Download Brain and Spinal Cord

Chapter 11
Nervous System II
Meninges
• membranes
surrounding CNS
• protect CNS
• three layers
• dura mater – outer,
tough
• arachnoid mater weblike
• pia mater – inner,
delicate
11-2
Ventricles
• interconnected cavities
• within cerebral
hemispheres and brain
stem
• continuous with central
canal of spinal cord
• filled with cerebrospinal
fluid (csf)
• lateral ventricles
• third ventricle
• fourth ventricle
• cerebral aqueduct
11-4
Cerebrospinal Fluid
• secreted by choroid
plexus
• circulates in ventricles,
central canal of spinal
cord, and subarachnoid
space
• completely surrounds
brain and spinal cord
• clear liquid
• nutritive and protective
• helps maintain stable ion
concentrations in CNS
11-5
Spinal Cord Structure
• extends foramen magnum to 2nd lumbar vertebra
11-6
Cross Section of Spinal Cord
11-7
Spinal Cord Functions
• center for spinal reflexes
• conduit for nerve impulses to and
from the brain
11-8
Reflex Arcs
Reflexes – automatic, subconscious responses to stimuli
11-9
Tracts of the Spinal Cord
• Ascending tracts conduct sensory impulses to the brain
• Descending tracts conduct motor impulses from the brain to
motor neurons reaching muscles and glands
11-13
Brain
Functions
Major Parts
• interprets sensations
• cerebrum
• two cerebellar hemispheres
• determines perception
• diencephalon
• stores memory
• brain stem
• reasoning
• cerebellum
• makes decisions
• coordinates muscular
movements
• regulates visceral activities
• determines personality
11-16
Brain Development
Three Major Vesicles
1. Forebrain
2. Midbrain
3. Hindbrain
Forebrain (prosencephalon)
• anterior portion (telencephalon)
• cerebrum
• basal ganglia
• posterior portion (diencephalon)
• thalamus
• hypothalamus
• posterior pituitary
• pineal gland
11-17
Brain Development
Midbrain (mesencephalon)
• midbrain
Hindbrain (rhombencephalon)
• anterior portion (metencephalon)
• cerebellum
• pons
• posterior portion (myelencephalon)
• medulla oblongata
11-18
Structure of Cerebrum
• corpus callosum
• connects hemispheres
• convolutions
• bumps or gyri
• sulci
• grooves
• longitudinal fissure
• separates hemispheres
• transverse fissure
• separates cerebrum from
cerebellum
11-19
Lobes of Cerebrum
• Frontal
• Parietal
• Temporal
• Occipital
• Insula
11-20
Functions of Cerebrum
• interpretation
• initiating voluntary movements
• storing memory
• retrieving memory
• reasoning
• center for intelligence and personality
11-21
Functional Regions of
Cerebral Cortex
Cerebral Cortex – thin layer of gray matter that
constitutes the outermost portion of cerebrum; contains
75% of all neurons in nervous system
11-22
Motor Areas
• Primary Motor Areas
• frontal lobes
• control voluntary muscles
• Broca’s Area
• anterior to primary motor
cortex
• usually in one hemisphere
• controls muscles needed for
speech
• Frontal Eye Field
• above Broca’s area
• controls voluntary
movements of eyes and
eyelids
11-23
Motor Areas
11-24
Sensory Areas
• Cutaneous Sensory
Area
• parietal lobe
• interprets sensations
on skin
• Visual Area
• occipital lobe
• interprets vision
• Auditory Area
• temporal lobe
• interprets hearing
11-25
Sensory Areas
11-26
Association Areas
• regions of cortex that are not primary motor or primary
sensory areas
• widespread throughout the cerebral cortex
• analyze and interpret sensory experiences
• provide memory, reasoning, verbalization, judgment, emotions
11-27
Association Areas
Frontal Lobe Association Areas
• concentrating
• planning
• problem solving
• judging
Temporal Lobe Association Areas
• remember visual scenes
• remember music
• remember complex patterns
Parietal Lobe Association Areas
• understanding speech
• using words to express
thought
Occipital Lobe Association Areas
• combine visual images with
other sensory experiences
11-28
Hemisphere Dominance
• In over 90% of population, left hemisphere is dominant
• Dominant hemisphere
controls
• speech
• writing
• reading
• verbal skills
• analytical skills
• computational skills
• Nondominant hemisphere
controls
• nonverbal tasks
• motor tasks
• understanding and
interpreting musical and
visual patterns
• provides emotional and
intuitive thought processes
11-29
Memory
Short Term
• working memory
• closed circuit
• circuit is stimulated over
and over
• when impulse flow
stops, memory disappears
Long Term
• changes structure
and function of
neurons
• enhanced synaptic
transmission
11-30
Basal Nuclei
• masses of gray matter
• deep within cerebral
hemispheres
• caudate nucleus, putamen,
globus pallidus
• produce dopamine
• control certain muscular
activities
11-31
Diencephalon
• between cerebral hemispheres and brainstem
• surrounds third ventricle
• thalamus
• hypothalamus
• optic tracts
• optic chiasm
• infundibulum
• posterior pituitary
• mammillary bodies
• pineal gland
11-32
Brain Stem
Three Parts
1. Midbrain
2. Pons
3. Medulla Oblongata
11-35
Midbrain
•contains bundles of fibers
that join lower parts of
brainstem and spinal cord
with higher part of brain
11-36
Pons
• rounded bulge on underside of
brainstem
• between medulla oblongata
and midbrain
• helps regulate rate and depth
of breathing
• relays nerve impulses to and
from medulla oblongata and
cerebellum
11-37
Medulla Oblongata
• enlarged continuation of
spinal cord
• conducts ascending and
descending impulses between
brain and spinal cord
• contains cardiac, vasomotor,
and respiratory control
centers
• contains various nonvital
reflex control centers
(coughing, sneezing,
vomiting)
11-38