Brain & Cranial Nerves
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Transcript of Brain & Cranial Nerves
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Brain & Cranial Nerves
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The BrainRanges from 750 cc to 2100 cc
Contains almost 98% of the body’s neural tissue
Average weight about 1.4 kg (3 lb)
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6 Major Regions of the Brain
Cerebrum Cerebellum Diencephalon Mesencephalon Pons Medulla oblongata
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The Brain
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Cerebrum Largest part of brain Controls higher mental functions Divided into left and right cerebral
hemispheres Surface layer of gray matter
(neural cortex)
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Cerebral Cortex
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3 Functional Principles of the Cerebrum
1. Each cerebral hemisphere receives sensory information from, and sends motor commands to, the opposite side of body
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3 Functional Principles of the Cerebrum
2. The 2 hemispheres have different functions although their structures are alike
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3 Functional Principles of the Cerebrum
3. Correspondence between a specific function and a specific region of cerebral cortex is not precise
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Motor & Sensory Areas of the Cerebral
CortexWhere are the motor,
sensory, and association
areas of the cerebral cortex, and what are their functions?
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Central sulcus separates motor and sensory areas
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Motor Areas Precentral gyrus of frontal lobe:
directs voluntary movements Primary motor cortex:
is the surface of precentral gyrus Pyramidal cells:
are neurons of primary motor cortex
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Sensory Area Postcentral gyrus of parietal lobe:
receives somatic sensory information (touch, pressure, pain, vibration, taste, and temperature)
Primary sensory cortex: surface of postcentral gyrus
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Special Sensory Cortexes
Visual cortex: information from sight receptors
Auditory cortex: information from sound receptors
Olfactory cortex: information from odor receptors
Gustatory cortex: information from taste receptors
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Sensory Association Areas
Somatic sensory association area: interprets input to primary sensory
cortex (e.g., recognizes and responds to touch)
Visual association area: interprets activity in visual cortex
Auditory association area: monitors auditory cortex
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Other Integrative Areas
Speech center: is associated with general
interpretive area coordinates all vocalization
functions Prefrontal cortex of frontal lobe:
integrates information from sensory association areas
performs abstract intellectual activities (e.g., predicting consequences of actions)
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Hemispheric Lateralization
Functional differences between left and right hemispheres
Each cerebral hemisphere performs certain functions not performed by the opposite hemisphere
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The Left Hemisphere In most people, left brain
(dominant hemisphere) controls: reading, writing, and math decision-making speech and language
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The Right Hemisphere Right cerebral hemisphere
relates to: senses (touch, smell, sight,
taste, feel) recognition (faces, voice
inflections)
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Cerebellum Second largest part of brain Coordinates repetitive body
movements 2 hemispheres Covered with cerebellar cortex
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The Cerebellum An autonomic processing center
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Functions of the Cerebellum
1. Adjusts postural muscles 2. Fine-tunes conscious and
subconscious movements
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Structures of the Cerebellum
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Structures of the Cerebellum
Folia: surface of cerebellum highly folded neural cortex
Anterior and posterior lobes: separated by primary fissure
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Structures of the Cerebellum
Cerebellar hemispheres: separated at midline by
vermis Vermis:
narrow band of cortex Flocculonodular lobe:
below fourth ventricle
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Purkinje Cells Large, branched cells Found in cerebellar cortex Receive input from up to
200,000 synapses
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Arbor vitae Highly branched, internal white
matter of cerebellum Cerebellar nuclei:
embedded in arbor vitae relay information to Purkinje
cells
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The Peduncles Tracts link cerebellum with
brain stem, cerebrum, and spinal cord: superior cerebellar peduncles middle cerebellar peduncles inferior cerebellar peduncles
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