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Download CHAPTER 19 CENTRAL NERVOUS SYSTEM – BRAIN
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CHAPTER 12 CENTRAL NERVOUS SYSTEM – BRAIN Central Nervous system • • brain control center spinal cord superhighway Brain – developmental areas • • telencephalon cerebrum diencephalon thalamus hypothalamus epithalamus mesencephalon midbrain metencephalon pons cerebellum • myelencephalon medulla oblongata • brain stem midbrain pons medulla oblongata • • = Cerebrum • R and L cerebral hemispheres • gray matter • • • cell bodies and interneurons outer gray matter = cortex inner gray matter white matter myelinated axons bumps and grooves • • • • • • • • • • gyrus bumps sulcus grooves fissure deep sulcus longitudinal fissure separate hemispheres transverse cerebral fissure separates cerebrum from cerebellum lateral sulcus betw parieto-occipital sulcus central sulcus precentral gyrus postcentral gyrus CNS – dorsal / ventral • • dorsal sensory ventral motor Lobes of Cerebrum • • • • • frontal lobe parietal lobe temporal lobe occipital lobe insula internal at lateral sulcus cortex functional areas • • motor – – – conscious motor frontal - precentral gyrus eye movement frontal speech movement frontal (Broca’s area) sensory – – – – – – conscious sensation parietal – postcentral gyrus auditory temporal olfactory temporal , limbic system visual occipital taste parietal equilibrium insula ? frontal lobe • • • primary motor cortex – – conscious motor precentral gyrus pyramidal cells pyramidal (corticospinal) tract frontal eye field Broca’s area frontal lobe • • premotor cortex complex, learned movements prefrontal cortex social skills emotion parietal lobe • • • primary somatosensory cortex – post-central gyrus taste (gustatory) Wernicke’s area understanding spoken words also in temporal lobe occipital lobe • • primary visual cortex largest sensory area (humans) visual association area analyzing visual information memory of “ temporal lobe • primary auditory cortex • Wernicke’s area understanding spoken words white matter • commissural fibers – corpus callosum • association fibers • projection fibers – – internal capsule corona radiata areas on same hemisphere internal gray matter • • • • Basal ganglia Thalamus Hypothalamus epithalamus basal ganglia = basal nuclei • lentiform nuclei – – globus pallidus putamen • caudate nucleus • functions : start and stop movements intensity of movement works with Substantia Nigra Thalamus • • • “gateway to the cerebrum” sensory relay – all sensory info to cortex goes through thalamus sensory filter weak, unimportant stimuli Hypothalamus • visceral control center – – – – – – – regulates organ functions temperature hunger glucose, amino acids thirst salts, water Autonomic NS emotions visceral responses endocrine controls Pituitary gland sleep-wake cycles input from optic nerve epithalamus • • • pineal gland secretes melatonin stimulates sleep cycle control from hypothalamus brain stem • • • • 3 parts : – – – midbrain pons medulla oblongata vital functions passageway betw cortex and spinal cord cranial nerves midbrain • • • • cranial nerves nuclei III , IV corpora quadrigemina – – superior colliculi visual reflexes inferior colliculi auditory reflexes cerebral peduncles pyramidal motor tracts superior cerebellar peduncles cerebellum to midbrain • substantia nigra influences basal ganglia produces Dopamine • red nucleus flexion movements muscle tone pons • • • cranial nerves nuclei V , VI , VII middle cerebellar peduncles – axons from pons to cerebellum respiratory centers medulla oblongata • • cranial nerve nuclei VIII, IX, X, XI, XII visceral motor nuclei cardiac center vasomotor center respiratory center • inferior cerebellar peduncles • pyramids HR BP resp rate medulla to cerebellum pyramidal tracts medulla oblongata – relay functions • • • • • • vestibular nuclei equilibrium relay cochlear nuclei auditory relay olivary nuclei proprioception relay nucleus gracilis ; cuneatus touch, pressure relay solitary nucleus taste reflexes swallow cough sneeze BP , HR , Resp cerebellum • • • • • coordination of voluntary movements cerebellar hemispheres vermis connects hemispheres arbor vitae white matter (inner) cerebellar peduncles connect to brain stem – – – superior midbrain to cerebrum middle pons from cerebrum inferior medulla from body limbic system • • • emotional brain – – amygdala fear, anger cingulate gyrus emotions, gestures memory / learning – – – hippocampus short term memory amygdala memories of emotions hypothalamus visceral responses fornix connects 2 limbus reticular formation • • • • center of brain stem reticular activating system (RAS) – maintains consciousness and alertness input from all senses motor to all muscles meninges • • • • cover and protect CNS Dura mater – – – periosteal layer lines skull meningeal layer protects ; limits movement • falx cerebri longitudinal fissure secured to crista galli • tentorium cerebelli dural sinuses Arachnoid – – outer drains excess CSF middle subarachnoid space contains CSF arachnoid villi Pia mater project into dural sinuses inner covers CNS surface cerebrospinal fluid • • • liquid cushion nourish brain and remove wastes choroid plexus produces CSF from plasma ependymal cells of ventricles • flows through ventricles subarachnoid space central canal of spinal cord • drains into dural sinuses then into veins ventricles • • • • brain’s central cavity lateral ventricles – septum pellucidum third ventricle – cerebral aqueduct fourth ventricle – – apertures central canal in cerebral hemispheres median membrane in diencephalon connects 3rd and 4th dorsal to pons connect to subarachnoid space continues in spinal cord
