Superolateral surface of cerebrum (Sulci and Gyri)

INTRODUCTION

Cerebral cortex is folded into gyri which are separated from each other by sulci. This pattern increases the surface area of the cortex. In human brain, the total area of the cortex is estimated to be more than 2000 cm², and approximately 2/3 of this area is hidden from the surface within the sulci.

Superolateral surface of cerebrum consist of all the four lobes of the cerebral hemispheres – frontal lobe, parietal lobe, temporal lobe, and occipital lobe, each of which are anatomically identified using specific gyri and sulci.

These lobes of cerebral hemispheres are divided into different parts by central sulcus, lateral sulcus and parieto-occipital sulcus.

SULCI AND GYRI OF FRONTAL LOBE

1. Precentral sulcus – It runs parallel to central sulcus anteriorly.
2. Precentral gyrus – It lies between the central and precentral sulcus.
3. Superior frontal sulcus – It extends superiorly and anteriorly from the precentral sulcus.
4. Superior frontal gyrus – It lies superior to the superior frontal sulcus.
5. Inferior frontal sulcus – It extends inferiorly and anteriorly from the precentral sulcus.
6. Middle frontal gyrus – It lies between the superior and inferior frontal sulci.
7. Inferior frontal gyrus – It lies inferior to the inferior frontal sulcus.

Note : The anterior horizontal and anterior ascending rami of the lateral sulcus subdivide the inferior frontal gyrus into three parts – pars orbitalis, pars triangularis, and pars opercularis.

SULCI AND GYRI OF PARIETAL LOBE

1. Postcentral sulcus – It runs parallel to central sulcus posteriorly.
2. Postcentral gyrus – It lies between the postcentral sulcus and central sulcus.
3. Intraparietal sulcus – It runs posteriorly from the middle of the postcentral sulcus.
4. Superior parietal lobule (gyrus) – It lies superior to intraparietal sulcus.
5. Inferior parietal lobule (gyrus) – It lies inferior to intraparietal sulcus. It is divided into 3 parts – the anterior, the middle and the posterior.

SULCI AND GYRI OF TEMPORAL LOBE

1. Superior temporal sulcus
2. Inferior temporal sulcus
3. Superior temopral gyrus
4. Middle temporal gyrus
5. Inferior temporal gyrus

The superior and middle temporal sulci run parallel to the posterior ramus of the lateral sulcus and divide the temporal lobe into the superior, middle, and inferior temporal gyri.

SULCI AND GYRI OF OCCIPITAL LOBE

1. Lateral occipital sulcus – It divides the lobe into the superior and inferior occipital gyri.
2. Lunate sulcus – It separates superior and inferior occipital gyri from the occipital pole.
3. Parieto-occipital sulcus – The area around the it is marked by arcus parieto-occipitalis. It is separated from the superior occipital gyrus by the transverse occipital sulcus.
4. Calcarine sulcus – It begins near the occipital pole in two converging rami and runs forward to a point below the splenium of corpus callosum.

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