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Brain stem- continuation of 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 the ANS. 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 sternocleidomastoid and trapezius muscles to coordinate head movements.

Motor cranial nerve. Conduct nerve impulses for speech and swallowing.