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Brain stem- continuationof the spinal cord;
consists of the medulla oblongata, pons and
midbrain.
Cerebellum- second largest part of the brain.
Diencephalon- gives rise to thalamus,
hypothalamus and epithalamus.
Cerebrum- largest part of the brain.
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The cranium
The cranial meninges: dura mater, arachnoid
mater and pia mater.
Three extensions of the dura mater separate
parts of the brain:
a. Falx cerebri separate the two cerebral
hemispheres.
b. Falx cerebelli separate the two cerebellar
hemispheres.
c. Tentorium cerebelli separate the cerebrum
from the cerebellum.
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Brain receives approximately 20% of the total
blood supply.
Internal carotid and vertebral arteries carry
blood to the brain.
Internal jugular veins return blood from the
brain.
Blood-brain barrier (BBB) protects brain from
harmful substances.
Clear fluid.
Circulates through cavities in the brain
(ventricles) and the spinal cord (central canal)
and also in the subarachnoid space.
Absorbs shock and protects the brain and the
spinal cord.
Helps transport nutrients and wastes from
the blood and the nervous tissue.
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CSF-filled cavities within the brain.
Lateral ventricles: cerebral hemispheres.
Third ventricle: diencephalon.
Cerebral aqueduct: midbrain.
Fourth ventricle: brain stem and the cerebellum.
Choroid plexuses- networks of capillaries in the walls of the
ventricles.
Ventricles are lined by ependymal cells.
Plasma is drawn from the choroid plexuses through
ependymal cells into the ventricles to produce CSF.
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CSF from the lateral
ventricles →
interventricular
foramina → third
ventricle → cerebral
aqueduct → fourth
ventricle →
subarachnoid space or
central canal.
CSF is reabsorbed into
the blood by arachnoid
villi.
Pyramids-
Bulges on the
anterior aspect
of the medulla.
Formed by the
large
corticospinal
tracts that pass
from the
cerebrum to the
spinal cord.
A common site
for decussation
of ascending and
descending
tracts.
Vital centers:
Cardiovascular center-
Respiratory center-
Also includes centers for vomiting,
swallowing, sneezing, coughing and
hiccupping.
Houses five pairs of cranial nerves,VIII-XII.
Portion of the ventricle found here is the
fourth ventricle.
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Extends from the pons to the diencephalon.
Part of the ventricle found here- cerebral aqueduct.
Cerebral peduncles: axons of the corticospinal,
corticopontine and corticobulbar tracts.
Tectum- situated posteriorly and contains four
rounded elevations: two superior ones called
superior colliculi and two inferior ones called inferior
colliculi.
Substantia nigra: large area with dark
pigments. Help control subconscious muscle
activities. Loss of neurons here is associated
with Parkinson disease.
Red nucleus: Help control voluntary
movements of the limbs.
Contains cranial nerves III-IV.
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Extends from the upper part of the spinal
cord, throughout the brain stem, and into the
lower part of the diencephalon.
Part of the reticular formation called the
reticular activating system (RAS) consists of
sensory axons that project to the cerebral
cortex.
The RAS helps maintain consciousness.
Second largest part of the brain.
The central constricted area is the vermis.
The anterior and posterior lobes control
subconscious aspects of skeletal movement.
The flocculonodular lobe on the inferior side
contributes to the equilibrium and balance.
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Cerebellar cortex- gray matter in the form of
parallel folds called folia.
Arbor vitae- tracts of white matter.
Cerebellar peduncles- three pairs: superior,
middle and inferior.Attach cerebellum to the
brain stem.
Functions- coordinate movements, regulate
posture and balance.
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Intermediate mass
Several nuclei:
Major relay station for
most sensory
impulses.
Inferior to the thalamus.
Consists of mammillary body, median eminence,
infundibulum, and a number of nuclei.
Control of theANS.
Production of hormones
Regulation of emotional and behavioral
patterns, eating and drinking, body
temperature, and circadian rhythms.
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Small region superior to the thalamus.
Consists of pineal gland which secretes a
hormone called melatonin.
Melatonin induces sleep.
“seat of intelligence”
Cerebral cortex- gray matter.
Gyri-
Sulci-
Longitudinal fissure-
Cerebral hemispheres-
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Four lobes: frontal lobe, parietal lobe,
temporal lobe and occipital lobe.
Central sulcus- separates the frontal and
parietal lobes.
Precentral gyrus- primary motor area.
Postcentral gyrus- primary somatosensory
area.
Commissural tracts- Corpus callosum:
Association tracts-
Projection tracts-
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Three nuclei deep within each cerebral
hemisphere make up basal ganglia.
They are globus pallidus, putamen, and
caudate nucleus.
Help initiate and terminate movements,
suppress unwanted movements and regulate
muscle tone.
A ring of structures on the inner border of the
cerebrum and floor of the diencephalon.
Includes cingulate gyrus, hippocampus,
dentate gyrus, amygdala, mammillary
bodies, thalamus, and the olfactory bulb.
“emotional brain” as it governs emotional
aspects of behavior.
Also involved in olfaction and memory.
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Primary motor area- precentral gyrus.
Broca’s speech area- left cerebral hemisphere.
Somatosensory association area- posterior to
primary somatosensory area.
Visual association area- occipital lobe.
Auditory association area- temporal lobe.
Wernicke’s area- left temporal and parietal
lobes.
Prefrontal cortex- anterior portion of the
frontal lobe.
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12 pairs.
Sensory, motor and mixed nerves.
Name as well as roman numeric numbers to
identify the nerves.
Sensory nerve.
Sense of smell.
Olfactory cells
converge to become
olfactory nerve.
Sensory nerve.
Ganglion cells in the
retina of each eye join
to form an optic nerve.
Nerve of vision.
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Motor cranial nerve.
Smallest of the 12
cranial nerves.
Origin: midbrain.
Controls movement of
the eyeball.
Largest cranial nerve.
Mixed nerve.
Three branches:
opthalmic, maxillary
and mandibular. Deal
with sensation of
touch, pain and
temperature.
Motor axons supply
muscles of mastication.
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Motor cranial nerve.
Originates from the
pons.
Cause abduction of the
eyeball (lateral
rotation).
Mixed cranial
nerve.
Sensory portion
extends from the
taste buds of the
anterior two-thirds
of the tongue.
Motor portion
arises from the
pons and deal with
facial expression.
Sensory cranial
nerve.
Originates in the
inner ear.
Vestibular branch
carries impulses
for equilibrium.
Cochlear branch
carries impulses
for hearing.
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Mixed cranial
nerve.
Sensory axons
carry signals from
the taste buds of
the posterior one-
third of the
tongue.
Motor neurons
arise from the
medulla and deal
with the release
of saliva.
Mixed cranial nerve.
Distributed from the head and neck into the
thorax and abdomen.
Sensory neurons deal with a variety of
sensations such as proprioception, and
stretching.
Motor neurons arise from the medulla and
supply muscles of the pharynx, larynx, and
soft palate that are involved in swallowing
and vocalization.
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Motor cranial
nerve.
Divided into cranial
accessory and
spinal accessory
nerves.
Supplies
sternocleidomastoi
d and trapezius
muscles to
coordinatehead
movements.
Motor cranial nerve.
Conduct nerve impulses for speech and swallowing.