Gyri and Sulci of Cerebrum

1. LOBES OF CEREBRAL HEMISPHERE
ITS SULCI AND GYRI
Prepared by: Anish Dhakal
MBBS 3rd Year
anishdhakal718@gmail.com

2. CEREBRUM
• Two hemispheres separated
by median longitudinal fissure
• Band of commissural fibres
corpus callosum at the
bottom of the fissure
• Median longitudinal fissure
occupied by falx cerebri
• Separated from Cerebellum:
tentorium cerebelli

3. SULCUS & GYRUS
• cortex is folded into numerous gyri or convolutions
separated by sulci
• Gyrenchephalic
• Total surface area – thus increased to 2200 cm
square
• 1/3 exposed as gyri
• 2/3 hidden in the walls & floor of sulci

4. SULCUS & GYRUS
• Smooth surface till 3rd month of IUL
• Lateral sulcus – appears during 4th month of IUL
• Other sulci appear during 6th month - central sulcus,
parieto- occipital sulcus, calcarine sulcus, cingulate
sulcus
• All important sulci are laid down by the end of 7th
month of IUL

5. 3 POLES & SIX LOBES

6. Medial surface
Tentorial surface
Superolateral surface
Inferior surface
Orbital

7. CEREBRAL LOBES
• Frontal: anterior to central sulcus
& above the posterior ramus ofthe
lateral sulcus
• Parietal: behind the central sulcus
and in front of the upper part of the
first imaginary line.
• Temporal: lies below the posterior
ramus of lateral sulcus and second
imaginary line.
• Occipital: lies behind the
vertical line joining the parieto-
occipital sulcus and preoccipital
notch.

8. LATERAL SULCUS
• Stem of the sulci
begins as a deep cleft
on the inferior surface
of the cerebral
hemispheres at the
anterior perforated
substance
• On reaching the
superolateral surface
it divides into three
rami.

9. Superolateral surface
Begins at the
superomedial border just
about one cm behind the
midpoint between
frontal & occipital poles
Lower end above the
posterior ramus of lateral
sulcus
CENTRAL SULCUS OF
ROLANDO

10. Calcarine sulcus
below the posterior end of the
corpus callosum and follows an
arched course
Parieto-occipital
sulcus
at the midpoint of the calcarine
sulcus and courses upwards and
backwards to cut the
superomedial border in front of
the occipital pole

11. FRONTAL LOBE
• Precentral sulcus – in
front and parallel to the
central sulcus
• Superior and inferior
frontal sulci – extend
forward from precentral
sulcus
• Four gyri – precentral
gyrus & superior, middle,
inferior frontal gyri
• Precentral gyrus continues
with paracentral lobule at
medial surface

12. INFERIOR FRONTAL GYRUS
•pars orbitalis:
below anterior
horizontal ramus of
lateral sulcus
• pars triangularis:
between anterior
horizontal and
anterior ascending
rami
• pars posterior:
behind anterior
ascending ramus

13. PARIETAL LOBE
• Postcentral sulcus –
behind and parallel to
the central sulcus
• Intraparietal sulcus –
extends backwards :joins
transverse occipital sulcus
• divides the rest of the
parietal lobe into superior and
inferior parietal lobule.
• Postcentral gyrus also
continuous with posterior
paracentral lobule

14. PARIETAL LOBE
• Superior Parietal lobule
(gyrus) : above the
intraparietal sulcus
• Inferior parietal lobule
(gyrus) : below the
intraparietal sulcus.
• In lobule, Supramarginal
gyrus arching over posterior
ramus of lateral sulcus and
• Angular gyrus over
superior temporal sulcus

15. TEMPORAL LOBE
• superior surface of the
superior temporal gyrus
presents two
transverse temporal
gyri
•The anterior transverse
temporal gyrus is called as
the Heschl’s gyrus which
forms the primary auditory
area of the cortex

16. OCCIPITAL LOBE
• Lunate sulcus – in
front of occipital lobe
• Lateral occipital
sulcus in front of
lunate sulcus
• Superior and inferior
occipital gyri
• Transverse occipital
sulcus–behind the
parieto-occipital sulcus

17. • Cingulate
sulcus
• Cingulate
gyrus
• Callosal
sulcus

18. • Between the cingulate
sulcus and the
superomedial border of
the hemisphere. Two parts
• A small part around the
upper part of the central
sulcus, theparacentral
lobule
• A large medial part, the
medial frontal gyrus

19. • Cuneus: triangular area
between the posterior part
of the calcarine sulcus
and the parieto- occipital
sulcus
• Isthmus: between the
splenium and calcarine
sulcus
• Precuneus:
quadrangular area
between the parieto-
occipital sulcus and
paracentral lobule
• Anteriorly the lingual gyrus is
continued as the
parahippocampal gyrus

20. On the orbital part of the inferior
surface :
Anterior end of the PHG gyrus hooks
sharply backwards (limited laterally
by a short rhinal sulcus)
This hook like anterior end of the
PHG is called uncus.
• Olfactory sulcus
• Orbital sulcus : divides the rest
of the orbital surface into anterior,
posterior, medial and lateral orbital
gyri.
INFERIOR SURFACE