1. Brain Topography

2. Cerebrum
The largest division of the forebrain. It is divided into two hemispheres, each of which is divided into four lobes.
Cerebrum
Cerebellum

3. Corpus callosum
Divided into two halves, the cerebral hemispheres, which are separated by a deep Median longitudinal fissure which lodges a dural fold called falx cerebri.
In the depth of the fissure, the hemispheres are connected by a bundle of fibers called the corpus callosum.
Left hemisphere
Right hemisphere
Median Longitudinal fissure

4. The structure of cerebral hemispheres includes:
Superficial layer of grey matter, the cerebral cortex.
Deeper to the cortex, axons running to and from the cells of the cortex form an extensive mass of white matter (WM).
Burried within the white matter lie a number of nuclear masses (caudate, putamen, globus pallidus) collectively known as the basal ganglia.
The cavity of hemisphere is called the lateral ventricle.
Cortex
Basal ganglia WM
Lateral ventricle

6. Cerebral Cortex
The outermost layer of gray matter making up the superficial aspect of the cerebrum.
Cerebral Cortex

7. Cerebral Features Gyri – Elevated ridges “winding” around the brain.
Sulci – Small grooves dividing the gyri
Central Sulcus – Divides the Frontal Lobe from the Parietal Lobe
Highly convoluted arrangement. This arrangement maximize the surface area of the cerebral cortex (about 70% is hidden within the depths of sulci).
Fissures – Deep grooves, generally dividing large regions/lobes of the brain
Longitudinal Fissure – Divides the two Cerebral Hemispheres
Transverse Fissure – Separates the Cerebrum from the Cerebellum
Sylvian/Lateral Fissure – Divides the Temporal Lobe from the Frontal and Parietal Lobes

8. Gyri (ridge)
Sulci (groove)
Fissure
(deep groove)

9. Specific Sulci/Fissures:
Central Sulcus
Longitudinal Fissure
Sylvian/Lateral Fissure
Transverse Fissure

10. Three sulci, consistent in their position (central, lateral & parieto-occipital) are used to divide each hemisphere into lobes.
Each hemisphere is divided into FOUR lobes (named after overlying bones).
reception and evaluation of sensory information
motor function, motivation, aggression, smell and mood
visual processing
smell, hearing, memory and abstract thought

11. Lobes of the Brain (4) Frontal Parietal Occipital Temporal
* Note: Occasionally, the Insula is considered the fifth lobe. It is located deep to the Temporal Lobe.

12. Lobes of the Brain - Frontal
The Frontal Lobe of the brain is located deep to the Frontal Bone of the skull.
It plays an integral role in the following functions/actions:
- Memory Formation
- Emotions
- Decision Making/Reasoning
Personality
In addition to its major role in motor functions

13. Frontal lobe Precentral gyrus.
Superior & inferior frontal sulci divide the lobe into superior, middle & inferior frontal gyri.

14. Frontal Lobe
Premotor cortex: Located in the region immediately anterior to the precentral gyrus (Brodmann’s area 6).
Primary motor cortex: Located in precentral gyrus (Brodmann area 4).
Prefrontal cortex: Extensive region of the frontal lobe anterior to premotor area.
Broca’s (motor speech) area: Located in the inferior frontal gyrus of the dominant hemisphere, usually left (Brodmann’s area 44 & 45).
Frontal eye field: Located in the middle frontal gyrus immediately in front of motor cortex (Brodmann’s area 8).

15. Gyri of the Frontal Lobe
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
] Broca’s area (dominant hemisphere)

16. Gyri of the Cerebral Cortex (Lateral Surface)

17. Gyri of the Cerebral Cortex (basal surface) Basal Surface Rectus Gyrus
Orbital Gyrus
Inferior Frontal Gyrus

18. Gyri of the Cerebral Cortex (Medial Surface)
Medial Frontal Gyrus
Paracentral Lobule

19. Lobes of the Brain - Parietal Lobe
The Parietal Lobe of the brain is located deep to the Parietal Bone of the skull.
It plays a major role in the following functions/actions:
- Senses and integrates sensation(s)
Spatial awareness and perception
(Proprioception - Awareness of body/ body parts in space and in relation to each other)

20. Parietal Lobe Parietal lobe: Postcentral gyrus.
Intraparietal sulcus dividing the lobe into superior & inferior parietal lobules.

21. Primary Somatosensory Cortex/ Postcentral Gyrus
Somatosensory Association Cortex
Primary Gustatory Cortex

22. Parietal Lobe
Primary Somatosensory Cortex (Postcentral Gyrus) – Site involved with processing of tactile and proprioceptive information.
Somatosensory Association Cortex - Assists with the integration and interpretation of sensations relative to body position and orientation in space. May assist with visuo-motor coordination.
Primary Gustatory Cortex – Primary site involved with the interpretation of the sensation of Taste.

23. Parietal lobe
Primary somatosensory cortex: located in postcentral gyrus (Brodmann’s area 1, 2, 3).
Parietal association cortex: located posterior to primary somatosensory cortex.

24. Gyri of the Parietal Lobe
Lateral Surface
Postcentral Gyrus ----
Superior Parietal Lobule
Inferior Parietal Lobule ---- Wernicke’s area ??
Supramarginal Gyrus
Angular Gyrus
Medial Surface
Paracentral Lobule
Precuneus

26. Lobes of the Brain – Occipital Lobe
The Occipital Lobe of the Brain is located deep to the Occipital Bone of the Skull.
Its primary function is the processing, integration, interpretation, etc. of VISION and visual stimuli.

27. Occipital Lobe
Primary Visual Cortex – This is the primary area of the brain responsible for sight -recognition of size, color, light, motion, dimensions, etc.
located on the medial surface of the hemisphere, in the gyri surrounding the calcarine sulcus (Brodmann’s area 17).
Visual Association Area – Interprets information acquired through the primary visual cortex. located around the primary visual cortex.

28. Primary Visual Cortex
Visual Association Area

29. Gyri of the Occipital Lobe
Lateral Surface:
Lateral Occipital Gyrus
Superior Occipital Gyrus
Inferior Occipital Gyrus
Medial Surface
Cuneus
Lingual Gyrus
Basal Surface
Occipitotemporal Gyrus

31. Lobes of the Brain – Temporal Lobe
The Temporal Lobes are located on the sides of the brain, deep to the Temporal Bones of the skull.
They play an integral role in the following functions:
Hearing
Organization/Comprehension of language
Information Retrieval (Memory and Memory Formation)

32. Superior, middle & inferior temporal gyri
Temporal lobe:
Superior & inferior temporal sulci giving rise to superior, middle & inferior temporal gyri.
Insula: the gyri in the depth of lateral fissure, covered by parts of frontal, parietal & temporal lobes called the opercula (removed in lower picture.).
sts
its
insula

33. Temporal Lobe
Primary Auditory Cortex – Responsible for hearing
located in the superior surface of the superior temporal gyrus (Brodmann’s area 41, 42)
Primary Olfactory Cortex – Interprets the sense of smell once it reaches the cortex via the olfactory bulbs. (Not visible on the superficial cortex)
Auditory association cortex: located immediately around the primary auditory cortex (also includes Wernick’s area)
Wernicke’s Area – Language comprehension. Located on the Left Temporal Lobe.

34. Primary Auditory Cortex
Wernike’s Area
Primary Olfactory Cortex (Deep)
Conducted from Olfactory Bulb

35. Temporal Lobe Parahippocampal gyrus:
located in the inferomedial part of temporal lobe.
Deep to this gyrus lies the hippocampus and the amygdala, which are parts of limbic system

36. Language Area Organized around the lateral fissure.
Broca’s area: concerned with expressive aspects of language.
Wernick’s area: responsible for comprehension of the spoken words.
Nearby regions of temporal lobe and parietal lobe (angular gyrus & supramarginal gyrus of the inferior parietal lobule) are important in naming, reading, writing, and calculation.

37. Arcuate Fasciculus - A white matter tract that connects Broca’s Area and Wernicke’s Area through the Temporal, Parietal and Frontal Lobes. Allows for coordinated, comprehensible speech. Damage may result in:
- Conduction Aphasia - Where auditory comprehension and speech articulation are preserved, but people find it difficult to repeat heard speech.
Arcuate Fasciculus

38. Gyri of the Temporal Lobe
Lateral Surface Superior Temporal Gyrus Middle Temporal Gyrus Inferior Temporal Gyrus Basal Surface Lingual Gyrus Occipitotemporal Gyrus Medial Occipitotemporal Gyrus Lateral Occipitotemporal

39. Parietal lobe Frontal lobe Occipital lobe Temporal lobe
Somatosensory cortex
(Somesthetic sensation and proprioception)
Supplementary motor area
(programming of complex movement)
Primary motor cortex
(Voluntary movement)
Premotor cortex
(coordination of complex
movements)
Central
sulcus
Posterior parietal cortex
(integration of somatosensory and visual input)
Prefrontal association cortex
(planning for voluntary activity; decision making;
personality traits)
Parietal lobe
Wernicke’s area
(speech
understanding)
Frontal lobe
Parietal-temporal-occipital
association cortex
(integraton of all sensory input-
imp in language)
Broca’s area
(speech formation)
Primary auditory cortex
Occipital lobe
Limbic association cortex
(motivation, emotion, memory)
Temporal lobe
Primary visual cortex

40. Lobes and Structures of the Brain
A. Central Sulcus
B. Frontal Lobe
C. Sylvian/Lateral Fissure
A. (groove) G.
D. Temporal Lobe B. F.
E. Transverse Fissure
F. Occipital Lobe
C. (groove)
G. Parietal Lobe E. D.
(groove)

42. Hemispheric Dominance
The localization of speech centers & mathematical ability is the criterion for defining the dominant cerebral hemisphere.
In 96% of normal right-handed individuals and 70% of normal left-handed individuals, the left hemisphere contains the language centers. These are left hemisphere dominant.
Cerebral dominance becomes established during the first few years after birth.
Verbal Memory
Shape Memory
Hemispheres communicate via the corpus callosum

43. White Matter Underlies the cortex and contains:
Nerve fibers, Neuroglia cells & Blood vessels.
The nerve fibers run in different directions and originate, terminate or sometimes both, within the cortex.

44. Depending on their origin & termination, the nerve fibers in the cerebral white matter are classified into three types: Association, Commissural & Projection
Association fibers: Unite different parts of the same hemisphere
Commissural fibers: Connect the corresponding regions of the two hemispheres
Projection fibers: Consisting of
Afferent fibers conveying impulses to the cerebral cortex.
Efferent fibers conveying impulses away from the cortex.

45. Association Fibers Unite different parts of the same hemisphere.
Are of two kinds:
Those connecting adjacent gyri, short association fibers
Those connecting more distant parts, long association fibers.
Short association fibers
Long association fibers

46. Long Association Fibers
Uncinate fasciculus: connects frontal to temporal lobe
Superior longitudinal fasciculus: connects the frontal, occipital, parietal, and temporal lobes
Arcuate fasciculus: connect gyri in frontal to temporal lobes
Inferior longitudinal fasciculus: connects occipital to temporal pole 2 5 3 1 4
5. Cingulum: connects frontal & parietal lobes to the para-hippocampal gyrus and adjacent temporal gyri

47. Commissural Fibers
Connect the corresponding regions of the two hemispheres.
Include:
Corpus callosum.
Anterior commissure.
Hippocampal commissure (commissure of fornix).
Posterior commissure.

48. Corpus Callosum
Connects the corresponding regions of the two hemispheres except the temporal lobes, that are connected by anterior commissure
It is shorter craniocaudally than is the hemisphere
The callosal fibers linking the frontal poles curve forward forming anterior forceps (forceps minor)
The callosal fibers linking the occipital poles curve backward forming posterior forceps (forceps major)
Anterior forceps F CC P O
Posterior forceps

49. Parts of Corpus Callosum
Body
Splenium
Genu
Rostrum

50. Anterior commissure: connects the inferior and middle temporal gyri & the olfactory regions of the two hemispheres
Posterior Commissure: connects the left and right midbrain. Important in the bilateral pupillary reflex
Hippocampal Commissure: connects the two hippocampi with each other

51. Projection Fibers Consist of:
Afferent fibers conveying impulses to the cerebral cortex.
Efferent fibers conveying impulses away from the cortex.
Deeper to the cortex, these fibers are arranged radially as the corona radiata.
Then the fibers converge downward, form internal capsule, between thalamus and basal ganglia.
Continue in the crus cerebri of the midbrain, basilar part of pons, & pyramid of medulla oblongata.
corona radiata
Internal capsule
crus cerebri
pyramid
pyramidal decussation
Corticospinal tract

52. Internal Capsule
Bundle of projection fibers, passes through the interval between the Thalamus (T) and the basal ganglia: Caudate (C) & Lentiform nucleus (L)
Has 5 parts:
1-Anterior limb: Thalamocortical & Frontopontine fibers
2-Genu: corticobulbar fibers
3-Posterior limb: Corticospinal, Corticobulbar & Thalamocortical fibers
4-Retrolenticular part: Geniculocalcarine fibers
5-Sublenticular part (not shown): geniculo-temporal fibers C 1 2 L 3 T 4