Brain & Cranial Nerves
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Transcript of Brain & Cranial Nerves
Brain & Cranial Nerves
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)
6 Major Regions of the Brain
Cerebrum Cerebellum Diencephalon Mesencephalon Pons Medulla oblongata
The Brain
Cerebrum Largest part of brain Controls higher mental functions Divided into left and right cerebral
hemispheres Surface layer of gray matter
(neural cortex)
Cerebral Cortex
3 Functional Principles of the Cerebrum
1. Each cerebral hemisphere receives sensory information from, and sends motor commands to, the opposite side of body
3 Functional Principles of the Cerebrum
2. The 2 hemispheres have different functions although their structures are alike
3 Functional Principles of the Cerebrum
3. Correspondence between a specific function and a specific region of cerebral cortex is not precise
Motor & Sensory Areas of the Cerebral
CortexWhere are the motor,
sensory, and association
areas of the cerebral cortex, and what are their functions?
Central sulcus separates motor and sensory areas
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
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
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
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
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)
Hemispheric Lateralization
Functional differences between left and right hemispheres
Each cerebral hemisphere performs certain functions not performed by the opposite hemisphere
The Left Hemisphere In most people, left brain
(dominant hemisphere) controls: reading, writing, and math decision-making speech and language
The Right Hemisphere Right cerebral hemisphere
relates to: senses (touch, smell, sight,
taste, feel) recognition (faces, voice
inflections)
Cerebellum Second largest part of brain Coordinates repetitive body
movements 2 hemispheres Covered with cerebellar cortex
The Cerebellum An autonomic processing center
Functions of the Cerebellum
1. Adjusts postural muscles 2. Fine-tunes conscious and
subconscious movements
Structures of the Cerebellum
Structures of the Cerebellum
Folia: surface of cerebellum highly folded neural cortex
Anterior and posterior lobes: separated by primary fissure
Structures of the Cerebellum
Cerebellar hemispheres: separated at midline by
vermis Vermis:
narrow band of cortex Flocculonodular lobe:
below fourth ventricle
Purkinje Cells Large, branched cells Found in cerebellar cortex Receive input from up to
200,000 synapses
Arbor vitae Highly branched, internal white
matter of cerebellum Cerebellar nuclei:
embedded in arbor vitae relay information to Purkinje
cells
The Peduncles Tracts link cerebellum with
brain stem, cerebrum, and spinal cord: superior cerebellar peduncles middle cerebellar peduncles inferior cerebellar peduncles