Cranial Nerves
• This tutorial will allow you to learn about the
12 pairs of cranial nerves in the human body.
• An introduction to the cranial nerves is
followed by a screen which allows you to click
on the nerve name to learn the functions and
tests for the assessment for each nerve.
• At the end is a review exercise for you to write
up.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerves
There are 12 pairs of
cranial nerves.
They emerge from the
inferior portion of the
brain.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerves
Cranial nerves can be
purely sensory in
function. Three cranial
nerves are sensory
nerves. These are the:
Olfactory
Optic &
Vestibulocochlear
(auditory) nerves
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerves
Cranial nerves can also be
purely motor in function.
Five cranial nerves are
motor nerves. These are
the:
Occulomotor
Trochlear
Abducens
Accessory (spinal accessory)
Hypoglossal
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerves
Some cranial nerves are
mixed nerves, like spinal
nerves. Four cranial
nerves are mixed
nerves. These are the:
Trigeminal
Facial
Glossopharyngeal
Vagus
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerves
Click on the cranial nerve
name from the list below
to study it in more detail.
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Accessory
Hypoglossal
Conclusion & Review Questions
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve I - Olfactory
The Olfactory nerve is a
sensory nerve.
It functions to bring sensory
information from the
olfactory receptors in the
nasal cavity to the brain.
The olfactory nerves begin
as bundles and pass
through the cribriform
plate to get to the brain.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve I - Olfactory
This nerve is tested by
assessing the ability to
smell and identify different
substances. Try this with
coffee, vanilla, lemon, and
cologne.
Back to Cranial
Nerve Index
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve II - Optic Nerve
The Optic nerve is a sensory
nerve.
It functions to bring sensory
information from the
retina to the brain. It
passes through the optic
canal of the sphenoid
bone to get to the brain.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve II – Optic Nerve
This nerve is tested by
assessing a person’s
vision.
Above image from: http://www.eyecaretyler.com/art/chart.gif
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Nerve Index
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve III - Oculomotor
The Oculomotor nerve is a
motor nerve.
It functions to bring somatic
motor information to the
eye muscles & upper
eyelid from the brain. It
also controls the iris via
autonomic motor axons.
It passes through the
superior orbital fissure to
reach these muscles.
Above image from Marieb, Elaine Human Anatomy &
Physiology, 8th ed. Pearson, Benjamin Cummings
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve III - Oculomotor
This nerve is tested by
having a person follow an
object with their eyes.
The autonomic portion is
easily tested via the pupil
reflex. A penlight is used
to shine light at the pupil,
the pupil should constrict
in response to bright
light.
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Nerve Index
Above image from: http://leavingbio.net/THE%20SENSES_files/THE%20SENSES_files/image016.jpg
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve IV - Trochlear
The Trochlear nerve is a
motor nerve.
It functions to bring motor
information from the brain
to the superior oblique eye
muscle. It passes through
the superior orbital fissure
to enter the orbit of the
eye.
Above image from Marieb, Elaine Human Anatomy &
Physiology, 8th ed. Pearson, Benjamin Cummings
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve IV - Trochlear
This nerve is tested with the
occulomotor & abducens
nerves by following an
object with your eyes. If
you hold a finger in front of
the individual, move it up
and down, then left and
right and see if their eye
can follow the movements.
Above image from Marieb, Elaine Human Anatomy &
Physiology, 8th ed. Pearson, Benjamin Cummings
Back to Cranial
Nerve Index
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve V - Trigeminal
The Trigeminal nerve is a
mixed nerve. It carries
both sensory and motor
information.
It is a large nerve that
consists of three branches:
1.) Opthalmic
2.) Maxillary
3.) Mandibular
Each branch will be discussed
individually.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve V - Trigeminal
The Opthalmic branch is
sensory. It functions to
carry sensory information
(touch) from the cornea,
orbit, upper eyelid,
eyebrow, and part of the
nose to the brain. It passes
through the superior
orbital fissure to reach the
brain.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve V - Trigeminal
The Maxillary branch is
sensory. It functions to
carry sensory information
(touch) from the lower
eyelid, upper lip, gums,
teeth, cheek, & nose to the
brain. It passes through
the foramen rotundum of
the sphenoid bone to
reach the brain.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve V - Trigeminal
The Mandibular branch is
both sensory & motor. It
functions to carry sensory
information (touch) from
the lower lip, gums & teeth
to the brain. Its motor
function is to the muscles
of mastication. It passes
through the foramen ovale
of the sphenoid bone to
reach the brain.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve V - Trigeminal
This nerve is tested by touching
the areas of the face & gums
associated with each branch.
The corneal reflex is also
used to test this nerve.
Touching the cornea with
cotton should cause blinking
to occur.
Ophthalmic
Maxillary
Motor function of this nerve is
assessed by having the
individual clench his/her
teeth.
Wendy M. Rappazzo
Harford Community College, July 2009
Mandibular
Back to Cranial
Nerve Index
Cranial Nerve VI - Abducens
The Abducens nerve is a
motor nerve.
It functions to bring motor
information from the brain
to the lateral rectus eye
muscle. It passes through
the superior orbital fissure
to the eye. It is named the
abducens nerve because it
abducts the eyeball.
Above image from Marieb, Elaine Human Anatomy &
Physiology, 8th ed. Pearson, Benjamin Cummings
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve VI - Abducens
This nerve is tested with the
occulomotor & trochlear
nerves by following an
object with your eyes. If
you hold a finger in front of
the individual, move it up
and down, then left and
right and see if the eye can
follow the movements.
Above image from Marieb, Elaine Human Anatomy &
Physiology, 8th ed. Pearson, Benjamin Cummings
Back to Cranial
Nerve Index
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve VII - Facial
The Facial nerve is a mixed
nerve. It carries sensory and
both somatic & autonomic
(parasympathetic) motor
information.
It is a large nerve that consists
of five branches:
1.) Temporal
2.) Zygomatic
3.) Buccal
4.) Mandibular
4.) Cervical
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve VII - Facial
Sensory functions of the
facial nerve include taste
(from the anterior 2/3 of
the tongue) and sense of
touch from the various
regions of the face.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve VII - Facial
Somatic motor functions of
the facial nerve are shown
by the ability to move the
muscles of the face to
smile, frown, and whistle.
The autonomic motor
functions carried by this
nerve innervate the
lacrimal glands to cause
tears.
Above image from Marieb, Elaine Human Anatomy &
Physiology, 8th ed. Pearson, Benjamin Cummings
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve VII - Facial
Bell’s Palsy is a disorder that
results in an inflammation of
the facial nerve. This
condition often causes
paralysis of the affected side
(facial drooping) and a loss of
taste from the anterior
region of the tongue.
The exact cause of this is not known but it
is thought to result from a viral infection,
such as herpes simplex.
Above image from
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Nerve Index
http://www.aafp.org/afp/AFPprinter/20071001/afp20071001
p1004-uf1.gif
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve VIII – Vestibulocochlear
The vestibulocochlear nerve
is a sensory nerve. It is
also known as the auditory
or acoustic nerve.
It functions to bring sensory
information from the
hearing and equilibrium
receptors in the inner ear
to the brain. It has 2 main
branches:
1.) cochlear (hearing)
2.) vestibular (equilibrium)
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve VIII – Vestibulocochlear
The vestibulocochlear nerve
passes through the internal
acoustic canal (meatus) to
enter the brain.
This nerve is tested by
conducting hearing tests.
In a quiet room see if you
can hear the ticking of a
watch and identify where it
is.
Wendy M. Rappazzo
Harford Community College, July 2009
Back to Cranial
Nerve Index
Cranial Nerve IX – Glossopharyngeal
The glossopharyngeal is a mixed
nerve that passes through
the jugular foramen to the
brain.
This nerve transports sensory
information from taste
receptors on the posterior
1/3 of the tongue & pharynx.
It also relays chemoreceptor
information from the carotid
sinus in the carotid artery to
control blood pressure.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve IX – Glossopharyngeal
The glossopharyngeal nerve
also carries somatic
information to muscles of
the pharynx for
swallowing and
autonomic
(parasympathetic) motor
information to the salivary
glands.
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Nerve Index
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve X – Vagus
The vagus nerve is a mixed
nerve. It transports
sensory and autonomic
(parasympathetic) motor
information
It passes through the jugular
foramen to enter/exit the
brain.
Above image from Marieb, Elaine Human Anatomy & Physiology, 8th ed. Pearson, Benjamin Cummings
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve X – Vagus
Its sensory function is to
transport information for
taste from the pharynx and
sensory information from the
visceral organs of the thoracic
and abdominopelvic cavities.
It also brings baroreceptor &
chemoreceptor information
from the aortic body in the
aortic arch to the medulla
oblongata to control HR & BP.
Above image from Marieb, Elaine Human Anatomy & Physiology, 8th ed. Pearson, Benjamin Cummings
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve X – Vagus
The vagus nerve is a critical
nerve for supplying
parasympathetic
information to the visceral
organs of the respiratory,
digestive and urinary
systems. It is important in
the control of heart rate,
bronchoconstriction &
digestive processes.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve X – Vagus
Testing for the proper
functioning of the vagus
nerve is accomplished by
seeing if the individual has
any difficulty swallowing.
Also measuring HR can
provide additional
information about the
function of this nerve.
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Nerve Index
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve XI – Accessory
The Accessory (Spinal
Accessory) nerves are motor
nerves. They have roots that
begin on the cervical
segments of the spinal cord.
The roots travel up through
the foramen magnum and
join cranial fibers to form
the accessory nerve which
then pass through the
jugular foramen to carry
somatic motor information
to skeletal muscles of the
neck and upper back.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve XI – Accessory
Testing the function of the
accessory nerve is simple.
Since it innervates the
trapezius and
sternocleidomastoid
muscles, you can check this
by having the individual
shrug their shoulders and
turn their head/neck.
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Nerve Index
Above image from Marieb, Elaine Human Anatomy & Physiology, 8th
ed. Pearson, Benjamin Cummings
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve XII – Hypoglossal
The Hypoglossal nerve is a
motor nerve that innervates
the tongue.
It passes through the
hypoglossal canal of the
occipital bone to travel to
the muscles of the tongue.
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerve XII – Hypoglossal
This nerve is tested by having
the individual stick their
tongue out and move it.
Back to Cranial
Nerve Index
Wendy M. Rappazzo
Harford Community College, July 2009
Cranial Nerves
In conclusion, the cranial
nerves consist of 12
pairs of nerves that
have critical functions
for sensory, somatic and
autonomic motor
control over the body.
The next slide contains a
cranial nerve review to
test your knowledge of
the cranial nerves
Wendy M. Rappazzo
Harford Community College, July 2009
Wendy M. Rappazzo
Harford Community College, July 2009
Wendy M. Rappazzo
Harford Community College, July 2009
Martini, F.H., & Nath , J.L. (2009). Fundamentals of Anatomy & Physiology.
8th ed. New York: Pearson, Benjamin Cummings.
Marieb, E.N., & Hoehn, K. (2010). Human Anatomy & Physiology. 8th
edition. New York: Pearson, Benjamin Cummings.
Marieb. (2008). Human Anatomy & Physiology Laboratory Manual, Main
Version. 8th edition. New York: Pearson, Benjamin Cummings.
Wendy M. Rappazzo
Harford Community College, July 2009