CEREBRUM - FUNCTIONAL AREAS

Functional areas of Cerebrum: A presentation for Medical Students

1. CEREBRUM FUNCTIONAL AREAS DR SURAJIT KUNDU DEPARTMENT OF ANATOMY GOVERNMENT MEDICAL RAIGARH (CG)

2. CLINICAL QUESTION An adult male person with road accident was brought to the emergency of hospital. He was clinically examined with following symptoms: No bleeding areas seen but some bruises No loss of consciousness No loss of muscle tone or weakness Patient responded to all general sensations Special sensation of vision and audition were within limits The patient could not speak but was able to write his name and contact number 1. Name the area of brain which might be involved due the accident 2. Identify the symptom in (f) above 3. Locate area of the skull which might have received the thrust of accident 4. Correlate clinically

3. CLINICAL QUESTION

4. CLINICAL QUESTION a. Recalling your knowledge, correlate the abnormality presented and identify the area of brain which might be possibly involved b. Mention the functional area involved

5. Objectives ( At the end of the session you should be able to ……………… ) To define functional areas of Cerebrum Classify Functional areas Identify primary function of each lobe Understand the word “Motor Homunculus” Draw a well labeled diagram representing the Functional areas Understand the location, functions and related clinical correlation of each Functional area

6. DEFINITION AREAS PRESENT WITHIN THE SPECIFIED SULCI & GYRI OF CEREBRUM WHICH CONTROLS SPECIFIC MOTOR OR SENSORY FUNCTIONS OF CEREBRAL CORTEX INCLUDING HIGHER INTELLECTUAL ACTIVITIES

7. CLASSIFICATION CLASSIFIED BY GERMAN NEUROLOGIST K BROADMANN (1909) INTO: Motor areas Sensory areas Association areas (Each With unique Broadmann’s number) Each lobe of cerebrum has specific functions (Sensory Area)

8. CLASSIFICATION & NAMES NAME OF CEREBRAL LOBE FUNCTIONAL AREA FRONTAL LOBE 1. Primary motor area (area 4) 2. Pre motor area (area 6 ) 3. Frontal eye field (Area 8) 4. Motor speech area of Broca (area 44 and 45) 5. Prefrontal area (area 9, 10, 11, 12) TEMPORAL LOBE 1. Primary sensory area (Area 3,1, and 2) 2. Sensory association area (Area 5 and 7) 3. Sensory speech area of Wernicke (Area 39 and 40) PARIETAL LOBE 1. Primary auditory area (Area 41 and 42) 2. Secondary auditory area / Auditory association area (Area 22) OCCIPITAL LOBE 1. Primary visual area/ striate area (Area 17) 2. Secondary visual area/ Visual association area (Area 18 & 19)

9. LOBES AND PRIMARY FUNCTIONAL AREAS

10. FUNCTIONS, LOCATION & APPLIED ANATOMY OF INDIVIDUAL FUNCTION AREAS (OF EACH LOBE)

11. FRONTAL LOBE NAME & NUMBER LOCATION FUNCTION APPLIED ANATOMY Primary motor area (Area no. 4) Contain giant Pyramidal Betz cells giving rise to 40% Pyramidal tract fibres) Has inverted Homunculus Pre central gyrus (superolateral surface) & part of para central lobule (medial surface) Control voluntary motor activity - opposite side of body Contra lateral Hemiplegia except masticatory muscles , laryngeal, pharyngeal , upper facial and extra ocular muscles 2. Pre motor area (Area no 6) (Anterior to primary motor area) Posterior part of superior , middle and inferior frontal gyrus Main site for cortical origin of extra pyramidal tracts controlling s uccessful performance of skilled voluntary motor activities Difficulty in the performance of skilled movements (Dyspraxia) 3. Frontal eye field (Area 8) Posterior part of middle frontal gyrus (Just anterior pre central gyrus) Controls conjugate coordinate movements of the eyes to opposite side without visual stimulus Loss of its function described 4. Broca’s Motor speech area (Area 44 and 45) Pars Triangularis and Pars Opercularis of inferior frontal gyrus Production of expressive speech/vocalization/ Motor speech (No loss of Stimulation of the muscles of the larynx, mouth, tongue, soft palate, and the respiratory muscles) Motor aphasia (Language is understood but cannot be expressed as speech) 5. Prefrontal area (Frontal Association Area) (Are no. 20) Frontal pole Controls personality, judgment, emotion, thinking, concentration, will power, orientation Loss of functions described

12. INVERTED HOMUNCULUS (Inverted representation of human body) Primary motor area represents Inverted Homunculus (Human body is represented upside down at pre - central Gyrus ) Only movements are represented, not muscles Pharyngeal region & tongue – Lowermost part Followed by face, hand, trunk & thigh Legs, feet & perineum are represented on the medial surface (Para central lobule) Face & hand have proportionately large areas but trunk & lower limb have smaller areas

13. PARIETAL LOBE NAME & NUMBER LOCATION FUNCTION APPLIED ANATOMY Primary sensory area (Area 3,1, and 2) Granular cortex packed with satellite cells with scanty number of small and medium sized pyramidal cells Has inverted Homunculus Post central gyrus & posterior part of the para central lobule on the medial surfce Reception & perception of Extero-ceptive (pain, touch and temperature) Proprioceptive (vibration, muscle, and joint sense) sensations from the opposite half of the body thorough fibres from ventral posterolateral (VPL) and ventral posteromedial (VPM) nuclei of the thalamus Loss of sensation from opposite side (Contra lateral) of body 2. Sensory association area (Area 5 and 7) Superior parietal lobule Reception & perception of shape, size, roughness, and texture of the objects & Stereo gnosis Tactile Agnosia & Astereognosis 3. Sensory speech area of Wernicke (Area 39 and 40) (Wernicke’s area is connected with Broca’s area by a bundle of nerve fibres called as Arcuate Fasciculus) Posterior part of the superior temporal gyrus of temporal lobe and angular gyrus & Supra marginal gyrus of the inferior parietal lobule Interpretation of language through visual and auditory input Sensory aphasia (Individual has fluent speech but unaware of the incorrect or non existent words used – Incomprehensive foreign language)

14. TEMPORAL LOBE NAME & NUMBER LOCATION FUNCTION APPLIED ANATOMY Primary auditory area (Area 41 and 42) (Receives afferents from Medial Geniculate body) Superior surface of superior temporal gyrus ( Heschl’s gyrus) Reception & perception of loudness, quality, pitch, direction & source of sound waves Slight loss of hearing as it receives auditory input from the cochleae of both ears, but l oss will be greater in the opposite ear 2. Secondary auditory area / Auditory association area (Area 22) Lateral surface of the superior temporal gyrus slightly posterior to the primary auditory area Receives auditory impulses (loudness, quality, pitch, direction & source of sound waves) from primary auditory area and correlates them with the past auditory experiences Auditory verbal Agnosia (I nability to interpret the meaning of the sounds heard)

15. OCCIPITAL LOBE NAME & NUMBER LOCATION FUNCTION APPLIED ANATOMY Primary visual area/ striate area (Area 17) (Receives afferents from Lateral Geniculate body) Posterior part of the calcarine sulcus ( Post Calcarine sulcus) and occipital pole Reception and perception of visual impulses like colour, size, form, motion, illumination and transparency of light waves Crossed homonymous Hemianopia (loss of vision in the opposite visual field) or Superior quadrantic hemianopia or inferior quadrantic hemianopia (Loss of vision of upper or lower quadrant of eye) 2. Secondary visual area/ Visual association area (Area 18 & 19) Surrounds the primary visual area & remaining visual cortex on the medial and supero - lateral surfaces Receives a fferent s from primary visual area & correlates the information with past visual experiences, thus enabling the individual to recognize and appreciate what he is seeing Visual Agnosia (Anton Syndrome) The patient acts as though he can see, and when attempting to walk, collides with objects

16. OTHER FUNCTIONAL AREAS NAME OF FUNCTIONAL AREA LOCATION Taste area (gustatory area (Area 43) Inferior part of the parietal lobe, posterior to the general sensory area ( lower end of the post central gyrus or in the adjoining area of the insula) 2. Olfactory area (Area 28) Parahippocampal gyrus and uncus

17. QUESTIONS Functional areas of Cerebrum (Short note) Draw a well labeled diagram of superolateral surface of Cerebrum representing the functional areas (Short note)

18. CLINICAL QUESTION Are you able to answer and correlate the clinical questions asked at the beginning of the session ???????????

19. THANK YOU (FOR LENDING ME ALL YOUR FUNCTIONAL AREAS) For the last ……………….. hour 26