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Motor Areas
anterior part of each hemisphere
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primary motor area
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controls voluntary contraction of specific muscles or
groups of muscles
more area for muscles of skilled, complex, or delicate
movement
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Broca’s speech area
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left frontal lobe for 97% of population
planning and production of speech
from Broca’s to
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premotor area to motors of
larynx, pharynx, mouth
primary motor area to control
breathing muscles
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Figure 15.5b
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Association Areas
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often adjacent to primary sensory areas
usually receive input from both primary
sensory areas and other brain regions
integrate sensory experiences to generate
meaningful patterns of recognition and
awareness
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damage to primary visual area of brain
results in loss of vision
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damage to visual association area would not
recognize what they are seeing
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Association Areas
somatosensory association area
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integrates and interprets sensations
determines shape and texture of object without looking at
it
determines orientation of one object with respect to
another as they are felt
sense relationship of one body part to another
storage of memories of past experiences to compare
current sensations with previous experiences
visual association area
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receives sensory impulses from primary visual area and
thalamus
relates present and past visual experiences
essential in recognizing and evaluating what is seen
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Association Areas
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auditory association area
allows recognition of sound as speech, music, or noise
Wernicke’s area
broad region in left temporal and parietal lobes
interprets meaning of speech by recognizing spoken
words
translates words into thoughts
right hemisphere correspond to Broca’s and Wernicke’s
in the left
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contribute to verbal communication by adding
emotional content like anger, joy, or spoken words
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Association Areas
common integrative area
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integrates sensory interpretations from all sensory
association areas
allowing formation of thoughts based on variety of
sensory inputs
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transmits signals to other parts of brain to cause
appropriate response
premotor area
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immediately anterior to primary motor area
controls learned, skilled, motor activities of a complex
and sequential nature
causes specific groups of muscles to contract in specific
sequence
serves as memory bank for specific patterns of
movements
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Association Areas
frontal eye field area
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controls voluntary scanning movements of eye
reading for example
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Hemispheric Lateralization
functional asymmetry
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each hemisphere also specializes in performing
certain unique functions
appears at about 30 weeks in fetal
development
left hemisphere receives somatic sensory
signals from controls muscles on the right side
of the body
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right hemisphere receives and controls the left
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Hemispheric Lateralization
left hemisphere
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reasoning, numerical and scientific skills
spoken and written language
ability to use and understand sign language
right hemisphere
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musical and artistic awareness
spatial and pattern perception
recognition of faces
emotional content of language
discrimination of different smells
generating mental images of sight, sound, touch,
taste, and smell to compare relationships among
them
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Figure 13.11
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Table 13.1
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Concept 13.6
Diencephalon
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Diencephalon
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extends from brain stem to cerebrum
surrounds third ventricle
thalamus
hypothalamus
pineal gland
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Thalamus
3cm in length
80% of diencephalon
paired oval masses of gray matter
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intermediate mass
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organized into nuclei
interspersed tracts of white matter
crosses third ventricle
joins left and right halves of thalamus
relays and processes sensory and motor
information
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Thalamus
with other parts of the brain helps regulate
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autonomic activities
emotions
maintains consciousness
pain perception
learning
memory
cognition (thinking and knowing)
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Figure 13.1a
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Figure 13.1c
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Figure 13.9a
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Figure 13.12
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Hypothalamus
small part of diencephalon inferior to thalamus
12 or so nuclei
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mammillary bodies
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serve as relay stations for reflexes to sense of smell
infundibulum
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connects pituitary gland
major regulator of homeostasis
continually monitors conditions within blood
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osmotic pressure, glucose levels, hormone
concentrations, temperature
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Important Functions of Hypothalamus
Control of ANS
1.
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regulator of visceral activities including heart rate,
movement of food through GI tract, contraction of
urinary bladder
Production of hormones
2.
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through bloodstream and axons to pituitary
Regulation of emotional and behavioral
patterns
3.
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works with limbic system
Regulation of eating and drinking
4.
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insulin passes BBB stimulating or inhibiting food
intake
thirst center sensitive to osmotic pressure
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Important Functions of Hypothalamus
Control of body temperature
5.
•
stimulates body to promote heat loss if too hot and
heat production and retention if too cold
Regulation of circadian rhythms and states of
consciousness
6.
•
sleep and wake cycles
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Figure 13.13ab
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Figure 13.13c
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Pineal Gland
size of a small pea
considered part of endocrine system
secretes melatonin
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promotes sleepiness
contributes to setting of body’s biological clock
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Concept 13.7
Brain Stem
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Brain Stem
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between spinal cord and diencephalon
three regions
1.
midbrain
2.
pons
3.
medulla oblongata
contain both tracts and nuclei
act as relay centers for processing and controlling
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involuntary of sight and sound processing
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eye movement
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regulation of autonomic functions
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respiration, heart rate, blood pressure, digestion
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Midbrain
conducts nerve impulses from cerebrum to spinal
cord, medulla, and pons
peduncles have axons of sensory neurons
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medulla to thalamus
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regions
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corpora quadrigemina
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superior colliculi
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reflex centers for some visual activities
inferior colliculi
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reflex centers for some reactions to auditory
stimuli
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Pons
anterior to cerebellum
inferior to midbrain
2.5cm long
tracts that connect parts of brain
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e.g. left and right cerebellum
voluntary movements relayed from cerebral
cortex to cerebellum
help control breathing
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pneumotaxic area
apneustic area
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Figure 13.1a
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Figure 13.1c
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Figure 13.14
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Figure 13.15
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Medulla Oblongata
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inferior part of brain stem
continuation of spinal cord
3cm from pons to foramen magnum
all sensory and motor tracts connecting brain
and spinal cord
pyramids
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white matter bulges
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largest motor tracts
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90% of left pass to right & right to left
cardiovascular and medullary rhythmicity
areas
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Reticular Formation
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small clusters of neuronal cell bodies within
small bundles of myelinated axons
RAS
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sensory axons that project cerebral cortex
helps maintain consciousness
active during awakening from sleep
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RAS arouses cerebral cortex
motor tracts
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help regulate muscle tone
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Concept 13.8
Cerebellum
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Functions of Cerebellum
anterior and posterior lobes govern subconscious
aspects of skeletal muscle movements
flocculondular lobe on inferior surface contributes to
equilibrium and balance
main function
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cerebellum evaluates movements
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smoothes movements
corrects errors
coordinates sequence
regulates posture and balance
makes possible all skilled muscular activities
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Table 13.2 part 3
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Concept 13.9
Spinal Cord
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External Spinal Cord Anatomy
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roughly circular but flattened slightly in anteriorposterior dimension
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~2cm diameter
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larger in cervical and lumbar enlargements
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smallest at inferior tip
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adult spinal cord length
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from 42 to 45 cm
from medulla oblongata to L2
filum terminale
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extension of pia mater
extends inferiorly
anchors spinal cord to coccyx
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Figure 13.2
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External Spinal Cord Anatomy
31 pair of spinal nerves
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exit vertebral column at intervertebral foramina
each pair called spinal segment
paths of communication
roots
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bundles of axons that connect peripheral
nerves and spinal cord
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posterior or dorsal root
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sensory neuron axons
anterior or ventral root
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motor neuron axons
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Figure 13.4b
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Internal Spinal Cord Anatomy
right and left sides
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anterior median fissure
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deep and wide groove
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posterior median sulcus
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shallower, narrower
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gray matter surrounded by white matter
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gray matter shaped like an “H” or a butterfly
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gray commissure
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crossbar of H connects gray matter L & R sides
central canal
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contiguous with 4th ventricle
white commissure
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anterior to gray
commissure connects white matter on L & R sides
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Internal Spinal Cord Anatomy
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gray matter
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cell bodies, neuroglia, unmyelinated axons of
sensor neurons, dendrites of interneurons, motor
neurons
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divided into horns
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anterior horn
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cell bodies of somatic motor neurons and
motor nuclei
posterior horn
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somatic and autonomic sensory nuclei
lateral gray horns
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absent in cervical segments
cell bodies of autonomic motor neurons
regulating smooth and cardiac muscle,
and glands
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Internal Spinal Cord Anatomy
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white matter
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bundles of myelinated and unmyelinated
axons of sensory neurons, interneurons,
and motor neurons
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divided into columns
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anterior, posterior, and lateral
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tracts having common origin or
destination and carrying similar
information over long distances
sensory tracts
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toward CNS
motor tracts
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away from CNS
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Concept 13.10
Spinal Cord Impulses
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Sensory Tracts
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spinothalamic tracts and posterior columns
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lateral and anterior spinothalamic tracts
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pain, warmth, coolness, itching, tickling, deep
pressure, crude poorly localized sense of touch
right and left posterior columns
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proprioception, discriminative touch, two point
discrimination, light pressure and vibration
sensations
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Figure 13.19a
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Figure 13.19b
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Motor Tracts
down spinal cord in two pathways
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direct pathways
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impulses destined to cause precise, voluntary
movements of skeletal muscles
indirect pathways
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govern automatic movements
help coordinate body movements with visual
stimuli
major role in equilibrium my maintaining skeletal
muscle tone and contraction of postural muscles
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Spinal Reflexes
spinal reflex
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integration occurs in spinal cord gray matter
cranial reflex
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integration that occurs in brain
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End Chapter 13
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