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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.

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Presentation on theme: "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."— Presentation transcript:

1 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

2 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

3 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

4 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

5 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

6 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

7 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

8 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

9 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

10 Cranial Nerve II – Optic Nerve This nerve is tested by assessing a person’s vision. Above image from: Back to Cranial Nerve Index Wendy M. Rappazzo Harford Community College, July 2009

11 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, 8 th ed. Pearson, Benjamin Cummings Wendy M. Rappazzo Harford Community College, July 2009

12 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. Above image from: Back to Cranial Nerve Index Wendy M. Rappazzo Harford Community College, July 2009

13 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, 8 th ed. Pearson, Benjamin Cummings Wendy M. Rappazzo Harford Community College, July 2009

14 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, 8 th ed. Pearson, Benjamin Cummings Back to Cranial Nerve Index Wendy M. Rappazzo Harford Community College, July 2009

15 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

16 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

17 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

18 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

19 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 2009

20 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, 8 th ed. Pearson, Benjamin Cummings Wendy M. Rappazzo Harford Community College, July 2009

21 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, 8 th ed. Pearson, Benjamin Cummings Back to Cranial Nerve Index Wendy M. Rappazzo Harford Community College, July 2009

22 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

23 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

24 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 2009

25 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 p1004-uf1.gif p1004-uf1.gif Back to Cranial Nerve Index Wendy M. Rappazzo Harford Community College, July 2009

26 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

27 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. Back to Cranial Nerve Index Wendy M. Rappazzo Harford Community College, July 2009

28 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

29 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. Back to Cranial Nerve Index Wendy M. Rappazzo Harford Community College, July 2009

30 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, 8 th ed. Pearson, Benjamin Cummings Wendy M. Rappazzo Harford Community College, July 2009

31 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, 8 th ed. Pearson, Benjamin Cummings Wendy M. Rappazzo Harford Community College, July 2009

32 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

33 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. Back to Cranial Nerve Index Wendy M. Rappazzo Harford Community College, July 2009

34 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

35 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 2009

36 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

37 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

38 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

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41 Martini, F.H., & Nath, J.L. (2009). Fundamentals of Anatomy & Physiology. 8 th 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


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