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The Brain Anatomy by Dr Arman Hossain

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Anatomy of Human Brain Presented by Dr Arman MD (Resident) Physical Medicine & Rehabilitation, Dhaka Medical College, Dhaka, Bangladesh. reference taken from latest book & journal.

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The Brain Anatomy by Dr Arman Hossain

  1. 1. Anatomy of Brain Dr SM Arman Hossain MD Resident (Phase-A) Department of Physical Medicine And Rehabilitation Dhaka Medical College
  2. 2. The Brain The human brain is by far the most complex & highly organized structure of the body. This organ allows us to think, move, feel, see, hear, taste, and smell. It controls our body, receives, analyzes, and stores information. produces electrical signals, which, together with chemical reactions, let the parts of the body communicate.
  3. 3. The Brain The adult human brain weighs on average about 1.2–1.4 kg (2.6– 3.1 lb), or about 2% of total body weight with a volume of around 1260 cm3 in men and 1130 cm3 in women. Despite this relatively small mass, the brain contains approximately 100 billion neurons. Functioning as a unit, these neurons make up the most complex and highly organized structure on earth.
  4. 4. Neuron Neurons (also known as nerve cell) are the basic units of the nervous system. Neurons are excitable cells that are specialized for the reception of stimuli and the conduction of the nerve impulse.
  5. 5. Types of the neurons (Snell NeuroAnatomy, Table 2-1) Types Site According to the number of processes 1. Unipolar • Dorsal root ganglion. 2. Bipolar • Retinal bipolar cells. • Cells of the sensory cochlear & vestibular ganglia 3. Multipolar • Fiber tracts of the brain and spinal cord. • peripheral nerves & motor cells of spinal cord According to the size of the neuron 1. Golgi Type 1(Long axon) • Purkinje cells of the cerebellar cortex • Motor cells of the spinal cord 2. Golgi Type 2 (Short axon) • Cerebral and cerebellar cortex
  6. 6. Neurons (Snell Neuroanatomy, Fig:2-1, 2-3)
  7. 7. Anatomical parts of brain (Snell Neuroanatomy, Table:1-2) Primary vesicle Primary Division Subdivision Adult Structure Neural canal Remnant Forebrain Prosencephalon Telencephalon • Cerebrum • Basal ganglia • Hippocampus Lateral ventricle Diencephalon • Thalamus • Hypothalamus • Pineal body • Infundibulum Third ventricle Midbrain Mesencephalon Mesencephalon • Crus cerebri • Tectum • Tegmentum Cerebral Aqueduct Hindbrain Rhombencephalon Metencephalon • Pons • Cerebellum Fourth Ventricle Myelencephalon • Medulla oblongata
  8. 8. Functional Parts of brain There are mainly 3 functional region of brain: • Motor areas • Sensory areas • Association areas
  9. 9. Structures of the cerebrum External Structure Internal Structure Longitudinal fissure Tentorium cerebelli Sulci/Sulcus Gyri/Gyrus Corpus callosum Grey matter White matter
  10. 10. Longitudinal fissure & Tentorium cerebelli. • It consists of two cerebral hemispheres (left and right) • cerebral hemispheres are separated by a longitudinal fissure containing sickle-shaped fold of dura mater called falx cerebri. • A second fold of dura mater seperates the cerebral hemispheres from the cerebellum & is called Tentorium cerebelli
  11. 11. Tentorium cerebelli Longitudinal fissure
  12. 12. Gyrus and Sulcus The superficial region of the brain is called the cortex.The surface is not smooth, it’s convoluted. Each bump on the surface of the cerebrum is called a Gyrus (ridges or elevations), and each shallow groove on the surface of the cerebrum is called a Sulcus (grooves or depressions)
  13. 13. Lateral View of Brain (Snell,fig:1-10)
  14. 14. Medial View of brain (Atlas of Human Aanatomy, f.h.Netter)
  15. 15. The main sulci are: Central sulcus – groove separating the frontal and parietal lobes. Lateral sulcus – groove separating the frontal and parietal lobes from the temporal lobe. The main gyri are: Precentral gyrus – ridge directly anterior to central sulcus, location of primary motor cortex. Postcentral gyrus – ridge directly posterior to central sulcus, location of primary somatosensory cortex. Superior temporal gyrus – ridge located inferior to lateral sulcus, responsible for the reception and processing of sound.
  16. 16. Corpus Callosum This is the area that is responsible for the right half of the brain communicating with the left half of the brain. If the corpus callosum was cut, there would be no communication between the right and left halves of the brain. • This is the area that is responsible for the right half of the brain communicating with the left half of the brain. • If the corpus callosum was cut, there would be no communication between the right and left halves of the brain.
  17. 17. Lobes of the Cerebrum The cerebral cortex is classified into four lobes, according to the name of the corresponding cranial bone that approximately overlies each part.
  18. 18. Frontal Lobe Lobes of the Cerebrum
  19. 19. Parietal Lobe Lobes of the Cerebrum
  20. 20. Temporal Lobe Lobes of the Cerebrum
  21. 21. Occipital Lobe Lobes of the Cerebrum
  22. 22. Frontal Lobe The frontal lobe is the area of the brain responsible for higher cognitive functions. These include:- • Personality • Emotional Control • Social behaviour • Contralateral motor control • Language • Micturation
  23. 23. Parietal Lobe The parietal lobe plays a role in- • Language • Calculation • Spatial orientation • Constructional skill Parietal lobe also contains a specialized area called Wernicke’s area that is responsible for matching written words with the sound of spoken speech.
  24. 24. Temporal Lobe The temporal lobe plays a role in: • Auditory perception • Verbal & non verbal memory • Smell • Balance • Language • Melody & pitch perception
  25. 25. Occipital Lobe The occipital lobe is at the rear of the brain and controls vision and recognition.
  26. 26. Cortical Lobe Function (Davidson, 23rd, Table:25-2)
  27. 27. Depiction of the homunculus A cortical homunculus is a distorted representation of the human body, based on a neurological "map" of the areas and proportions of the human brain dedicated to processing motor functions, or sensory functions, for different parts of the body.
  28. 28. Vasculature The blood supply to the cerebrum can be simply classified into 3 distinct paired arterial branches: Anterior Cerebral Arteries – branches of internal carotid arteries, supplying the anteromedial aspect of the cerebrum. Anterior cerebral Artery Middle cerebral Artery Posterior cerebral artery Lateral Brain
  29. 29. Vasculature Middle Cerebral Arteries – continuation of internal carotid arteries, supplying most of the lateral portions of the cerebrum. Posterior Cerebral Arteries – branches of the basilar arteries, supplying both the medial and lateral sides of the cerebrum posteriorly. Anterior cerebral Artery Middle cerebral Artery Posterior cerebral artery Medial Brain
  30. 30. Artery Supply of the cerebrum (Atlas of Human Anatomy, f.h.Netter)
  31. 31. Circle of Willis The circle of Willis lies in the interpeduncular fossa at the base of the brain. It is formed by the anastomosis between the two internal carotid arteries and the two vertebral arteries. The anterior communicating, anterior cerebral, internal carotid, posterior communicating, posterior cerebral, and basilar arteries all contribute to the circle
  32. 32. Circle of Willis
  33. 33. Clinical relevence
  34. 34. Clinical Relevance (Stroke) Stroke: Acute, focal brain dysfunction due to vascular disease is called stroke. Davidson 23rd, fig:26.1 A classification of stroke disease.
  35. 35. Clinical & radiological features of stroke syndrome (Davidson,23rd, Fig: 26.12)
  36. 36. Diencephalon Made of 3 parts mainly:- Thalamus Hypothalamus Epithalamus
  37. 37. Thalamus Thalamus means “inner room” in Greek, as it sits deep in the brain at the top of the brainstem. The thalamus is called the gateway to the cerebral cortex, as nearly all sensory inputs pass through it to the higher levels of the brain(cerebral cortex) Location- On each side of third ventricle
  38. 38. Nucleus & Functions of thalamus Nucleus of Thalamus
  39. 39. Functions of Thalamus • Sensory relay centre. • Crude centre for perception of sensation. • Arousal & alertness reaction. • Language. • Emotional aspect of behaviour. • Sexual sensation. • Reflex activity centre • Integration of Sensory impulses & Motor functions. Visceral & somatic function.
  40. 40. Clinical relevance Thalamic Hand The contralateral hand is held in an abnormal posture in some patients with thalamic lesions. The wrist is pronated and flexed, the metacarpophalangeal joints are flexed, and the interphalangeal joints are extended. The fingers can be moved actively, but the movements are slow. The condition is due to altered muscle tone in the different muscle groups.
  41. 41. Hypothalamus The hypothalamus is situated under the thalamus at the top of the brainstem. Although the hypothalamus is small, it controls many critical bodily functions: • Controls autonomic nervous system • Regulates body temperature • Regulates food intake Hypothalamus
  42. 42. Hypothalamus • Regulates water balance and thirst • Controls sleep-wake cycles • Functionally, the hypothalamus is part of the limbic system (which is involved in memories and emotions), so that’s why a painful memory can increase blood pressure, and a good memory can lower blood pressure. It is the Center for emotional response and behavior • The hypothalamus synthesizes and secretes hormones, and these in turn stimulate or inhibit the secretion of pituitary hormones & thus Controls endocrine system.
  43. 43. Basal ganglia Subcortical mass of grey matter strongly interconnected with cerebral cortex, thalamus & brainstem. forming important parts of extrapyramidal system Parts- 1. Corpus Striatum a. Caudate Nucleus b. Lentiform Nucleus 2. Amygdaloid Body 3. Claustrum Globus pallidus Putamen
  44. 44. Basal ganglia
  45. 45. Basal ganglia (Snell Neuroanatomy, Figure 7-15)
  46. 46. Main functional components of basal ganglia 1. Corpus Striatum a. Caudate Nucleus b. Lentiform Nucleus Corpus striatum receives information from :- Cerebral cortex, Thalamus, Subthalamus, brainstem, Substantia nigra 2. Subthalamic nucleus: receives information from brain areas 3. Substantia nigra :receives from globus pallidus & subthalamic nucleus.
  47. 47. Functions of basal ganglia 1. Basal nuclei control muscular movement by influencing the cerebral cortex & have no direct control of descending pathways.Thus influencing skill cortical motor activities like :- - Routine behavioure or habit - Cognition - Passing football - Drawing a diagram - Writing letters of the alphabet 2. Exerts inhibitory influence on a number of motor system. 3. Help prepare for the movement.
  48. 48. Disorders associated with basal ganglia 1. Hypokinetic disorder: - Parkinson’s disease 2. Hyperkinetic disorder: Disorder Area involved 1. Chorea Caudate nucleus • Huntington’s • Sydenham’s • Wilson’s disease 2. Athetosis Putamen 3. Ballismus (hemi) Subthalamic nucleus 4. Dystonia Putamen
  49. 49. Athetosis Slower writhing movement of the limb is called athetosis
  50. 50. Ballismus Ballistic movements of the limbs usually occurs unilaterally (Hemiballismus) in vascular lesion of subthalamic structure.
  51. 51. Chorea Jerky, small-amplitude, purposeless involuntary movement is called chorea.
  52. 52. Dystonia Involuntary painful sustain muscle spasm result in twisting and repetitive movements or abnormal fixed postures is called dystonia.
  53. 53. Parkinson’s disease Parkinsonism is a clinical syndrome characterised primarily by bradykinesia , with associated increased tone (rigidity), tremor and loss of postural reflexes. Degenerative changes in globus pallidus & substansia nigra with marked reduction of dopamin. Classical Triad: 1. Tremor (Resting tremor) 2. Rigidity (increased muscle tone) 3. Bradykinesia (Slowness of movement)
  54. 54. Clinical features of Parkinson’s disease • The motor symptoms are almost always initially asymmetrical. • features are initially unilateral, gradual bilateral involvement evolves with time • Unilateral rest tremor affecting limbs, jaw and chin. • Difficulties with rapid fine movement such as difficulties with fastening buttons, shaving or writing
  55. 55. Clinical features of Parkinson’s disease • Tiredness, mental slowness, increasingly small handwriting. • Slowness of gait • As the disease advances, speech becomes softer and indistinct • Other neuropsychiatric features (anxiety, depression, apathy, hallucinosis/psychosis).
  56. 56. Internal Capsule Afferent and efferent nerve fibers passing to and from the brainstem to the entire cerebral cortex must travel between large nuclear masses of gray matter within the cerebral hemisphere. At the upper part of the brainstem, these fibers form a compact band known as the internal capsule.
  57. 57. Boundary of Internal Capsule It is flanked medially by - • Caudate nucleus & Thalamus laterally by- • Lentiform nucleus Because of the wedge shape of the lentiform nucleus, as seen on horizontal section, the internal capsule is bent to form an anterior limb and a posterior limb, which are continuous with each other at the genu
  58. 58. Fibres passing through internal capsule
  59. 59. The Brainstem The brainstem is the most primitive part of the brain and controls the basic functions of life: breathing, heart rate, swallowing, reflexes to sight or sound, sweating, blood pressure, sleep, and balance. The brainstem can be divided into three major sections: 1. Midbrain 2. Pons 3. Medulla oblongata
  60. 60. Blood supply of the brainstem A. Midbrain- Posterior Cerebral artery. Superior Cerebellar artery. Basilar artery. B. Pons- Superior Cerebellar artery. Anterior Inferior Cerebellar artery. Basilar artery. C. Medulla Oblongata- Posterior inferior cerebellar artery. Basilar, Vertebral, Anterior and Posterior Spinal arteries
  61. 61. Blood supply of the brainstem (Atlas of human anatomy, fh.netter)
  62. 62. Midbrain (Atlas of human anatomy, fh.netter)
  63. 63. Midbrain at the level of Superior Colliculus (Snell Neuroanatomy, Figure 5-25)
  64. 64. Midbrain at the level of inferior Colliculus (Snell Neuroanatomy, Figure 5-25)
  65. 65. Transverse section of midbrain 1. Cranial nerve – 3, 4 2. Temporopontine & fronto pontine fibres 3. Corticospinal & corticonuclear fibres 4. Red nucleus 5. Medial & trigeminal lemniscus 6. Medical longitudinal fasiculus (MLF) 7. Substantia nigra
  66. 66. Pons Further down the brainstem is the pons, which relays sensory information between the cerebellum (for balance) and cerebrum (conscious awareness).
  67. 67. Transverse section of pons 1. Cranial nerve:- 5,6,7,8 2. MTSL M- Medial lemniscus (contains fibres from N. gracilis & N. cuneatus) T - Trigeminal lemniscus (contains fibres from N. of trigeminal nerve) S - Spinal lemniscus (contains fibres from lateral spinothalamic tract) L - Lateral lemniscus (part of auditory pathway fibes arise from cochlear n.) 3. Medical longitudinal fasiculus (MLF) 4. Reticular formation 5. Corticospinal & corticonuclear tract etc.
  68. 68. Medulla Oblongata At the base of the brainstem is the Medulla Oblongata, which contains the cardiac, respiratory, vomiting and vasomotor (blood vessel constriction) centers. It controls the nerves that effect the heart rate, blood pressure, and breathing. Damage here causes coma. Swelling from an injury causes pressure, which can damage this area, which can cause a coma.
  69. 69. Medulla Oblongata (Atlas of Human Anatomy, FH netter)
  70. 70. Transverse section of Medulla Oblongata 1. Cranial nerve – 9,10,11,12 2. Medial lemniscus 3. Corticospinal tract 4. Medical longitudinal fasiculus (MLF) 5. Reticular formation 6. Spinothalamic tract 7. Spinocerebeller tract etc.
  71. 71. Limbic system The limbic system is the area of the brain that regulates emotion and memory. It directly connects the lower and higher brain functions. Components: A. Cingulate gyrus B. Fornix C. Anterior thalamic nuclei D. Hypothalamus E. Amygdaloid nucleus F. Hippocampus & para hippocampus
  72. 72. Functions of the limbic system  FEARS (mnemonic) Fear, Food habit Emotion & Endocrine Anger Recent memory Sexual behaviour, Smell( Olfaction)
  73. 73. Reticular Formation The brainstem contains extensive fields of intermingled neuronal cell bodies and nerve fibres, which are collectively termed the reticular formation. Functions: • Arousal • Tonal Modulation • Pain Processing • Regulation of – Vomiting & Coughing – Respiration – Speech Functions
  74. 74. Clinical relevance Lesions in the brainstem: Lesion Vessel involved 1. Medial medullary syndrome Anterior spinal artery(Br of vertebral artery) 2. Lateral Medullary syndrome Posterior inferior cerebellar artery 3. Medial inferior pontine syndrome Basilar artery 4. Lateral inferior pontine syndrome Anterior inferior cerebellar artery
  75. 75. Medial Medullary Syndrome (Davidsons 23rd ) Occulsion or thrombus of the medullary branch of vertebral artery causes medial medullary syndrome. Features are: Ipsilateral Contralateral Paresis of the tongue which deviates toward the lesion (damage to cranial nerve XII) Hemiplegia (damage to corticospinal tract) with sparing of the face Loss of position and vibratory sensation (damage to medial lemniscus)
  76. 76. Lateral Medullary Syndrome (Wallenberg syndrome) Occlusion in the Posterior inferior cerebellar artery. Features: Ipsilateral Contralateral Limb ataxia (damage to inferior cerebellar peduncle and cerebellum) loss of pain and temperature on the body (damage to spinothalamic tract) Analgesia & thermoanesthesia of the face (damage to descending spinal tract and nucleus of cranial nerve V) Paralysis of palate, pharynx, and vocal cord (damage to nuclei or fibers of IX and X) with dysphagia and dysarthria Horner's syndrome (damage to descending sympathetic fibers) Vertigo, nausea, vomiting, and nystagmus (damage to vestibular nuclei)
  77. 77. Clinical relevance ( Bulbar & Pseudobulbar palsy) Bulbar palsy: Lower motor neuron lesion either at nuclear or fascicular level within the medulla or from bilateral lesions of the lower cranial nerves (9,10,11,12) outsie the brainstem is called bulbar palsy. Pseudobulbar palsy: Upper motor neuron lesions of the bulbar muscles from lesions of the corticobulbar pathways in the pyramidal tract is called pseudobulbar palsy
  78. 78. Cause of bulbar & Pseudobulber palsy (Davisons, 22nd, Table:26.30)
  79. 79. C/F of bulbar & pseudobulbar palsy Trait Bulbar palsy Pseudobulbar palsy Lesion LMNL of CN: 9,10,11,12 UMNL of CN: 9,10,11,12 C/F: Bulbar symptoms Dysarthria Dysphagia Tongue Wasted & fibrilating Spastic, small & stiff Speech Nasal Slow, slurred, indistinct Nasal Regurgitation Present Absent Jaw jerk Brisk Exaggerated (if the lesion is above pons) Palate Palatal paralysis Palatal & pharyngeal reflexes are exaggerated.
  80. 80. Horner’s syndrome Honrer’s syndrome occurs due to interruption of sympathetic pathway to the head & neck. Cause of Horner’s syndrome: • Paralysis of cervical sympathetic fibre • Bronchial carcinoma • Syringobulba ( Lesion in the brainstem) Features of Horner’s syndrome: • Miosis • Ptosis (partial) • Enopthalmus ( Shunken of the eyeball) • Squint ( Convergence) • Anhydrosis
  81. 81. Cerebellum • The cerebellum is situated in the posterior cranial fossa and is covered superiorly by the tentorium cerebelli. • It is the largest part of the hindbrain and lies posterior to the fourth ventricle, the pons, and the medulla oblongata • The cerebellum has two Hemispheres. They are connected by Vermis • Each hemisphere is divided into three main lobes: the anterior lobe, the Posterior lobe and the flocculonodular lobe • Cerebellum is functionally divided into 3 lobes: Paleocerebellum, neocerebellum, Archicerebellum.
  82. 82. Cerebellum
  83. 83. Cerebellum
  84. 84. Funtions of the cerebellum • Paleocerebellum (Spinal crebellum):Anterior lobe, uvula & pyramid of the vermis Function: Facilitate muscle tone & posture of the limb • Neocerebellum (Cerebro-ponto cerebellum): Middle lobe except uvula & pyramid. Function: Concerning with smooth performance of skilled act by co-ordinations of movement. • Archicerebellum (vestibular cerebellum): Flocculonodular lobe & lingula Functions: Maintaining equilibrium, tone & posture of trunk muscle
  85. 85. Blood Supply of cerebellum Blood Supply 1. Superior surface- Superior Cerebellar Artery 2. Inferior Surface- Anterior Inferior Cerebellar Artery & Posterior Inferior Cerebellar Artery The veins drain into neighboring venous sinuses.
  86. 86. Signs of Cerebellar Lesion Defect in posture Hypotonia Decrease muscle tone Defective attitude Turning of the face to the opposite side Vertigo Sensation like the surround environment is rotating Nystagmus Tremor of eyeball when viewing towards the same place Deep reflexes Pendular jerks
  87. 87. Signs of Cerebellar Lesion Defect in voluntarty movement Asthenia Weakness of the movement Ataxia Incoordinated movement Asynergia Incocodination between protogonist & antagonists Decomposition of movement Dysmetria Inability to arrest movement at desired point. Gait Reeling, legs wide apart deviated to the same side Disadidokinesia Cannot execute rapid & repeated movement. Intension tremor Tremor during movement
  88. 88. Venous drainage of the brain All veins drain into various cranial venous sinuses which in turn drain into internal jugular vein
  89. 89. Meninges of the brain Brain is very important but delicate organ. It is protected by following coverings: 1. Bony coverings of the cranium 2. Meninges 3. Cerebrospinal fluid (CSF)
  90. 90. Meninges of the brain Meninges are the membranes covering of brain & spinal cord. Composed of 3 layers: 1. Outer Dura mater (thickest) 2. Middle arachnoid mater 3. Inner pia mater
  91. 91. Cranial Meningeal Spaces • Epidural space: Potential space superior to dura. • Subdural space: Potential space between dura and arachnoid mater. • Subarachnoid space: Filled with CSF.Contains the blood vessels supplying brain
  92. 92. Ventricles of Brain The brain contains hollow spaces called ventricles, which are filled with CSF. They are extensive. Lateral ventricle is the largest, extends throughout the cerebrum. It is between the corpus callosum and the fornix. Third ventricle Lies medial to the thalamus. Fourth ventricle is at the base of the cerebellum; it is continuous with the central canal of the spinal cord, and also with the subarachnoid space. Cerebral aqueduct: connects the 3rd and 4th ventricles.
  93. 93. Ventricles of Brain (blue)
  94. 94. CerebroSpinal Fluid (CSF) CSF is a clear colorless fluid & is actively secreted ( major) , ultrafiltration (minor). CSF is formed by 1. Choroid plexus within the ventricles (50-70%) 2. Ependymal cells lining the ventricles 3. Perivascular space in the brain 4. Some of the fluid may originate from the brain substance Features: 1. Color: Crystal clear 2. Daily secretion: 550ml (0.3ml/min) 3. Volume: 150 ml 4. Specific gravity: 1.003-1.008 5. pH: 7.33 6. Osmolarity: 289 msom/kg H2O 7. Pressure: 50-180 mm of H2O
  95. 95. CSF pathway Foramen of luscka (lateral) Foramen of magendie (Median)
  96. 96. CSF Circulation in 3D Video
  97. 97. Function of CSF 1. Protective function: In air brain weight =1400 g, but in its water bath of CSF , brain weight = 50 g, making it suspended effectively & protects from the shock. 2. Distribution of peptides, hormones, neuroendocrine factors and other nutrients and essential substances to cells of the body. 3. Wash away waste products 4. Regulates the volume of the cranial content.
  98. 98. Functional part of the brain Functions of the brain: • Vision • Taste • Cognition • Emotion • Speech • Language • Hearing • Motor Cortex • Sensory Cortex • Autonomic Functions
  99. 99. Functional area of the brain according to lobe
  100. 100. Functional area of the cerebral cortex (Motor & Sensory)
  101. 101. Frontal Lobe Name of the area Number of the area Effect of lesion Primary motor area 4 Contra lateral paralysis & jacksonian fits Premotor area 6 Extrapyramidal effect Motor eye field area 6, 8, 9 Loss of horizontal conjugate movement of the eyeball Pre frontal Cortex 9, 10, 11, 12 Loss of orientation Brocha’s area 44, 45 Motor aphasia
  102. 102. Parietal Lobe Name of the area Number of the area Effect of Lesion Primary somesthetic (sensory) area 3, 1, 2 Contralateral sensory disturbances Somesthetic Association Area 5, 7 Contralateral Astereognosis and sensory neglect Sensory speech area 40, 39 Taste area 43
  103. 103. Temporal lobe The sensory speech area of Wernicke is localized in the superior temporal gyrus, with extensions around the posterior end of the lateral sulcus into the parietal region. The Wernicke area permits the understanding of the written and spoken language and enables a person to read a sentence, understand it, and say it out loud. Name of the area Number of the area Effect of Lesion Primary auditory area 42, 41 bilateral loss of hearing, but the loss will be greater in the opposite ear. loss of ability to locate the source of the sound Auditory Association Area 22 word deafness (acoustic verbal agnosia).
  104. 104. Occipital lobe Name of the area Number of the area Lesion Primary visual area 17 Contralateral Homonymous hemianopia Secondary visual area (Visual association area) 18, 19 loss of ability to recognize objects seen in the opposite field of vision
  105. 105. Vision The visual cortex resides in the occipital lobe of the brain. Sensory impulses travel from the eyes via the optic nerve to the visual cortex. Damage to the visual cortex can result in blindness.
  106. 106. Visual Pathway
  107. 107. Visual field defect
  108. 108. Hearing There are two auditory areas of the brain: • The primary auditory area (brown circle) is what detects sounds that are transmitted from the ear. It is located in the sensory cortex. • The auditory association area (purple circle) is the part of the brain that is used to recognize the sounds as speech, music, or noise.
  109. 109. Auditory Pathway (ECOLI MA) External Ear
  110. 110. Taste The gustatory complex (green circle) is the part of the sensory cortex (purple area) that is responsible for taste.
  111. 111. Language Wernicke’s area is a specialized portion of the parietal lobe that recognizes and understands written and spoken language. Wernicke’s area surrounds the auditory association area. Damage to this part of the brain can result in someone hearing speech, but not understanding it.
  112. 112. Emotion Emotions are an extremely complex brain function. The emotional core of the brain is the limbic system. This is where senses and awareness are first processed in the brain. Mood and personality are mediated through the prefrontal cortex. This part of the brain is the center of higher cognitive and emotional functions. Limbic System Prefrontal cortex
  113. 113. Alzheimer’s disease Alzheimer’s disease is the most common cause of dementia, but is rare under the age of 45 years. about 15% of cases are familial. Pathology: • macroscopically ,The brain in Alzheimer’s diseas is atrophic. particularly the cerebral cortex and hippocampus. • Histologically, presence of senile plaques and neurofibrillary tangles in the cerebral cortex. • Histochemical staining demonstrates significant quantities of amyloid in the plaques.
  114. 114. C/F of Alzheimer’s disease 1. The key clinical feature is impairment of the ability to remember information acquired from the past. 2. Association with disorders of other cortical functions. 3. Short-term and long-term memory are both affected, but defects in the former are usually more obvious. 4. Later in the course of the disease, typical features are- - Apraxia - Visuo spatial impairment - Aphasia 5. As the disease progresses it is common for patients to deny that there is anything wrong (anosognosia) 6. Depression is common.
  115. 115. References 1. BD Chaurasia's Human Anatomy. 6th edition. 2. Snell Clinical Neuroanatomy, 7th edition 3. Davidson's Principles and Practice of Medicine, 23rd edition. 4. Atlas of Human Anatomy, FH Netter.
  116. 116. Thanks for your patience listening
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Anatomy of Human Brain Presented by Dr Arman MD (Resident) Physical Medicine & Rehabilitation, Dhaka Medical College, Dhaka, Bangladesh. reference taken from latest book & journal.

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