2. • Sulcus : A sulcus is depression or fissure
in the surface of the brain. ( valleys )
• Gyrus : A gyrus is a ridge on the cerebral
cortex. It is generally surrounded by one
or more sulci ( hills )
11. • Frontal lobe:
Anterior region of hemisphere; anterior to
central sulcus, superior to sylvian fissure
• Parietal lobe:
Posterior region of hemisphere; posterior to
central sulcus, anterior to parietooccipital
sulcus
• Occipital lobe:
Posterior to parietooccipital sulcus
• Temporal lobe:
Inferior to sylvian fissure, anterior to
angular gyrus
16. frontal lobe
The frontal lobe constitutes the entire region
in front of the central sulcus. Immediately
in front of the central sulcus lies the
precentral gyrus, which is the primary
motor region of the cerebral cortex. In
front of the precentral gyrus, the rest of
the frontal lobe is divided
into superior, middle and inferior frontal
gyri.
18. Frontal lobe gyrus
Lateral Surface
Precentral Gyrus --- primary motor area
Superior Frontal Gyrus
Middle Frontal Gyrus
Inferior Frontal Gyrus
Pars Opercularis
Pars Triangularis
Pars Orbitalis
Medial Surface
Medial Frontal Gyrus
Paracentral Lobule
Basal Surface
Rectus Gyrus
Orbital Gyrus ( superior, medial ,lateral ,inferior )
19.
20.
21.
22.
23. Parietal lobe
Behind the central sulcus, and above the
lateral fissure, lies the parietal lobe. Its
most anterior part is the postcentral
gyrus, which is the site of the primary
somatosensory cortex. Behind the
postcentral gyrus, on the lateral surface of
the hemisphere, the intraparietal
sulcus divides the rest of the parietal lobe
into superior and inferior parietal lobules.
30. Temporal lobe
The temporal lobe lies beneath the lateral
fissure. On its lateral surface the temporal
lobe is divided into three principal gyri
that run roughly parallel to the lateral
fissure: the superior, middle and inferior
temporal gyri. The superior temporal
gyrus includes the primary auditory
cortex.
36. Occipital lobe
The boundary between the parietal lobe and
occipital lobe is not coincident with a
single sulcus on the lateral surface of the
hemisphere; however, it is clearly marked
by the deep parieto-occipital sulcus on
the medial surface. The occipital lobe does
not bear any important landmarks on its
lateral surface but on the medial surface,
the prominent calcarine sulcus indicates
the location of the primary visual cortex.
37. Occipital lobe
Sulci:
• Superior occipital sulcus (extension of
intraparietal sulcus).
• Inferior occipital sulcus (extension of inferior
temporal sulcus).
Gyri:
• Superior occipital gyrus.
• Middle occipital gyrus.
• Inferior occipital gyrus
43. Limbic lobe
On the medial surface of the hemisphere, certain
portions of the frontal, parietal and temporal lobes
also constitute components of the limbic system.
Curving around the corpus callosum, and running
parallel to it, lies the cingulate gyrus , separated
from the rest of the hemisphere by the cingulate
sulcus. The cingulate gyrus passes posteriorly and
inferiorly round the posterior portion of the
corpus callosum to become continuous with
the parahippocampal gyrus of the temporal lobe.
Deep to the parahippocampal gyrus, within the
temporal lobe lies the hippocampus.
The cingulate gyrus, parahippocampal gyrus and
hippocampus are referred to as the limbic lobe.
48. Insular lobe
• Lies deep in floor of sylvian fissure,
overlapped by frontal, temporal and
parietal.
• The insular lobe is thought to be involved
in sensory and motor visceral functions as
well as taste perception.
55. Signs to identify sulcus in mri
• The midline sulcus sign: The longest
sulcus running horizontally and entering
the interhemispheric fissure is the central
sulcus .
• The M sign: The typical upper case M
shape of the inferior frontal gyrus is
formed by its parts ( orbitalis, triangularis,
and opercularis ).
56. signs
• The bifid post cg sign: Toward the
interhemispheric fissure, the postcentral
gyrus is medially fissured, enclosing the
pars marginalis of the cingulated sulcus
with both legs and thereby forming the
characteristic bifid post cg sign.
• The thin post cg sign: On the surface, the
precentral gyrus has a thicker
anteroposterior diameter compared with
the postcentral gyrus, which is thinner.
57. signs
• The handknob: defined the "handknob " as
1 single -shaped dorsally convex bulge of
the precentral gyrus.
• The upper T sign: The intersection of the
well-identifiable superior frontal sulcus
with the precentral sulcus has the shape of
an upper case T. The pre cg can be found
immediately posterior to this T shape.
58. signs
• The L sign: The sfg terminates in the pre
cg, which runs laterally from the posterior
end of the sfg, therefore together forming
an upper case L.
• The lower T sign: The inferior frontal
sulcus posteriorly terminates in the pre sc,
also in the shape of an upper case T that is
dorsally bordered by the pre cg.
59. signs
• Inverted omega sign : the central sulcus
more likely to have the shape of inverted
omega.
• The bracket sign: The bihemispheric
symmetric pars marginalis of the cingulate
sulcus forms an anteriorly opened bracket.
79. Superior frontal gyrus
Middle frontal gyrus
Superior frontal sulcus
Inferior frontal gyrus
Centrum semiovale
Central sulcus
Central sulcus
Postcentral sulcus
Postcentral sulcus
Supramarginal gyrus
Intraparietal sulcus
Angular gyrus
Parietooccipital sulcus
Superior parietal gyrus
NP/MGH
Precuneus
80. Superior frontal gyrus
Middle frontal gyrus
Superior frontal sulcus
Central sulcus
Central sulcus
Supramarginal gyrus
Postcentral sulcus
Intraparietal sulcus
Angular gyrus
Pars marginalis
Intraparietal sulcus
Superior parietal gyrus
NP/MGH
83. Superior Frontal gyrus
Forceps
minor
Superior Frontal sulcus
Middle Frontal gyrus
Inferior Frontal gyrus
Lateral orbital sulcus
Medial Orbital gyrus
Lateral orbital gyrus
Gyrus rectus
Anterior Orbital gyrus
Olfactory Sulcus
NP/MGH
84. Circular insular sulcus Cingulate gyrus
Superior Frontal
gyrus
short insular gyrus
Middle Frontal gyrus
Inferior Frontal sulcus
Inferior Frontal gyrus
pars opercularis
Sylvian Fissure
Posterior Orbital gyrus
Middle Temporal gyrus
Olfactory Sulcus
Superior Temporal gyrus
Inferior Temporal gyrus
NP/MGH
Gyrus rectus
Medial Orbital gyrus
85. Superior Frontal sulcus
Superior Frontal
gyrus
Cingulate sulcus
Middle Frontal gyrus
Precentral
sulcus
Precentral gyrus
Sylvian Fissure
Superior Temporal
gyrus
Superior Temporal Sulcus
Middle Temporal gyrus
Amygdala
NP/MGH
Anterior commissure
Inferior Temporal gyrus
86. Superior Frontal
gyrus
Middle Frontal gyrus
Central Sulcus
Superior Temporal gyrus
Hippocampus
Middle Temporal
gyrus
Inferior Temporal gyrus
Parahippocampal gyrus
CA1, cornu ammonis
NP/MGH
Fusiform gyrus