The Brain and Cranial Nerves

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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
Some Say Marry Money But My Brother Says Big Brains Matter Most
Figure 13.5b
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