boundary separating the parietal lobe from the frontal lobe is the central sulcus, while the parieto-occipital sulcus separates the parietal lobe and the occipital lobe. Finally, the lateral sulcus, otherwise known as the Sylvian fissure, separates the parietal and temporal lobes. The parietal lobe can be further divided into three areas: the postcentral gyrus, the superior parietal lobule, and the inferior parietal lobule. The postcentral gyrus lies directly posterior to the central sulcus, and the inferior and superior parietal lobules are in the posterior portion of the parietal lobe separated by the intraparietal sulcus.
What are the functions of the parietal lobe?
The functions of the parietal lobe are to receive and interpret somatosensory signals (e.g. tactile and position sensations) as well as integrate sensory inputs from different parts of the body in order to create a deeper understanding of one's surroundings and body position. The somatic senses, including touch, vibration, pressure, pain, temperature, and joint position are processed in the primary somatosensory cortex (S1) located in the postcentral gyrus of the parietal lobe. This information is then passed to the somatosensory association area located in the posterior portions of the parietal lobe. Here, important higher level processing occurs as information signals from the somatosensory cortex, areas of the thalamus, the primary visual cortex (V1) of the occipital lobe, and the primary auditory cortex (A1) of the temporal lobe are integrated together. This creates an overall picture of spatial orientation and one’s body position in relation to the environment. This information is then relayed to the motor cortex portions of the brain located in the frontal lobe so that muscle contractions can occur accordingly to coordinate the body’s movements.
What happens if the parietal lobe is damaged?
Damage to the parietal lobe may result in various symptoms related to the somatic senses, depending on the injury location. Damage to the primary somatosensory cortex may cause the inability to localize sensation, which means an individual may be able to describe where the sensation is located generally, such as a particular limb or side of the body, but cannot identify the exact location. This deficit includes the inability to separately identify two cutaneous stimuli placed closely together, which is known as two-point discrimination, as well as the inability to identify numbers or letters traced on the skin with a finger, which is known as graphesthesia. One may also lose the ability to determine changes in pressure against their body or be unable to determine the weight, texture, and form of objects.
Damage to the somatosensory association area of a parietal lobe can result in the inability to recognize complex objects or even the sense of one’s own body on the side that is opposite to the parietal injury. For example, an injury to the right parietal lobe may cause the inability to identify objects felt on their left side or the individual may become unaware that the left side of their body exists, a phenomenon known as hemispatial neglect. An example of hemispatial neglect is construction apraxia where, when asked to draw a clock, the individual draws all the numbers on half of the clock but is unaware they have not drawn the other side; or dressing apraxia, where they only dress half of their body. The individual may also experience anosognosia, which is an indifference or lack of ability to recognize their condition.
Since the parietal lobe is responsible for spatial relations and the visual mapping of one’s surroundings, symptoms in which body movements rely on this information may be present. For example, optic ataxia occurs when a person reaches out to grasp an object but incorrectly positions their arm and hand to successfully do so, missing the target.
Finally, parietal lobe damage inhibits the ability to integrate visual, acoustic, and somatosensory information in order to understand and solve problems, particularly with regards to speech and number processing. As a result, this may lead to acalculia, which is the inability to perform mathematical calculations, and agraphia, which is the inability to write. Furthermore, some lesions may result in alexia (the inability to read) and oraphasia (the inability to formulate or comprehend language).
The parietal lobe can be damaged as a result of a traumatic brain injury, including those resulting from accidents, falls, and firearm injuries. Certain neurological disorders may affect the function of the parietal lobe, including vascular conditions (e.g. stroke, cerebral hemorrhage, and cerebral artery aneurysms); infections (e.g. meningitis and encephalitis); tumors; and autoimmune diseases, such as lupus and multiple sclerosis. The parietal lobe can also be damaged as a result of severe and repetitive seizures, which can subsequently increase vulnerability for future seizures.
What are the most important facts to know about the parietal lobe?
The parietal lobe plays a crucial role in processing and integrating sensory information. The anterior portion of the parietal lobe, called the primary somatosensory cortex, processes the somatic senses to interpret tactile and position sensations. The somatosensory association area then integrates this information, along with sensory information from the visual and auditory cortexes and the thalamus to provide a deeper understanding of the body’s positions, movements, and surroundings. The parietal lobe can be injured by trauma, tumor, vascular injury, seizures, and certain autoimmune diseases. This may result in hemispatial neglect; optic ataxia; and the inability to localize sensation, recognize two-point discrimination, or determine certain aspects of an object (such as the weight, texture, and form) as well as other conditions.
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Resources for research and reference
Hall, J. E. (2016). Guyton and Hall textbook of medical physiology (13th ed.). Elsevier.
Irshad, M. (2018, September 7). The cerebrum. In TeachMeAnatomy. Retrieved May 16, 2022, from https://teachmeanatomy.info/neuroanatomy/structures/cerebrum/
Jameson, J. L. (Ed.). (2018). Harrison’s principles of internal medicine (20th ed.). McGraw-Hill Education.
Purves, D., & Williams, S. M. (Eds.). (2001). Neuroscience (2nd ed.). Sinauer Associates.Shahid, S. (2022, May 4). Parietal lobe. In Kenhub. Retrieved May 16, 2022, from https://www.kenhub.com/en/library/anatomy/parietal-lobe