CEREBRUM-SUMMARY_1.pptx

details of cerbrum

1. C E R E B R U M AND BASE OF THE SKULL

2. I N T R O DU CT IO N The cerebrum is the largest part of the brain with two hemisphere.The two cerebral hemisphere are linked by commisural fibres of corpus callosum. Each cerebral hemisphere contains externally highly convulated cortex of grey matter and internal mass of white matter or medulla . Each cerebral hemisphere contains lateral venticle continous with the third ventricle through interventricular foramen. The cerebral hemispheres contains motor and sensory areas and the limbic system. Each cerebral cortex is often divided phylogenetically into old allocortex,consisting of archicortex and paleocortex and a newer neocortex.

3. Longitudinal Fissure Cerebral hemisphere

4. Cortex and medulla

5. Surfaces of cerebral hemisphere Each cerebral hemisphere has three surfaces Superolateral surface Medial surface Inferior surface . Inferior surface further divided into two vi. Orbital surface vii.Tentorial surface

6. Surfaces of cerebral hemisphere………contd. Superolateral surface It follows the concavity of the cranial vault Medial surface It is flat and vertical and seperated from its fellow by the great longitudinal fissure and falx cerebri. Inferior surface Inferior surface or the basal surface is irregular and divided into orbital and tentorial surface.

7. Superolateral Medial surface Surfaces of the brain

8. Inferior surface Orbital surface Tentorial surface

9. Borders of cerebral hemisphere S u p er o m e d i a l b o r d er Inferior border

10. O cc i p i t a l po l e F r o n t a l p o l e T e m p o r a l p o l e Poles of the brain

11. Lobes of the brain F o u r l o b e s a r e present Frontal Parietal Occipital Temporal Occasionally insula is considered as the fifth lobe

12. Gyrus and sulcuses Each cerebral hemisphere convulation called Gyrus The gyruses are separated by furrows of varying length called Sulci. The convulated structure increases the cortical volume to three times what it would be if the surface is smooth. The area of the cerebral cortex is 2200cm² Sulci ( G r o o v e) Fissure (Deep groove) G yr i shows a complex pattern of (Elevation)

13. Important sulci and gyri In the suprolateral surface: ii. Lateral sulcus Deep cleft on the lateral and inferior surface It has a stem which divides into three rami:anterior,ascending,p- osterior. The floor of the posterior ramus is the insula which is hidden cortex. Lateral sulcus Central sulcus

14. Important sulcus and gyrus…….contd . ii. The central sulcus It is the boundary between frontal and parietal lobes It starts at the superomedial border, a little behind the midpoint between frontal and occipital poles.It runs downards and forwards for about 8-10cm to end little above the posterior ramus of lateral sulcus. It demarcates the motor and sensory area of the cerebral cortex. iii. The other known sulcuses are     superior frontal sulcus Inferior frontal sulcus Precentral sulcus Postcentral sulcus

15. Medial surface In the medial surface The commisural fibres of the corpus callosum lies in the depth of longitudinal fissure Parts of corpus callosum Rostrum Genu Trunk or body Splenium The anterior part divided into outer and inner zone by cingulate sulcus

16. splenium Genu Rostrum Medial surface with corpus callosum Body or trunk

17. C i ngu l a t e s u l c u s P a r i e t o - o cc i p i t a l s u l cus C a l ca r i n e s u l c us C o l l a t e r a l s u l c u s Sulcus in the medial surface

18. Sulcus and gyrus………contd. The posterior region of the medial surface is traversed by parieto-occipital and calcarine sulcus .The parieto- occipital sulcus marks the boundary between parietal and occipital lobes. The visual cortex lies above and below the calcarine sulcus. In the inferior cerebral surface Olfactory sulcus Rhinal sulcus Occipitotemporal sulcus Collateral sulcus

19. Orbital sulcus Occipitotemporal sulcus Collateral sulcus Rhinal sulcus Sulcus and important structures on inferior surface of cerebral hemisphere Olfactory sulcus

20. I n s ula -Present within the lateral sulcus Between temporal and frontal Lobe. -The overlying cortical areas are called opercula formed from the parts of frontal,temporal and parietal lobe -Functions linked to emotion and body’s homeostasis -i.e perception,motor control,self awarness,congnitive functioning interpersonal experience I n s u la

21. Cerebral cortex Cerebral cortex is an intricate blend of nerve cells and fibres,neuroglia and blood vessels. Microscopically the cortex consists of six layers or laminae lying parallel to the surface. From outside to inside IV.Molecular or plexiform layer V. The external granular layer VI.External pyramidal lamina VII.Internal granular layer VIII.Internal pyramidal cell layer I X. Mul t if o rm o r pl e i o mo r p h i c la y e r

22. P y r a m i d a l c e l l s

23. Neocortex has 6 layers designated I, II, III, IV, V, VI Pyramidal cells predominate in layers III and V Granule cells in layers II and IV Pyramidal cells Granule cells C e r e b r a l cortex

24. Pyramidal cells have large apical dendrite and basal dendrites Axon projects downward into subcortical white matter; may have collaterals Pyramidal cell is the primary output neuron P Y R A M I D A L CELL

25. Pyramidal cell Pyramidal cell

26. Broadmann’s areas These areas were defined and numbered by korbinian broadmann The areas are based on the cortical cytoarchitectonic organisation of neurons Many of the broadmann’s areas are defined on neurological function coorelated closely to diverse cortical functions. For example Area 1,2,3 – primary somatosensory area Area 4 – Motor area Area 41,42 – Auditory area Area 44,45 – Broca’s area,etc

27. s h o u l d e r w r i s t h a n d f i n g e r s t h u m b e y e f a c e l i p s j a w t o n g u e s w a l l o w i n g c h e w i n g l e g s t o e s n e c k e l b o w t r u n k a n k l e h i p M o t o r C o r t e x s h o u l d e r f o r e a r m w r i s t h a n d f i n g e r s t h u m b e y e n o s e f a c e l i p s g u m s j a w t o n g u e p h a r y n x a b d o m e n l e g s f o o t t o e s g e n i t a l i a e l b o w t r u n k h i p S e n s o r y C o r t e x M A P P IN G O F S E N S O R Y A N D M O T O R A R E A S T O T H E B O D Y

28. P r i m ary M o t o r C or t ex ( P r e c e nt r a l G y rus) – C or t ica l sit e involved with controlling movements of the body. Broca’s Area – Controls facial neurons, speech, and language c o mpre h en s i o n . L o cat ed o n L e ft F r o n t a l L o be. Broca’s Aphasia – Results in the ability to comprehend speech, but the decreased motor ability (or inability) to speak and form words. Orbitofrontal Cortex – Site of Frontal Lobotomies Desired Effects: Diminished Rage Decreased Aggression Poor Emotional Responses * Possible Side Effects: Epilepsy Poor Emotional Responses Perseveration (Uncontrolled, repetitive actions, gestures, or words) Frontal lobes cortical regions Primary motor cortex Broca’s area Orbitofrontal cortex

29. Parietal lobe cortical areas Primary Somatosensory Cortex (Postcentral Gyrus) – Site involved with processing of tactile and proprioceptive information. Associated somatosensory area(7) 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. Primary gustatory area (40) Primary somatosensory area (3, 1, 2)

30. Primary Visual Cortex – This is the primary area of the brain responsible for sight -recognition of size, color, light, motion, dimensions, etc. Visual Association Area – Interprets information acquired through the primary visual cortex. O c c i p i t a l l o b e a n d c o r t i c a l r e g i o n s

31. White matter of cerebrum Consists of myelinated nerve fibres which are categorized on the basis of their course and connections B. Association fibres It links different cortical areas of the same hemisphere Two types v. Short association fibres They are entirely intracotical Some merely pass from one wall of the sulcus to othe r. viii.Long association fibres They are present in bundles Example: uncinate f a s c i c u lu s , c i n gu l um , s upe r i o r longitudinal fasciculus,etc

32. White matter of cerebrum………contd. A. Commissural(transverse) fibres Commisural fibres cross the midline,linking corresponding areas in the two cerebral hemisphere. The largest commissure is the corpus callosum . Other commisures are Anterior Posterior Habenular Commissure of the fornix .

33. White matter of cerebrum……..contd. • A. Projection fibres Projection fibres connect cerebral cortex with lower levels in the brain and spinal cord. Consists of both coticofugal and corticopetal fibres Corticofugal fibres converge from all directions to form corona radiata.Corona radiata continous with the internal capsule.

34. C or pu s c allo s um A nter io r com m i s s u r e Posterior c o mm is s u r e C o mm i ss u r e s o f b r a i n C om m is s u r e o f f o r nix Habenular c o mm i ssu r e

35. C T S C A N O F T H E B R A I N

36. CT scan of the brain showing a tumour in the right cerebral hemisphere CT scan of brain…….contd

37. M R I O F B R A I N

38. . A non-progressive disorder Caused by brain injury pre (70-80%), peri, or post natally Injure occurs before CNS reaches maturity Patients often have great potential masked by their connections C E R E B R A L P A L S Y Manifestation Malfunction of motor centers Postural and balance difficulties Normal life expectancy possible Early death respiratory

39. Spastic 52-70% of all CPs Hyperirritability of muscles Arms flexed, legs internally rotated Difficulty bending into a sitting position Difficulty with head control Postural difficulty May not have protective extension A t h e t o i d o r D y s k i n e t i c T y p e 25- 30% of CPs Uncontrollable writhing movements of opposing muscle groups All four extremities involved Neck and face involved Voluntary movements are flailing Difficulty uprighting and balancing Grimacing

40. Other types Tremors (rare form) of CP Rigid 5 -10% of CPs Flaccid (Hypotonicity) Mixed 15 - 40% of CPs 5 to 10 % Affects balance and coordination. They may walk with an unsteady gait with feet far apart, and they have difficulty with motions that require precise coordination, such as writing. Ataxic cerebral palsy

41. BASE OF THE SKULL

42. SKULL BASE Skull base boundaries : Upper surface of the ethmoid bone,orbital plate of the frontal bone upto the ethmoid bo ne Key bones: Orbital Plate of frontal bone Ethmoid bone Sphenoid bone Occipital bone

43. Skull base……contd. Divided into three cranial fossa: Anterior cranial fossa M i d d l e c r a n i al f o s sa Posterior cranial fossa

44. Key openings in base of the skull Foramen spinosum Foramen ovale Foramen lacerum Foramen rotundum Foramen magnum Jugular foramen Superior orbital fissure Inferior orbital fissure Optic canal Hypoglossal canal Pterygopalatine fossa Skull base……contd.

45. Foramen rotundum Pr e s e n t at th e an te r i o r and medial part of sphenoid bone. Structures passing d.Maxillary nerve e.Emissary veins

46. Foramen ovale Located in the anterior part of sphenoid bone,posterolateral to foramen rotundum Structures passing Mandibular nerve Accessory meningeal artey Lesser petrosal nerve Emissary veins

47. Foramen spinosum Foramen spinosum may be absent in 2% of the cases. Situated posterolateral to foramen ovale Transmits following structures Middle meningeal artery Nervous spinosus from mandibular nerve Middle meninigeal vein

48. Foramen magnum Latin ”great hole” is present in the occipital bone It transmits Medulla oblong a ta, v ertebral arteries Anterior and Posterior spinal arteries Spinal accessory nerve Membrana tectoria,Alar ligaments.

49. Superior Orbital Fissure CN III, IV, V 1 , VI Middle meningeal artery- orbital branch Recurrent meningeal artery Superior opthalmic vein Jugular foramen Anterior compartment Inferior petrosal sinus  •  • • intermediate compartment Cranial nerve IX,X,XI Posterior compartment Internal jogular vein Meningeal branches of occipital and ascending pharyngeal artery