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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 somatosensory area- postcentral
gyrus.
 Primary visual area- occipital lobe.
 Primary auditory area- temporal lobe.
 Primary gustatory area- base of the
postcentral gyrus.
 Primary olfactory area- temporal lobe.

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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.