Download to read offline
frontal_lobe_batch2.pptxbbnnmmdmssmmsmssssk
- 1. Frontal Lobe –Physiology, Blood Supply & Functions Batch 2 of 3 Based on Bradley’s Neurology (8th), DeJong’s (8th), Bickerstaff’s
- 2. Physiology of theFrontal Lobe • Integration of motor, cognitive, and behavioral processes • Primary motor cortex: execution of movement • Premotor and SMA: motor planning, coordination • Prefrontal cortex: executive functions, decision-making • Orbitofrontal: social and emotional regulation
- 3. Motor Physiology –Primary Motor Cortex • Direct corticospinal and corticobulbar outputs • Somatotopic representation (motor homunculus) • Fine control of distal limb movements • Neurons fire in anticipation of movement
- 4. Premotor Cortex &SMA • Premotor cortex: selection of movements in response to external cues • SMA: internally generated movement planning • Bimanual coordination • Lesions → apraxia, impaired sequence initiation
- 5. Frontal Eye Fields(Area 8) • Control of voluntary saccadic eye movements • Contralateral gaze control • Lesion → transient gaze deviation toward lesion • Electrical stimulation → contralateral saccades
- 6. Prefrontal Physiology • Dorsolateral:working memory, planning, problem solving • Orbitofrontal: inhibition, emotional control, social judgment • Medial: motivation, attention, initiation of action • Reciprocal connections with limbic, parietal, and temporal regions
- 7. Neurotransmitters in Frontal Function •Dopamine – mesocortical pathway, critical for working memory and flexibility • Serotonin – mood regulation, impulse control • Norepinephrine – attention, arousal • Acetylcholine – modulation of cortical excitability
- 8. Blood Supply ofthe Frontal Lobe • Anterior cerebral artery (ACA) – medial frontal lobe, paracentral lobule • Middle cerebral artery (MCA) – lateral convexity • ACA–MCA watershed zone – proximal arm/leg representation • Orbitofrontal branches from both ACA and MCA
- 9. ACA Territory • Suppliesmedial surface (paracentral lobule, SMA) • Lesion → contralateral leg weakness > arm • Also supplies medial prefrontal regions • Affects motivation, attention, personality
- 10. MCA Territory • Supplieslateral convexity (face, arm motor cortex) • Broca’s area and dorsolateral prefrontal cortex • Lesion → contralateral face-arm weakness, aphasia (dominant hemisphere) • Also affects executive function and attention
- 11. Venous Drainage ofFrontal Lobe • Superficial veins drain into superior sagittal sinus • Deep veins drain into internal cerebral vein • Clinical relevance: venous infarcts less common but severe • Important in trauma and raised intracranial pressure
- 12. Functional Areas ofthe Frontal Lobe • Primary motor cortex – movement execution • Premotor and SMA – movement planning • Broca’s area – speech production • Prefrontal cortex – executive control • Orbitofrontal cortex – behavior regulation • Medial frontal cortex – motivation, attention
- 13. Dorsolateral Prefrontal Cortex •Executive functions: planning, reasoning, problem solving • Working memory • Cognitive flexibility • Lesion → poor planning, perseveration, disorganization
- 14. Orbitofrontal Cortex • Regulationof behavior, impulse control • Reward processing • Social appropriateness • Lesion → disinhibition, socially inappropriate behavior
- 15. Medial Frontal Cortex •Drive, motivation, initiation • Attention control • Lesion → apathy, akinetic mutism • Connections with cingulate and limbic system
- 16. Broca’s Area (Areas44, 45) • Language production, articulation planning • Located in dominant hemisphere inferior frontal gyrus • Lesion → Broca’s aphasia (non-fluent, effortful speech) • Preserved comprehension