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The Brain and Cranial Nerves
Ch. 19
Major Brain Subdivisions
• Cerebrum
• Diencephalon
– Hypothalamus and
Thalamus
• Brain Stem
– Midbrain, pons, medulla
oblongata
• Cerebellum
Cerebrum
• Processes:
– motor control, thoughts,
judgment, problem
solving, memory, and
language
• Left & Right Hemispheres
– longitudinal fissure
separates hemispheres
– Gyri: elevated ridges
– Sulci: shallow grooves
– Fissures: deeper grooves
Cerebrum
• Corpus callosum:
– Bundle of axon fibers that
enables communication
between the hemispheres
• Cerebral cortex:
outermost area of brain
– cell bodies of cerebral
neurons (gray matter)
• White matter:
– Made of fiber tracks
carrying impulses to or
from the cortex
Diencephalon
Consists of:
• Thalamus
– Translates information
for interpretation by
cerebral cortex
• Hypothalamus
– Translates electrical
signals into hormones
Brain Stem
Consists of:
• Midbrain
– connects the pons below
with the cerebrum above
• Pons
– means bridge
– motor and sensory fiber
tracts connecting or
bridging the brain to the
lower CNS
• Medulla oblongata
– lowest brain stem region.
It is composed mainly of
fiber tracts
Cerebellum
• Function:
– Coordination and
integration of
sensory input and
motor control
(controls balance
and equilibrium)
Meninges
• Brain and Spinal cord are protected by 3
connective tissue membranes
– Dura Mater
– Arachnoid Mater
– Pia Mater
Cerebral Spinal Fluid
• Fluid
– inside the brain found in ventricles
– Outside the brain is found in arachnoid layer
• Prevent brain from collapsing in on itself
• Shock absorption
Cranial Nerves
• Twelve pairs of cranial nerves arise from the
brain
• They have sensory, motor, or both sensory and
motor functions
• Each nerve is identified by a number (I
through XII) and a name
Functions of Nerves
I.
II.
III.
Olfactory - sense of smell
Optic - vision
Oculomotor Nerve - movement of eyelid and eyeball, constriction of
pupil and accommodation of lens for near vision
IV. Trochler Nerve - movement of eyeball
V. Trigeminal - chewing (motor) and sensory
VI. Abducens Nerve - lateral movement of eyeball
VII. Facial Nerve - Facial expression, taste, tears
VIII. Vestibulocochlear Nerve - hearing, equilibrium
IX. Glossopharyngeal Nerve - taste, swallowing, speech
X. Vagus Nerve - taste, swallowing, talking
XI. Accessory Nerve - swallowing, SCM, trapezius muscles (neck muscles)
XII. Hypoglossal Nerve - tongue movement
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Mnemonics for Cranial Nerves
1) On occasion our trusty truck acts funny -very good vehicle anyhow
2) Oh oh oh to touch and feel
very green vegetables ah
Summary of Function of Cranial
Nerves
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Figure 13.5b