Textbook Question
Mr. Spencer suffers loss of taste sensation. Tests reveal that his taste buds and salivary glands are functional. What other structures might be impaired that would explain his loss of taste?
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Ch. 15 The Special Senses
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology24
- Ch. 2 The Chemistry of Life37
- Ch. 3 The Cell54
- Ch. 4 Histology46
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System35
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System41
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomic Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart28
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity41
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Metabolism and Nutrition7
- Ch. 24 The Urinary System39
- Ch. 25 Fluid, Electrolyte, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814Not the one you use?Change textbook
Chapter 15, Problem L3.6
Your 60-year-old patient, Mr. Guster, has Bell's palsy, which causes dysfunction of those portions of the facial nerve that control muscles of facial expression. He is surprised when you tell him to tape the eyelids of his right eye closed at night to prevent dryness. Why might Bell's palsy cause dryness of the eye on the affected side?
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Understand that Bell's palsy is a condition that affects the facial nerve (cranial nerve VII), which controls muscles of facial expression and has additional roles in tear production and eyelid closure.
Recognize that the facial nerve also innervates the orbicularis oculi muscle, which is responsible for closing the eyelids. Dysfunction of this nerve can lead to an inability to fully close the eyelid on the affected side.
Explain that when the eyelid cannot close properly, the eye is exposed to the environment for extended periods, leading to reduced protection and increased evaporation of the tear film, which causes dryness.
Note that the facial nerve also plays a role in stimulating the lacrimal gland to produce tears. If this function is impaired, tear production may be reduced, further contributing to dryness of the eye.
Conclude that taping the eyelid closed at night helps protect the eye from exposure and prevents excessive dryness by maintaining moisture and reducing evaporation during sleep.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Facial Nerve Function
The facial nerve (cranial nerve VII) is responsible for controlling the muscles of facial expression, as well as providing sensory functions and autonomic functions such as tear production. In Bell's palsy, inflammation or damage to this nerve can lead to weakness or paralysis of the facial muscles, affecting the ability to blink and close the eye properly, which can result in dryness.
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Overview of Facial Bones
Tear Production and Distribution
Tears are produced by the lacrimal glands and are essential for maintaining eye moisture and health. The facial nerve plays a role in stimulating these glands. When Bell's palsy affects the facial nerve, it can disrupt the normal production and distribution of tears, leading to dryness in the affected eye due to inadequate lubrication.
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Protective Mechanisms of the Eye
The eyelids serve as a protective barrier for the eyes, helping to keep them moist and shielded from environmental irritants. In cases of Bell's palsy, the inability to fully close the eyelid on the affected side can expose the cornea to air and debris, increasing the risk of dryness and potential damage, necessitating measures like taping the eyelid closed at night.
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Related Practice
Textbook Question
The primary olfactory cortex is located in the:
a. Frontal lobe
b. Occipital lobe
c. Parietal lobe
d. Temporal lobe
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Textbook Question
Suppose the round window in your middle ear became very stiff. What effect would this have on hearing, and why?
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Textbook Question
If severe congestion from a cold prevented your pharyngotympanic tube from opening, what could happen to your tympanic membrane? Explain your answer.
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Textbook Question
Your friend tells you that she has just been diagnosed with myopia, and she wonders if staring at her computer screen too much might have caused her problem. What do you tell her?
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Textbook Question
Mrs. Flores is a 45-year-old female who suffered a fracture of the ethmoid bone as the result of a car accident. Several days later, she complained that she couldn't taste her food very well. How is her injury related to the loss of taste sensation?
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