1. Anatomy of the cerebral hemispheres
Dr. Mohammed Abuelnour
اسم ورقم المقرر – Course Name and No.
6/30/2019

2. At the end of the lecture, the students should be able to:
Objectives:
At the end of the lecture, the students should be able to:
Describe the cerebral hemispheres: shape, surfaces and subdivision into lobes
Identify the important sulci and gyri of each lobe
Describe the internal structure of each hemisphere: cortex (grey matter), medulla (white matter), basal ganglia, lateral ventricle
Describe the functional areas of the cerebral cortex.
Describe different types of fibers in the hemisphere and their functions
اسم ورقم المقرر – Course Name and No.
6/30/2019

3. Cerebrum Largest part of the forebrain
Corpus callosum
Cerebrum
Largest part of the forebrain
Divided into two halves, the cerebral hemipheres
The two hemispheres are separated by a deep median longitudinal fissure .
the hemispheres are connected by the corpus callosum
Left hemisphere
Right hemisphere
Median longitudinal fissure
اسم ورقم المقرر – Course Name and No.
6/30/2019

4. The surface of each hemisphere are numerous FOLDS.
These folds are separated by grooves to increase the Surface Area of the Cerebrum. The folds are called GYRI, and the grooves are called SULCUS.

5. SURFACES Superolateral Surfaces: Medial Inferior
Each hemisphere has
3 surfaces, 4 borders,
4 Lobes.
Surfaces:
Lateral or superolateral: Convex and related to the skull.
Medial:
Flat & vertical and related to the falx cerebri & median longitudinal fissure.
Inferior:
Divided into orbital and tentorial parts by the of lateral sulcus.
Superolateral
Medial
Inferior
اسم ورقم المقرر – Course Name and No.
6/30/2019

6. BORDERS
Four borders:
1- Medial or Superomedial border: Between lateral & medial surfaces.
2- Inferolateral border: Between lateral & inferior surfaces.
3- Inferiomedial border:
Between inferior & medial surfaces.
اسم ورقم المقرر – Course Name and No.
6/30/2019

7. Three sulci, are used to divide each hemisphere into lobes.
These include:
Central sulcus & Lateral sulcus on the superolateral surface
Parieto-occipital sulcus, on the medial surface

8. Central sulcus
Separates the frontal lobe from parietal lobe
Lateral sulcus
Separates the temporal lobe from the frontal and parietal lobes
Parieto-occipital sulcus
Separates the occipital lobe from the parietal lobe on the medial surface F P T F P O

9. Medial Surface Sulci: Parietooccipital , Calcarine, Cingulate Gyri:
Cingulate, Parahippocam pal
اسم ورقم المقرر – Course Name and No.
6/30/2019

10. Each hemisphere is divide into FOUR lobes (named after overlying bones)
motor function, motivation, aggression, smell and mood
reception and evaluation of sensory information
visual processing
smell, hearing, memory and abstract thought

11. Frontal lobe: Precentral gyrus
Superior & inferior frontal sulci divide the lobe into superior, middle & inferior frontal gyri
Parietal lobe:
Postcentral gyrus
Intraparietal sulcus dividing the lobe into superior & inferior parietal lobules
Superior , middle & inferior frontal gyri
Precentral gyrus
Postcentral gyrus
sfs
ifs
Inferior parietal lobule
Superior parietal lobule
Intraparietal sulcus

12. The gyri in the depth of lateral fissure,
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,
sts
its
insula

13. Frontal Lobe Functional Areas of the Cerebral Cortex
Primary motor cortex
Located in precentral gyrus (Brodmann area 4)
Controls voluntary, skilled movements

14. Premotor cortex
(Brodmann’s area 6)
On the lateral surface, this includes the posterior parts of superior, middle and inferior frontal gyri
On the medial surface, it includes region of supplementary motor cortex.

15. Frontal eye field
Located in the middle frontal gyrus (Brodmann’s area 8)
Controls voluntary conjugate deviation of the eyes .
Damage to this area results in conjugate deviation of the eyes toward the side of lesion

16. Broca’s (motor speech) area
Located in the inferior frontal gyrus of the dominant hemisphere (usually left)
Brodmann’s area 44 & 45
Involved in language functions
Interconnected with parts of ipsilateral temporal, parietal and occipital lobes

17. Prefrontal cortex
Extensive region of the frontal lobe anterior to premotor area
Has cognitive functions of high order e.g. intellectual, judgemental and the planning of behaviour

18. Parietal lobe Primary sensory cortex
Located in postcentral gyrus (Brodmann’s area 1, 2, 3)
It is the final relay station for general sensations to a conscious level
اسم ورقم المقرر – Course Name and No.
6/30/2019

19. Parietal association cortex
Located posterior to primary sensory cortex
Superior parietal lobule responsible for:
Interpretation of general sensory information
Conscious
Inferior parietal lobule between somatosensoryy cortex and the visual & auditory cortices (and speech area in dominant hemisphere)

20. Temporal Lobe Primary auditory cortex
Located in the superior temporal gyrus (Brodmann’s area 41, 42)
Responsible for perception of sound
There is bilateral, representation of the cochlear duct
اسم ورقم المقرر – Course Name and No.
6/30/2019

21. Auditory association cortex
Located posterior to the primary auditory cortex
It is called Wernick’s area in dominant hemisphere
Plays major role in understanding of the spoken words.

22. 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

23. Responsible for visual perception
Occipital Lobe
Primary visual cortex
Located on the medial, in the gyri surrounding the calcarine sulcus (Brodmann’s area 17)
Responsible for visual perception
Upper half of visual field represented below the calcarine sulcus, and the lower half above the sulcus

24. Visual association cortex
Responsible for the interpretation of visual images
Lesion results in deficits in visual interpretation and recognition

25. Organized around the lateral fissure
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

26. The structure of cerebral hemipheres includes:
Superficial layer of grey matter, the cerebral cortex
Deeper to the cortex, an extensive mass of white matter
within the white matter lie a number of nuclear masses known as the basal ganglia
Cortex
Basal ganglia WM WM

27. White Matter Underlies the cortex Contains: Nerve fibers Neuroglia
Blood vessels
The nerve fibers originate, terminate or sometimes both, within the cortex

28. Depending on their origin & termination, these nerve fibers are classified into three types:
Association
B. Projection
C. Commissural

29. Association Fibers connect different parts of the same hemisphere
Are of two kinds:
Short association fibers: those connecting adjacent gyri,
Long association fibers: those connecting more distant gyri
اسم ورقم المقرر – Course Name and No.
6/30/2019

30. Connect the corresponding regions of the two hemispheres
Commissural Fibers
Connect the corresponding regions of the two hemispheres
Include:
Corpus callosum
Anterior commissure
Hippocampal commissure (commissure of fornix)
*(Posterior commissure, not a cerebral commissure)
Corpus Callosum F P
اسم ورقم المقرر – Course Name and No.
6/30/2019

31. Projection Fibers Fibers running vertically through the hemispheres
Consist of:
Cortical afferent fibers conveying impulses to the cerebral cortex: (mainly thalamo-cortical fibers)
Cortical efferent fibers carrying impulses away from the cortex to the lower centers:, corticobulbar, corticopontine, corticospinal, & descending autonomic fibers)
اسم ورقم المقرر – Course Name and No.
6/30/2019

32. Internal Capsule BG
Bundle of projection fibers, passes through the interval between the thalamus and the basal ganglia Th
6/30/2019

33. References
Clinical Neuroanatomy for Medical Students, Richard S. Snell-6th Edition.
Clinical Neuroanatomy and related neuroscience. M.J.T. FitzGerald, Jean Folan-Curran, Fourth Edition.