Gyri and Sulci

This page is effectively an Appendix to the A Grey Anatomy: Mapping the Cortex blog post.

Image: Gray’s division of the hemisphere into 4 lobes (source: Wikipedia).

It goes around the various lobes in turn, pointing out the names of the gyri (ridges) and sulci (furrows) of the human brain.

Image: Gray’s lateral view of the hemisphere (source: Wikipedia), showing gyri and sulci of all 4 lobes.

The Frontal Lobe

The frontal lobe is divided into:

  • Prefrontal’ part (forehead)
  • Precentral’: (between the ‘Prefrontal’ and the Central sulcus separating the Frontal and Parietal lobes)

In the ‘Prefrontal’ area, going superolaterally (on the outside surface of brain) from the centre of the forehead, laterally down towards the temporal lobe, there is in turn:

  • Superior frontal gyrus, includes the paracentral lobule towards the top of the head, after the paracentral sulcus.
  • Superior frontal sulcus.
  • Middle frontal gyrus.
  • Inferior frontal sulcus.
  • Inferior frontal gyrus: includes the Pars opercularis (“the part that covers” the insula) and the Pars triangularis.

Image: Gray’s superior view of the hemisphere (source: Wikipedia), showing gyri and sulci, mainly of the frontal lobe.

On the concave underside of the frontal lobe, from above the nose, laterally, over the eye:

  • straight gyrus.
  • olfactory sulcus.
  • medial orbital gyrus.
  • anterior orbital gyrus.
  • lateral orbital gyrus.
  • posterior orbital gyrus.
  • orbital sulci (‘H’ shaped between the above 4).

Medially/inferior (middle/lower surfaces):

  • paraterminal gyrus.

Image: Gray’s inferior view of the frontal lobe showing gyri and sulci (source: Wikipedia).

Physical location: The Parietal lobe

Superolaterally, front to back:

  • Postcentral gyrus just behind the central fissure.
  • Upper superior parietal lobule and more lateral Inferior parietal lobule (with the supramarginal gyrus in front of the angular gyrus), separated by the Intraparietal sulcus.

Laterally, tucked behind the temporal lobe:

  • Parietal operculum

On the Medial surface (where the hemispheres meet) from front to back:

  • Marginal sulcus separates the precuneus from the paracentral.
  • Precuneus: superior (upper)

Physical location: The Temporal lobe

Superolaterally (outside surface), from top of the temporal lobe down towards the ear:

  • Superior temporal gyrus.
  • Superior temporal sulcus.
  • Middle temporal gyrus.
  • Inferior temporal sulcus.
  • Inferior temporal gyrus.

Image: Gray’s superior view of the temporal lobe showing the transverse gyri and sulci (source: Wikipedia).

On top of the temporal lobe, running transversely:

  • Transverse temporal gyrus.

Inferior and medially:

  • Inferior temporal gyrus.
  • Inferior temporal sulcus.
  • Fusiform gyrus (“spindle”: wide in the middle; narrow at the ends).
  • Collateral sulcus.
  • Parahippocampal gyrus (around the hippocampus).
  • Hippocampus (“seahorse”, about the same size as one)
  • Rhinal sulcus.
  • Dentate gyrus.
  • Subiculum (“support”).

Image: Gray’s lateral cut-away view of the hemisphere (source: Wikipedia) showing the deep lateral fissure between the parietal and temporal lobes and also the hippocampus.

Physical location: The Occipital lobe

Superolaterally (top down to side):

  • Superior occipital gyrus.
  • Lateral occipital gyrus.
  • Inferior occipital gyrus.

In front of this, from the top of the lobe then medially:

  • Transverse occipital sulcus.

And behind:

  • Occipital pole of cerebrum: the rear-most part of the brain.

Image: Gray’s transverse cross-section of the occipital lobe (source: Wikipedia) showing sulci and gyri.

Medially, from top to bottom:

  • Cuneus (‘wedge’).
  • Calcarine fissure.
  • Lingual gyrus.

Image: Gray’s lower horizontal cross-section of the hemisphere (source: Wikipedia) showing just the genu of the corpus callosum plus the atypical grey/white matter structure towards the occipital lobe.

Physical location: The Insula Lobule

Folded deep within the lateral sulcus between the temporal and frontal lobes is the Insula, with:

  • A deep circular sulcus separating the insula from the frontal, parietal, and temporal lobes.
  • Towards the front are 3 or 4 short gyri of insula.
  • Posterior is the long gyrus of insula.

Image: Gray’s lateral view of the insula (source: Wikipedia) showing the circular sulci and short and long gyri.

Physical location: The Limbic Lobe

The medial view of the hemisphere shows the cingulate sulcus above the corpus callosum, which divides the limbic lobe (in as far is it may be considered a lobe, at all) from the combined frontal and parietal lobes. Between the cingulate sulcus and the corpus callosum are the cingulate gyrus (cingulus=”belt”) and supracallosal gyrus.

Image: Gray’s medial view of the hemisphere, showing gyri and sulci at the sagittal plane (source: Wikipedia) showing the Cingulate gyrus and also the shape of the corpus callosum.

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One Response to Gyri and Sulci

  1. Pingback: A Grey Anatomy: Mapping the Cortex | Headbirths

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