Cranial Nerves - PowerPoint Presentation

Slide1

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 2009Slide2

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 2009Slide3

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 2009Slide4

Cranial Nerves

Cranial nerves can also be purely motor in function. Five cranial nerves are

motor nerves. These are

the:

O

cculomotor

Trochlear

Abducens

Accessory (spinal accessory)

Hypoglossal

Wendy M. Rappazzo Harford Community College, July 2009Slide5

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 2009Slide6

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 2009Slide7

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 2009Slide8

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 2009Slide9

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 2009Slide10

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

Back to Cranial Nerve Index

Wendy M. Rappazzo Harford Community College, July 2009Slide11

Cranial Nerve III -

OculomotorThe 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, 8

th

ed. Pearson, Benjamin Cummings

Wendy M. Rappazzo Harford Community College, July 2009Slide12

Cranial Nerve III -

OculomotorThis 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.

Above image from:

http://leavingbio.net/THE%20SENSES_files/THE%20SENSES_files/image016.jpg

Back to Cranial Nerve Index

Wendy M. Rappazzo Harford Community College, July 2009Slide13

Cranial Nerve IV -

TrochlearThe 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, 8

th

ed. Pearson, Benjamin Cummings

Wendy M. Rappazzo Harford Community College, July 2009Slide14

Cranial Nerve IV -

TrochlearThis 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, 8

th

ed. Pearson, Benjamin Cummings

Back to Cranial Nerve Index

Wendy M. Rappazzo Harford Community College, July 2009Slide15

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 2009Slide16

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 2009Slide17

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 2009Slide18

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 2009Slide19

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.

Motor function of this nerve is assessed by having the individual clench his/her teeth.

Ophthalmic

Maxillary

Mandibular

Back to Cranial Nerve Index

Wendy M. Rappazzo Harford Community College, July 2009Slide20

Cranial Nerve VI -

AbducensThe 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

ab

ducens

nerve because it

ab

ducts the eyeball.

Above image from

Marieb, Elaine Human Anatomy & Physiology, 8

th ed. Pearson, Benjamin Cummings

Wendy M. Rappazzo Harford Community College, July 2009Slide21

Cranial Nerve VI -

AbducensThis 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, 8

th

ed. Pearson, Benjamin Cummings

Back to Cranial Nerve Index

Wendy M. Rappazzo Harford Community College, July 2009Slide22

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 2009Slide23

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 2009Slide24

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, 8

th

ed. Pearson, Benjamin Cummings

Wendy M. Rappazzo Harford Community College, July 2009Slide25

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

http://www.aafp.org/afp/AFPprinter/20071001/afp20071001p1004-uf1.gif

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Wendy M. Rappazzo Harford Community College, July 2009Slide26

Cranial Nerve VIII –

VestibulocochlearThe 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 2009Slide27

Cranial Nerve VIII –

VestibulocochlearThe 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.

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Wendy M. Rappazzo Harford Community College, July 2009Slide28

Cranial Nerve IX –

GlossopharyngealThe 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 2009Slide29

Cranial Nerve IX –

GlossopharyngealThe glossopharyngeal

nerve also carries somatic information to muscles of the pharynx for swallowing and autonomic (parasympathetic) motor information to the salivary glands.

Back to Cranial Nerve Index

Wendy M. Rappazzo Harford Community College, July 2009Slide30

Cranial Nerve X –

VagusThe 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, 8

th

ed. Pearson, Benjamin Cummings

Wendy M. Rappazzo Harford Community College, July 2009Slide31

Cranial Nerve X –

VagusIts 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, 8

th

ed. Pearson, Benjamin Cummings

Wendy M. Rappazzo Harford Community College, July 2009Slide32

Cranial Nerve X –

VagusThe 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 2009Slide33

Cranial Nerve X –

VagusTesting 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.

Back to Cranial Nerve Index

Wendy M. Rappazzo Harford Community College, July 2009Slide34

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 2009Slide35

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.

Above image from

Marieb

, Elaine Human Anatomy & Physiology, 8

th

ed. Pearson, Benjamin Cummings

Back to Cranial Nerve Index

Wendy M. Rappazzo Harford Community College, July 2009Slide36

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 2009Slide37

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 2009Slide38

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 2009Slide39

Wendy M. Rappazzo Harford Community College, July 2009Slide40

Wendy M. Rappazzo Harford Community College, July 2009Slide41

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. 8

th

edition. New York: Pearson, Benjamin Cummings.

Marieb. (2008). Human Anatomy & Physiology Laboratory Manual, Main Version. 8

th

edition. New York: Pearson, Benjamin Cummings.

Wendy M. Rappazzo Harford Community College, July 2009