Gyri and Sulci of the Brain

Brain Sulci and Gyri
The brain is divided into two cerebral hemispheres and is responsible for conscious thought, emotion and voluntary movement. The folds on its surface are known as gyri and the grooves are known as sulci. PASIEKA/Science Photo Library/Getty Images

The brain has a unique appearance that consists of many folds or ridges and indentations. A brain ridge is known as a gyrus, while an indentation or depression is a sulcus or fissure. The cerebral cortex consists of gyri that are typically surrounded by one or more sulci. Gyri and sulci give the brain its wrinkled appearance. The cerebral cortex is the most highly developed area of the brain and is responsible for higher brain functions such as thinking, planning and decision making.

Key Takeaways: Brain Gyri and Sulci

  • Gyri and sulci folds and indentations in the brain that are responsible for its wrinkled appearance.
  • Gyri (gyrus singular) are the folds or bumps in the brain and sulci (sulcus singular) are the indentations or grooves in the brain.
  • Folding of the cerebral cortex creates gyri and sulci which separate brain regions, increase the brain's surface area, and increase cognitive ability.
  • Gyri and sulci form boundaries between the lobes of the brain and divide the brain into two hemispheres.
  • An example of a sulcus is the interhemispheric or medial longitudinal fissure that separates the left and right brain hemispheres. The corpus callosum is found within this fissure.
  • An example of a gyrus is Broca's gyrus, an area of the brain that is noted in speech production.

Gyri and Sulci Function

Brain gyri and sulci serve two very important functions. These hills and valleys help to increase the surface area of the cerebral cortex. This allows more neurons to be packed into the cortex and increases the brain's ability to process information. Gyri and sulci also form brain divisions by creating boundaries between the lobes of the brain and dividing the brain into two hemispheres.

The cerebral cortex is divided into four lobes. The frontal lobes are located in the front-most region of the cerebral cortex. The parietal lobes and temporal lobes are positioned behind the frontal lobes, with the parietal lobes positioned above the temporal lobes. The occipital lobes sit at the posterior region of the cerebral cortex. Each of these brain lobes are responsible for several important functions. The frontal lobes are vital for motor control, thinking, and reasoning. The parietal lobes process sensory information, while the occipital lobes are the main centers for visual processing. The temporal lobes are important for language and speech production, as well as for memory and emotion processing.

Brain Sulci or Fissures

Below is a listing of several key sulci in the brain.

  • Interhemispheric (Medial Longitudinal Fissure): This is a deep furrow located down the center of the brain that separates the left and right brain hemispheres. The corpus callosum is located within this fissure.
  • Fissure of Sylvius (Lateral Sulcus): This deep grove separates the parietal and temporal lobes.
  • Central Sulcus (Fissure of Rolando): This sulcus separates the parietal and frontal lobes.
  • Collateral Sulcus: This furrow separates the fusiform gyrus and the hippocampal gyrus on the lower surface of the temporal lobes.
  • Parieto-occipital Sulcus: This deep crevice separates the parietal and occipital lobes.
  • Calcarine Sulcus: This grove is located in the occipital lobes and divides the visual cortex.

Brain Gyri

Listed below are a number of important gyri of the cerebrum.

  • Agular Gyrus: This fold in the parietal lobe is the area of the brain that assists in processing auditory and visual stimuli. It is also involved in language comprehension.
  • Broca's Gyrus (Borca's Area): This area of the brain, located in the left frontal lobe in most individuals, controls motor functions involved with speech production.
  • Cingulate Gyrus: This arch-shaped fold in the brain is located above the corpus callosum. It is a component of the limbic system and processes sensory input concerning emotions and regulates aggressive behavior.
  • Fusiform Gyrus: This bulge located in the temporal and occipital lobes consists of lateral and medial parts. It is thought to play a role in facial and word recognition.
  • Hippocampal Gyrus (Parahippocampal Gyrus): This fold on the inner surface of the temporal lobe borders the hippocampus. The hippocampal gyrus surrounds the hippocampus and plays an important role in memory.
  • Lingual Gyrus: This convolution of the occipital lobe is involved in visual processing. The lingual gyrus is bordered by the calcarine sulcus and collateral sulcus. Anteriorly, the lingual gyrus is continuous with the parahippocampal gyrus and together they form the medial portion of the fusiform gyrus.

    Gyri and sulci are very important features of the central nervous system. Folding of the cerebral cortex creates these ridges and grooves which serve to separate brain regions and increase cognitive ability.