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19-Functions of Cerebral Hemisphere.Pdf Te xt Lecture . Important No.19 . Formulas . Numbers “The One Who Falls And Gets Up Is So . Doctor notes Much Stronger Than The One Who Never . Notes and explanation Fell” 1 Function of Cerebral hemisphere Objectives: 1- Students will be able to describe the general structure of the Cerebrum and Cerebral Cortex. 2- Students will be able to identify the Cerebrum, the Lobes of the Brain, the Cerebral Cortex, and its major regions/divisions. 3- Students will be able to describe the primary functions of the Lobes and the Cortical Regions of the Brain. 2 Introduction ONLY IN MALES’ SLIDES Cerebrum is the largest division of the brain. It is divided into two • The cerebrum is the largest part hemispheres, each of which is divided into four lobes. of the brain with two hemisphere, linked by commissural fibres of corpus callosum. • Each cerebral hemisphere contains externally highly convoluted cortex of grey matter and internal mass of white matter cerebrum or medulla. • The cerebral hemispheres cerebrum contains motor and sensory areas and the limbic system. cerebellum 3 ONLY IN FEMALES’ SLIDES Phineas Gage In 1848 in Vermont, had a 3.5-foot long, 13 lb. metal rod blown into his skull, through his brain, and out of the top of his head. Gage survived. In fact, he never even lost consciousness. Friends reported a complete change in his personality after the incident. He lost all impulse control. 4 ONLY IN FEMALES’ SLIDES Overview of the brain Component of the brain Cerebellum Telencephalon Diencephalon Brainstem Basal Cerebrum Hypothalamus Thalamus Medulla Pons Midbrain Ganglia mainly a relay collection of contains station for grey matter center for sensory situated inside autonomic pathways in the cerebral and endocrine their way to hemispheres control the cerebral cortex 5 ONLY IN FEMALES’ SLIDES Cont. The term “ brainstem ” is actually an anatomic rather than physiologic term, because it is easier , in terms of anatomy, to group “ all CNS structures that hang between the cerebrum and spinal cord “ together. However, in terms of Physiology,the situation is more complicated, because brainstem structures are involved in many diverse & different bodily functions: Respiratory , Regulation of it contain several Balance ( Vestibular Cardiovascular and consciousness Cranial Nerve nuclei nuclei ) Gastrointestinal wakefulness and sleep control Most people ( about 90 %) have the left cerebral hemisphere dominant , and are therefore right-handed. The remaining (around 10 % ) of the population usually have their right hemisphere dominant, and are therefore left-handed. The frontal lobe of the dominant hemisphere contains Broca’s area (the area for production of speech). Therefore, if a right-handed person gets a stroke involving his left cerebral hemisphere , he is likely to have right-sided hemiplegia (paralysis) and aphasia (loss of the power of speech). 6 ONLY IN FEMALES’ SLIDES Cerebral cortex Cerebral cortex is the outermost layer of gray matter making up the superficial aspect of the cerebrum. Cerebral features Elevated ridges “winding” around the Gyri Brain. Sulca Small grooves dividing the gyri Divides the frontal lobe Central sulcus From the parietal lobe Deep grooves, generally dividing large regions / Fissures lobes of the brain Longitudinal fissures Divides the two cerebral hemispheres Transverse fissure Separates the cerebrum from the cerebellum Divides the temporal lobe from the frontal and Sylvian/lateral fissure parietal lobes 7 ONLY IN FEMALES’ SLIDES Cont. Gyri Real sulci "ridge" Sulci “groove” Fissure “deep groove” Real sulci Longitudinal fissure Real sulci 8 ONLY IN MALES’ SLIDES Cerebral cortex layers Microscopically the cortex consist of six layers or lamina parallel to the surface From outside to inside the layers are: VI-Layer of V-large II-external III-layer of IV-internal fusiform of I-Molecular pyramid granular layer pyramidal ells granular layer polymorphic layer cell layer cells • The incoming sensory signal excites neuronal layer IV first; then the signal spreads toward the surface of the cortex and also toward deeper layers. • Layers I and II & III perform most of intracortical association function. • The neurons in layers II and III making short horizontal connections with adjacent cortical areas. • The neurons in layers V and VI send output signals to brain stem ,spinal cord (V) & thalamus (VI) 9 ONLY IN MALES’ SLIDES There are three type of functional area of cerebral cortex primary motor& Secondary areas Association area sensory areas • primary motor areas • The secondary areas • They receive and analyze have direct make sense out of signals simultaneously connections with the signals from multiple regions of specific muscles for • in the primary areas. both the motor and causing discrete muscle sensory cortices as well movements. as from subcortical structures. • primary sensory • The most important areas detect specific association areas are: sensation(visual, • (1) Parieto- auditory,somatic) occipitotemporal transmitted directly to association area. the brain from • (2) prefrontal association peripheral sensory area. organs. • (3) limbic association area. 10 ONLY IN MALES’ SLIDES (1) Parieto-occipitotemporal association area Functions: • Analysis of the Spatial Coordinates of the Body. • Language Comprehension. • Initial Processing of Visual Language (Reading). • Area for Naming Objects. Area Site Function Beginning in the posterior Computes the coordinates of Analysis of the spatial coordinates parietal cortex and extending the visual , auditory, and body of the body. into the superior occipital surroundings. cortex Wernicke's area, lies behind the Higher intellectual Area for language primary auditory cortex in the function comprehension posterior part of the superior gyrus of the temporal lobe Make meaning out of the Area for initial processing of Angular gyrus area visually perceived words (lesion visual language (reading). causes dyslexia or word blindess) Area for naming Lateral portion of anterior occipital Naming objects. objects. lobe & posterior temporal lobe 11 ONLY IN MALES’ SLIDES Area of faces Prefrontal area limbic area recognition Is the anterior pole of frontal lobe. It contributes 1. Consists of anterior 1. Located on the underside of the brain on in the following functions: and inner portion of the medial occipital and temporal lobes. 1. Planning of complex pattern of movements. temporal lobe. 2. The occipital portion is contiguous with 2. Production of deep, more abstract and visual cortex , while the temporal one is logically sequenced thoughts which enable 2. It is primarily concerned with attainment of goals. emotion, behavior and closely associated with limbic system. 3. Working memory (ability to tie thoughts motivational drive for different 3. inability to recognize faces is called together in a logical sequence by comparing tasks most importantly learning. “prosopagnosia”. many bits of information with appropriate stored knowledge and be able to instantly 3. Lesion of this area may lead to recall this information for future planning). decreased aggression , lack of & emotion , hyper sexuality المنطقة هذي مسؤولة عن التفك ري المعقدر وإنشاء خطط وتنبؤات رف المخ وإذار مار كانت سليمة قدر يفقدر المريض الوظيفة hyperphagia هذه Lesions in this area lead to change in personality and behaviour 12 Four lobes of the brain Frontal Partial Temporal Occipital * Note: Occasionally, the Insula is considered the fifth lobe. It is located deep to the Temporal Lobe. 13 Frontal lobe 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: 1. Memory Formation 2. Emotions 3. Decision Making 4. Reasoning The frontal lobe is Responsible for initiation and execution of voluntary 5. Personality movement . • Also contains Broca’s area of speech in the dominnat hemisphere ( i.e., in the left hemisphere in most people ) . • Lesion can cause: 1. paralysis on opposite side of the body. 2. Aphasia: ( loss of ability to speak ) if lesion involves Broca’s area in the dominant hemispare. 14 Frontal lobe (cortical region) 3-Orbitofrontal cortex : 1. Primary motor cortex Site of frontal lobotomies. (precentral gyrus ): is a neurosurgical operation that involves severing connections in Cortical site involved with the brain's prefrontal lobe. controlling body movement Possible Side Effects: A. Epilepsy 2-Brocus area : B. Poor Emotional Responses plan of motor pattern for C. Perseveration (Uncontrolled, expressing of individual words, repetitive actions, gestures, or located on left frontal lobe (males) words) Controls facial neurons, speech, Desired Effects: and language A. Diminished Rage comprehension.(female) B. Decreased Aggression Located on Left Frontal Lobe. C. Poor Emotional responses “Broca’s Aphasia “: Results in the ability to comprehend 4-Olfactory Bulb : speech, but the decreased Cranial Nerve I, Responsible motor ability (or inability) to for sensation of Smell speak and form words. 15 Partial lobe The Parietal Lobe of the brain is located deep to the Parietal Bone of the skull. Parietal lobe is essential for our feeling of touch, warmth/heat, cold, pain, body position and appreciation of shapes of palpated objects. When damaged, the person loses the ability to recognize shapes of complex objects by palpation (palpation = examination of objects by touch) & develops Sensory Inattention on opposite side. It plays a major role in the following functions/actions: ONLY IN FEMALES’ SLIDES Partial lobe Contains
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