Anatomy · MU Sofia

CNS · 163. Telencephalon (Cerebrum, Endbrain) - sulci and gyri.

Explains the sulci and gyri of the cerebral hemisphere, starting with how the cortex folds to increase surface area and divide the hemisphere into frontal, parietal, occipital, temporal and limbic lobes plus the hidden insula. It then walks through the major separating sulci, the superolateral, inferior and medial surfaces in turn, with the sulci and gyri of each lobe, and notes the insula's anterior and posterior parts with their functions. Pictures and the corpus callosum landmarks guide the medial surface.

Inside: 5 sections · 7 labelled pictures · 10 flashcards · 4 min

Topic 149 of 264 in the MU Sofia syllabus for Anatomy (Dental Medicine, Year 2). The free AceMed note covers it in 5 sections, about 558 words (4 min of reading), with 10 flashcards.

In this note

  1. SULCI and GYRI
  2. Major sulci separating the lobes of the cerebral hemisphere:
  3. Sulci & Gyri of the superolateral surface:
  4. Sulci & Gyri of the inferior surface:
  5. Sulci & guri of medial surface:

SULCI and GYRI

The telencephalon (endbrain) gives rise to the cerebral hemisphere wich consists of the superficial cerebral cortex, convoluted to form gyri & sulci.

sulci - dipressions

gyri - elevated force

The sulci & gyri increase the surface area.

The sulci & gyri divide the hemisphere into 5 lobes:

  1. 1. Frontal
  2. 2. parietal
  3. 3. Occipital.
  4. 4. temporal
  5. 5. limbic
  • + hidden insula

Major sulci separating the lobes of the cerebral hemisphere:

  1. 1. Central sulcus: It start at the superomedial border just behind the midpoint between frontal & occipital poles
  • It descends on the lateral surface separating the frontal lobe from the parietal lobe
  1. 2. Lateral sulcus:
  • It has stem and 3 rami
  • It seperates frontal and parietal lobes from the temporal lobe
  1. 3. Parieto-occipital sulcus:
  • It appears small in the supero-lateral surface while it is mainly present on the medial surface.
  • Seperates the parietal and temporal lobes from the occipital lobe.

Sulci & Gyri of the superolateral surface:

1) Frontal lobe: it has:

  • Precentral sulcus: parallel to the central sulcus.
  • Precentral gyrus between central and precentral sulci.
  • From the precentral sulcus: 2 parallel sulci:
  • The superior and the inferior frontal sulci.
  • So 3 gyri are formed: superior, middle, and inferior frontal gyri.
  • Notice the inferior frontal gyrus which is divided by the stem and the rami of lateral sulcus into 3 parts: orbital, triangular, and opercular.

2) Parietal lobe:

  • Postcentral sulcus: parallel to the central sulcus.
  • Postcentral gyrus: between central and postcentral sulci.
  • From the postcentral sulcus: one intraparietal sulcus.
  • Superior and inferior parietal lobules above and below the intraparietal sulcus respectively.
  • Notice the supramarginal gyrus “around the end of lateral sulcus” and the angular gyrus “around the end of superior temporal sulcus”.

3) Temporal lobe:

  • 2 sulci parallel to the lateral sulcus: superior and inferior temporal sulci.
  • So 3 gyri are formed: superior, middle, and inferior temporal gyri.

4) Occipital lobe:

  • It shows the end of the calcarine sulcus, with the surrounding lunate sulcus.

N.B: The insula:

  • Present in the floor of the lateral sulcus.
  • Surrounded by a circular sulcus except its apex “limen insulae”
  • Divided by central sulcus into large anterior and small posterior parts.
  • Anterior part having 3-4 short gyri.
  • Posterior part having a long gyrus.

Its function:

  • Anterior part: smell, taste, and autonomic areas.
  • Posterior part: 2nd somatosensory area.

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