The document discusses the anatomy and functional areas of the cerebral cortex. It describes the main cerebral sulci and gyri, as well as the primary motor areas, sensory areas, and psychical areas. The primary motor area controls voluntary movement, while sensory areas include the primary somesthetic, visual, and auditory areas. Speech functions are performed by sensory and motor speech centers located in the dominant hemisphere.

1. Lecture by
Dr.N.Mugunthan.MBBS.,MS.,DNB.,MNAMS.,PhD.,MBA (Hosp.Adm.).,
Associate Professor
MGMC&RI

2. Learning objectives
1. Sulci
2. Gyri
3. Functional areas
a) Motor areas
b) Sensory areas
c) Psychical areas
4. Effects of lesions of functional areas
©Dr.N.Mugunthan

3. Cerebrum
Presenting parts:
Each cerebral hemisphere has
• 3 poles
• 3 surfaces
• 3 borders
• 6 lobes
©Dr.N.Mugunthan

4. 3 poles:
1. Frontal pole
2. Occipital pole
3. Temporal pole
(primitive post.pole)
Cerebrum cont…
FP
OPTP
©Dr.N.Mugunthan

5. 3 surfaces:
1. Superolateral surface
2. Medial surface
3. Inferior surface
a) Orbital surface
b) Tentorial surface
Cerebrum cont…
©Dr.N.Mugunthan

6. 3 borders:
1. Superomedial border
2. Inferolateral border (ant.1/3
- superciliary border)
3. Inferomedial border
(ant.1/3-medial orbital
border, middle 1/3 -
hippocampal border, post
1/3 – medial occipital
border)
Cerebrum cont…
©Dr.N.Mugunthan

7. 6 lobes:
1. Frontal lobe
2. Parietal lobe
3. Temporal lobe
4. Occipital lobe
5. Insular lobe (Island of
Reil)[sperolateral
surface]
6. Limbic lobe [medial
surface]
Cerebrum cont…
©Dr.N.Mugunthan

8. Sulci & Gyri
Main cerebral sulci:
1. Lateral sulcus (Sylvius)
• Stem & 3 rami
(posterior, ascending
& anterior)
2. Central sulcus
(Rolando)
3. Parieto-occipital sulcus
4. Calcarine sulcus
©Dr.N.Mugunthan

9. Frontal lobe:
• Precentral sulcus
• Precentral gyrus
• Superior frontal sulci &
• Inferior frontal sulci
• Superior frontal gyrus
• Middle frontal gyrus
• Inferior frontal gyrus
Sulci & Gyri on superolateral surface
©Dr.N.Mugunthan

10. • Anterior & ascending
rami of lateral sulcus
divides the inf.frontal
gyri into 3 areas
a) Pars orbitalis
b) Pars triangularis
c) Pars opercularis
Sulci & Gyri on superolateral surface cont…
©Dr.N.Mugunthan

11. Parietal lobe:
• Postcentral sulcus
• Postcentral gyrus
• Intraparietal sulcus
• Superior parietal lobule
• Inferior parietal lobule
Sulci & Gyri on superolateral surface cont…
©Dr.N.Mugunthan

12. • The upturned ends of
post.ramus of lateral
sulcus, sup. & inf.
temp.sulcus extends into
inf.parietal lobule and
divides it into 3 parts
a) Supramarginal gyrus
b) Angular gyrus
c) Arcus temporo-
occipitalis
Sulci & Gyri on superolateral surface cont…
©Dr.N.Mugunthan

13. Temporal lobe:
• Superior temporal sulci &
• Inferior temporal sulci
• Superior temporal gyrus
• Middle temporal gyrus
• Inferior temporal gyrus
• Sup. surface of sup.temporal
gyrus has
• 2 transverse temporal gyrus
(ant. & post.)
• Ant.transverse temporal
gyrus (Heschl’s gyrus –
primary auditory area)
Sulci & Gyri on superolateral surface cont…
©Dr.N.Mugunthan

14. Occipital lobe:
• Lateral occipital sulcus
• Superior & inferior
occipital gyrus
• Lunate sulcus
• Calcarine sulcus
Sulci & Gyri on superolateral surface cont…
©Dr.N.Mugunthan

15. ©Dr.N.Mugunthan

16. Sulci & Gyri on the medial surface
• Callosal sulcus
• Cingulate sulcus
• Cingulate gyrus
• Medial frontal gyrus
• Paracentral lobule (higher
centre for micturition &
defecation)
• Ant.& post. parolfactory
sulcus
• Paraterminal gyrus
• Parolfactory gyrus
©Dr.N.Mugunthan

17. • Suprasplenial sulcus
• Parieto-occipital sulcus
• Calcarine sulcus
• Cuneus
• Precuneus
Isthmus –narrow region
between splenium &
calcarine sulcus
Sulci & Gyri on the medial surface cont…
©Dr.N.Mugunthan

18. Orbital part:
• Olfactory sulcus
• Gyrus rectus
• Orbital sulcus (H-shaped)
• Medial orbital gyrus
• Lateral orbital gyrus
• Anterior orbital gyrus
• Posterior orbital gyrus
Sulci & Gyri on the inferior surface
©Dr.N.Mugunthan

19. Tentorial part:
• Collateral sulcus (medial)
• Occipito-temporal sulcus
(lateral)
• Medial occipito-temporal
gyrus
• Lateral occipito-temporal
gyrus
• Rhinal sulcus
• Uncus
• Parahippocampal gyrus
• Lingual gyrus
Sulci & Gyri on the inferior surface cont…
©Dr.N.Mugunthan

20. Broadmann mapping
52 areas in cerebral
cortex
©Dr.N.Mugunthan

21. Types of cortical functional areas
3 Types of functional
areas
1. Motor areas
2. Sensory areas
3. Association areas
©Dr.N.Mugunthan

22. Primary motor area (area 4)
 Precentral gyrus
(superolateral surface)
 Motor homunculus
 Control voluntary
movements of
contralateral side
©Dr.N.Mugunthan

23. Effects of lesion – primary motor area
Contralateral Flaccid
paralysis –initially
↓DTR
+Ve Babinski sign
Moderate recovery of
function
©Dr.N.Mugunthan

24. Pre-motor area (area 6 & 8)
Area 6- skillful acts
(programming of
movements)
Upper part of area 6 –
writing centre
 Area 8 also known as
frontal eye field
(regulates voluntary
conjugate movements)
©Dr.N.Mugunthan

25. Supplementary motor area
 Continuation of area 6 on
medial surface
Function:
 control complex
movements
 Elicits an urge to move
Lesion :
 Akinesia
 UMN type paralysis
(conjoint lesion of primary
motor,premotor &
supp.motor area)
©Dr.N.Mugunthan

26. Pre-frontal area (areas 9 to 12)
 In front of premotor area
 Highly developed in
human
Functions:
 Regulates the depth of
feeling
 Abstract thinking
 Mature judgement
 Foresight & tactfulness
(Silent area of brain)
©Dr.N.Mugunthan

27. Sensory areas
1. Primary sensory area
2. Secondary sensory area
(only for somesthetic
senses)
3. Sensory association area
4. Higher association area
©Dr.N.Mugunthan

28. Primary sensory area
1. Somesthetic area
2. Visual area
3. Auditory area
©Dr.N.Mugunthan

29. Somesthetic area
Primary somesthetic area (area 3,1,2)
 Located in post central gyrus
(superolateral surface)
 Functions:
o Localises,analyses &
discriminates different
modalities of cutaneous
senses
(touch,pressure,position &
vibration senses)
o Sensory homunculus
(sensation are
somatotopically arranged)
o Lower part of post central
gyrus – taste centre (area43)
©Dr.N.Mugunthan

30. Paracentral lobule –
receives sense of
distension of bladder &
rectum
Primary somesthetic area – functions cont…
©Dr.N.Mugunthan

31. Secondary somesthetic area
(supplementary)
Upper lip of posterior
ramus of lateral sulcus
(lower part of pre & post
central gyrus)
Functions:
Receives pain sensation
Other modalities of
cutaneous sensation
©Dr.N.Mugunthan

32. Somesthetic association area (area 5,7)
Behind the post
central gyrus
(superior parietal
lobule – area 5,7)
©Dr.N.Mugunthan

33. Higher association area for somesthetic senses
(area 40)
Supramarginal gyrus
(area 40)
Richly connected with
area 5 & 7
Lesion: (area 40)
Tactile agnosia
(Astereognosis)
Tactile aphasia
©Dr.N.Mugunthan

34. Visual senses
1. Primary visual area
(area17)
2. Visual association area
(area 18 & 19)
3. Higher visual association
area (area 39)
©Dr.N.Mugunthan

35. Visual association area (area 18 &19)
Parastriate area (area
18)/ visual area-II and
Peristriate
area(area19)/visual area-
III
Function:
Area 18 & 19- occipital
eye field
(mediate conjugate
movements involuntarily)
18
19
19 18
©Dr.N.Mugunthan

36. Auditory senses
1. Primary auditory area
(area 41)
2. Auditory association area
(area42)
3. Higher auditory
association area (area22)
©Dr.N.Mugunthan

37. Psychical cortex
Anterior part of temporal
lobe(temporal pole)
Function :
Memory (present & past)
Dreams
Hallucination (auditory &
visual)
©Dr.N.Mugunthan

38.  Performed by left
cerebral hemisphere
(regardless of hand
preference)
 Hence left hemisphere-
dominant or talking brain
 Right hemisphere – non
dominant or mute brain
Speech function cont…
©Dr.N.Mugunthan

39. Dominant hemisphere has 4
speech centres (3 sensory &
1 motor centre)
Sensory speech area:
1. Area 22
(higher auditory association
area/ Wernicke’s area)
2. Area 39
(higher visual association
area)
3. Area 40
(higher association area for
somesthetic senses)
Speech function cont…
©Dr.N.Mugunthan

40. Motor speech centre:
4. Area 44 & 45 (Broca’s
area)
Speech centres (motor &
sensory) may be
transferred to right
hemisphere in child up to
6-8 years (in case of
cerebral injury)
Speech function cont…
45
44
©Dr.N.Mugunthan

41. Area 22,39,40 – receives
input from hearing,vision
,touch &proprioception
Information processed in
area 22 (post.part)
Projected to Broca’s area
thro’ arcuate fasciculus
Sensory speech centre cont…
©Dr.N.Mugunthan

42. Lesions of speech centre
 Lesion involving speech
centre (dominant
hemisphere) – aphasia
2 types:
1. Sensory aphasia
2. Motor aphasia
Conduct aphasia – lesion
of arcuate fasciculus
(fluent/comprehension
intact /repetition of
spoken language is
extremely difficult)
©Dr.N.Mugunthan

43. Main cerebral sulci:
1. Lateral sulcus (Sylvius)
• Stem & 3 rami
(posterior, ascending
& anterior)
2. Central sulcus
(Rolando)
3. Parieto-occipital sulcus
4. Calcarine sulcus
Summary
©Dr.N.Mugunthan

44. Summary
Functional areas :-
1. Motor areas
2. Sensory areas
3. Psychical areas
©Dr.N.Mugunthan

45. Motor areas :-
1. Primary motor area
2. Pre-motor area
3. Supplementary motor
area
4. Pre-frontal area
Summary cont…
©Dr.N.Mugunthan

46. Summary cont…
Sensory areas:-
1. Primary sensory area
2. Secondary sensory
area (only for
somesthetic senses)
3. Sensory association
area
4. Higher association
area
©Dr.N.Mugunthan

47. Summary cont…
Primary sensory areas:-
1. Somesthetic area
2. Visual area
3. Auditory area
©Dr.N.Mugunthan