The parietal lobe (lobe – from the Greek lobos, parietal – from the Latin paries, -etis, meaning wall) constitutes one of the regions of the brain, located behind the frontal lobe and above the temporal and occipital lobes.

Position. The parietal lobe is located at the level of the parietal bone. It is positioned above the temporal and occipital lobes, and behind the frontal lobe. It is separated from the other lobes by different grooves:

• The central sulcus, or Rolando sulcus, separates it from the frontal lobe.
• The lateral sulcus, or Sylvius sulcus, separates it from the frontal and temporal lobe.
• The parito-occipital furrow separates it from the occipital lobe at the back.

Main structure. The parietal lobe is one of the regions of the brain. The latter is the most developed part of the brain and occupies most of it. It is made up of neurons, the cell bodies of which are located on the periphery and form the gray matter. This outer surface is called the cortex. The extensions of these bodies, called nerve fibers, are located in the center and form the white matter. This internal surface is called the medullary region (1) (2). Numerous furrows, or cracks when they are deeper, distinguish different areas within the brain. The longitudinal fissure of the brain allows it to be separated into two hemispheres, left and right. These hemispheres are connected to each other by commissures, the main of which is the corpus callosum. Each hemisphere is then divided, through the primary sulcus, into four lobes: the frontal lobe, the parietal lobe, the temporal lobe and the occipital lobe (2) (3).

Secondary and tertiary structures. The parietal lobe has secondary and tertiary grooves, making it possible to form convolutions called gyri. The main parietal lobe gyri are:

• le gyrus postcentral,
• the superior parietal lobule,
• the lower parietal lobule,
• le gyrus supramarginal,
• the angular gyrus.

The cerebral cortex is associated with mental, sensitivomotor activities, as well as the origin and control of skeletal muscle contraction. These different functions are distributed in the different lobes of the brain (1).

Parietal lobe function. The parietal lobe essentially has somatosensory functions. One distinguishes in particular the primary sensory field located at the level of the postcentral gyrus, corresponding to the bodily sensitivity. It also has Wernicke’s area, associated with speech, as well as the reading center (2) (3).

Of degenerative, vascular or tumor origin, certain pathologies can develop in the parietal lobe and affect the central nervous system.

Stroke. Cerebrovascular accident, or stroke, occurs when a cerebral blood vessel is blocked, such as the formation of blood clots or the rupture of a vessel4. This pathology can impact the functions of the parietal lobe.

Head trauma. It corresponds to a shock to the skull which can cause brain damage, in particular to the parietal lobe. (5)

Multiple sclerosis. This pathology is an autoimmune disease of the central nervous system. The immune system attacks the myelin, the sheath surrounding nerve fibers, causing inflammatory reactions. (6)

Brain tumor. Benign or malignant tumors can develop in the brain, especially in the parietal lobe. (7)

Degenerative cerebral pathologies. Certain pathologies can lead to changes in nervous tissue in the brain.

Alzheimer’s disease. It results in a modification of cognitive faculties with in particular a loss of memory or reasoning. (8)

Parkinson disease. It is manifested in particular by a tremor at rest, a slowing down and a reduction in the range of motion. (9)

Drug treatments. Depending on the pathology diagnosed, certain treatments may be prescribed such as anti-inflammatory drugs.

Thrombolyse. Used during strokes, this treatment consists of breaking up the thrombi, or blood clots, with the help of drugs. (4)

Surgical treatment. Depending on the type of pathology diagnosed, surgery may be performed.

Chemotherapy, radiotherapy, targeted therapy. Depending on the stage of the tumor, these treatments can be implemented.

Physical examination. First, a clinical examination is performed in order to observe and assess the symptoms perceived by the patient.

Medical imaging exam. In order to assess brainstem damage, a cerebral and spinal CT scan or a cerebral MRI can in particular be performed.

biopsy. This examination consists of a sample of cells.

Lumbar puncture. This exam allows the cerebrospinal fluid to be analyzed.

Wernicke area. Highlighted by the German neurologist Carl Wernicke in the 1870s, Wernicke’s area is the area associated with speech processing.