The special senses are smell, taste, vision, hearing, and equilibrium. They are called special senses because their sensory receptors are located within relatively large sensory organs in the head—the nose, tongue, eyes, and ears. Although the skin is also considered a sense organ, in fact it is the largest sense organ, touch is not considered a special sense but a generalized one (refer to Ch. 24, The Integumentary System). As you read this chapter, keep in mind that no matter how a stimulus starts, it is sent, via the nervous system, to the brain for interpretation (and then reaction, if necessary). This chapter introduces the structure and function of the special sense organs.

As a medical assistant, it is likely that you will be asked to assist with or perform examinations and treatments for common disorders of the eyes and ears. Therefore, you will need to understand the functioning of these important sense organs.

Outline

• The Nose and the Sense of Smell
• The Tongue and the Sense of Taste
• The Eye and the Sense of Sight
• The Aging Eye
• Vision Testing
• Treating Eye Problems
• The Ear and the Senses of Hearing and Equilibrium
• The Aging Ear
• Hearing Loss
• Hearing and Diagnostic Tests
• Treating Ear and Hearing Problems

Learning Outcomes

After completing Chapter 35, you will be able to:

 35.1 Describe the anatomy of the nose and the function of each part.
 35.2 Describe how smell sensations are created and interpreted.
 35.3 Describe the anatomy of the tongue and the function of each part.
 35.4 Describe how taste sensations are created and interpreted.
 35.5 Name the four primary taste sensations and the acknowledged fifth taste sensation.
 35.6 Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions.
 35.7 Trace the visual pathway through the eye and to the brain for interpretation.
 35.8 Identify ways that patients can practice preventive eye care.
 35.9 State ways that vision changes with age.
 35.10 List the medical professionals involved in diagnosis and treatment of visual disorders, including the roles that each plays in patient care.
 35.11 List treatments for visual disorders.
 35.12 Describe the causes, signs and symptoms, and treatments of various diseases and conditions of the eye.
 35.13 Describe the anatomy of the ear and the function of each part.
 35.14 Explain the role of the ear in maintaining equilibrium.
 35.15 Explain how sounds travel through the ear and are interpreted in the brain.
 35.16 State ways that hearing changes with age.
 35.17 List the types of hearing loss and how they differ.
 35.18 Describe treatments for ear and hearing disorders.
 35.19 Explain how patients can be educated about preventive ear care.
 35.20 Describe the causes, signs and symptoms, and treatments of various disorders of the ear and hearing.

Summary

The ability to detect changes in the environment is critical to survival. The human body has various organs for this purpose. The nose senses odors in the environment and the tongue senses tastes. The eyes allow us to visualize our environment and our ears to hear. Each of these special senses works in concert with the nervous system to assist the body in coping with environmental changes experienced throughout the day.

You can help prevent, detect, and treat eye and ear problems in your work as a medical assistant. Because conditions that affect the eyes and ears can have an impact on vision, hearing, and balance, these conditions affect a patient's quality of life. Vision and hearing provide people with information about the world around them; balance allows people to move securely and effectively through their environment.