Medical Terminology Sensory System PDF

PART XV CHAPTER 15 SENSORY SYSTEM TERMINOLOGY Chapter 15 Sensory System Terminology | 827 828 | Chapter 15 Sensory System Terminology 15.1 Sensory System Introduction Learning Objectives Apply the rules of medical language to build, analyze, spell,...

PART XV CHAPTER 15 SENSORY SYSTEM TERMINOLOGY Chapter 15 Sensory System Terminology | 827 828 | Chapter 15 Sensory System Terminology 15.1 Sensory System Introduction Learning Objectives Apply the rules of medical language to build, analyze, spell, pronounce, abbreviate, and define terms as they relate to the sensory system Identify meanings of key word components of the sensory system Categorize diagnostic, therapeutic, procedural, or anatomic terms related to the sensory system Use terms related to the sensory system Use terms related to the diseases and disorders of the sensory system Introduction to the Sensory Systems Most people consider the five major senses to be taste, smell, touch, hearing, and sight. These are referred to as the “special senses” because they have organs devoted to the senses, such as the eye, ear, tongue, and nose. This chapter will review common word components related to the systems of special senses to assist learners in analyzing, building, and defining medical terms. Other terms, whose definitions cannot be easily built from word components, will be described in context based on the anatomy and physiology of sensory systems and common diseases and disorders. Medical 15.1 Sensory System Introduction | 829 specialists, diagnostic tests, and procedures related to sensory systems will also be discussed. 830 | 15.1 Sensory System Introduction 15.2 Word Components Related to the Sensory Systems This section will describe common word components related to the sensory systems. These word components help build definitions for many medical terms. Other common prefixes are described in Chapter 1.3, and common suffixes are described in Chapter 1.5. PREFIXES RELATED TO THE SENSORY SYSTEMS a- or an-: Absence of, without, no, or not (negates meaning) bi-: Two bin-: Two endo-: Within, in WORD ROOTS WITH A COMBINING VOWEL RELATED TO THE SENSORY SYSTEMS acous/o: Hearing 15.2 Word Components Related to the Sensory Systems | 831  audi/o: Hearing audit/o: Hearing aur/i or aur/o: Ear blephar/o: Eyelid cochle/o: Cochlea conjunctiv/o: Conjunctiva cor/o: Pupil core/o: Pupil corne/o: Cornea cry/o: Cold cyst/o: Bladder, sac, or cyst dacry/o: Tear, tear duct dipl/o: Two, double ir/o: Iris irid/o: Iris is/o: Equal kerat/o: Cornea labyrinth/o: Labyrinth, inner ear lacrim/o: Tear, tear duct mastoid/o: Mastoid bone myring/o: Tympanic membrane ocul/o: Eye ophthalm/o: Eye opt/o: Vision ossicul/o: Ossicle ot/o: Ear phac/o: Lens phak/o: Lens phot/o: Light pupill/o: Pupil retin/o: Retina salping/o: Tube scler/o: Sclera staped/o: Stapes, middle ear 832 | 15.2 Word Components Related to the Sensory Systems  ton/o: Tension, pressure tympan/o: Middle ear, tympanic membrane vestibul/o: Vestibule xer/o: Dry SUFFIXES RELATED TO THE SENSORY SYSTEMS -al: Pertaining to -algia: Pain -ar: Pertaining to -ary: Pertaining to -eal: Pertaining to -ectomy: Excision or surgical removal -gram: Record, radiographic image -graphy: Process of recording -ia: Condition of, diseased or abnormal state -ic: Pertaining to -itis: Inflammation -logist: Specialist who studies and treats -logy: Study of -malacia: Softening -meter: Instrument used to measure -metry: Process of measuring -oma: Tumor, swelling -opia: Vision as it relates to condition -osis: Abnormal condition -pathy: Disease -pexy: Surgical fixation -phobia: Abnormal fear, aversion to specific things -plasty: Surgical repair 15.2 Word Components Related to the Sensory Systems | 833  -plegia: Paralysis -ptosis: Prolapse, drooping, sagging -rrhea: Flow, discharge -sclerosis: Hardening -scope: Instrument used to view -scopy: Process of viewing -stomy: Creation of artificial opening -tomy: Incision, cut into 834 | 15.2 Word Components Related to the Sensory Systems 15.3 Examples of Sensory Terms Easily Defined By Their Word Components Here are examples of common medical terms related to the sensory systems that can be easily defined by breaking the terms into their word components. Audiologist 1. Break down the medical term into word components: Audi/o/logist 2. Label the word components: Audi = WR; o = CV; logist = S 3. Define the word components: Audi = hearing; logist = physician who specializes in diagnosing and treating 4. Create a final definition of the medical term: Specialist who diagnoses and treats hearing Ophthalmoscopy 1.Break down the medical term into word components: Ophthalm/o/scopy 2. Label the word components: Ophthalm = WR; o = CV; scopy = S 3. Define the word components: Ophthalm = eye; scopy 15.3 Examples of Sensory Terms Easily Defined By Their Word Components | 835  = process of viewing 4. Create a final definition of the medical term: Process of viewing the eye Tympanoplasty 1.Break down the medical term into word components: Tympan/o/plasty 2. Label the word components: Tympan = WR; o = CV; plasty =S 3. Define the word components: Tympan = tympanic membrane; plasty = surgical repair 4. Create a final definition of the medical term: Surgical repair of the tympanic membrane Interactive Learning Activity: Practice defining and pronouncing sensory system medical terms by breaking them into word parts. An interactive H5P element has been excluded from this version of the text. You can view it online here: https://wtcs.pressbooks.pub/medterm/?p=6081#h5p-62 You can also print these flashcard activities as a Chapter 15 836 | 15.3 Examples of Sensory Terms Easily Defined By Their Word Components Student Companion Worksheet and check your answers with this Answer Key. 15.3 Examples of Sensory Terms Easily Defined By Their Word Components | 837  15.4 Anatomy and Physiology of the Sensory Systems VISION Vision is the special sense of sight based on the transduction of light stimuli 1 received through the eyes. See Figure 15.1 for an illustration of the eye. The bony orbits surround the eyeballs, protecting them and anchoring the soft tissues of the eye. The eyelashes and eyelids help protect the eye by blocking 2 particles from landing on the surface of the eye. Figure 15.1 The Eye 1. “1411_Eye_in_The_Orbit.jpg” by OpenStax College is licensed under CC BY 3.0 2. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 838 | 15.4 Anatomy and Physiology of the Sensory Systems  The inner surface of each lid is a thin membrane known as the conjunctiva (kŏn-jŭnk-TI-va). The conjunctiva extends over the white areas of the eye called the sclera (sklĕr-ă), connecting the eyelids to the eyeball. The iris (ir-ĭs) is the colored part of the eye. The iris is a smooth muscle that opens and closes the pupil (pū-pĭl), the hole at the center of the eye that allows light to enter. The iris constricts the pupil in response to bright light and dilates the pupil in response to dim light. The cornea (KOR-nē-ă) is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. The cornea, with the anterior chamber and lens, refracts light and contributes to vision. The innermost layer of the eye is the retina (RĔT-ĭ-nă). The retina contains the nervous tissue and specialized cells called photoreceptors for the initial processing of visual stimuli. These nerve cells of the retina leave the eye and 3 enter the brain via the optic nerve (OP-tik nerve). See Figure 15.2 for an 4 illustration of these structures of the eye. Figure 15.2 Structures of the Eye Tears are produced by the lacrimal gland (LAK-rĭ-măl gland) that is located 3. “1413_Structure_of_the_Eye.jpg” by OpenStax College is licensed under CC BY 3.0 4. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 15.4 Anatomy and Physiology of the Sensory Systems | 839  beneath the lateral edges of the nose. Tears are continuously produced by the lacrimal duct and secreted through a duct onto the surface of the eye to wash away foreign particles. Movement of the eye occurs by the contraction of six voluntary extraocular extrinsic muscles that originate from the bones of the 5 orbit and insert into the surface of the eyeball. 6 View a supplementary YouTube video from Crash Course on vision: Vision: Crash Course Anatomy & Physiology #18 AUDITORY Hearing is a special sense based on the transduction of sound waves into a neural signal that is made possible by the structures of the ear. See Figure 7 8 15.3 for an illustration of the ear structures. 5. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 6. CrashCourse. (2015, May 11). Vision: Crash Course Anatomy & Physiology #18 [Video]. YouTube. All rights reserved. https://www.youtube.com/watch?v=o0DYP-u1rNM 7. “5dfc7e834c03e3e7dbbf82de10413b92379a1a57.png” by Clark, et al., is licensed under CC BY 4.0. Access for free at https://openstax.org/books/biology-2e/pages/1-introduction. 8. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 840 | 15.4 Anatomy and Physiology of the Sensory Systems  Figure 15.3 Structures of the Ear The large, fleshy structure on the lateral aspect of the head is the auricle (AW- rĭ-kl), also known as the pinna (PĬN-ă). The C-shaped curves of the auricle direct sound waves toward the ear canal. At the end of the ear canal is the tympanic membrane (tĭm-păn-ik mem-brān), commonly referred to as the eardrum, that vibrates from sound waves. The auricle, ear canal, and 9 tympanic membrane are referred to as the external ear. The middle ear consists of a space with three small bones called the malleus, incus, and stapes, the Latin names that roughly translate to “hammer,” “anvil,” and “stirrup.” The malleus (MĂL-ē-ŭs) is attached to the tympanic membrane and articulates with the incus. The incus (ĬN-kŭs), in turn, articulates with the stapes. The stapes (stā-pēz) is attached to the inner ear, where the sound waves are converted into a neural signal. The middle ear is also connected to the pharynx through the Eustachian tube (yōō-STĀ-shən tūb) that helps equalize air pressure across the tympanic membrane. The 9. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 15.4 Anatomy and Physiology of the Sensory Systems | 841  Eustachian tube is normally closed but will pop open when the muscles of 10 the pharynx contract during swallowing or yawning. The inner ear (IN-er ĒR) is often described as a bony labyrinth because it is composed of a series of semicircular canals. The semicircular canals have two separate regions called the cochlea (KŎK-lē-ă) and the vestibule (ves-tĭ-būl) that are responsible for hearing and balance. The neural signals from these two regions travel together from the inner ear to the brain via the 11 vestibulocochlear nerve (ves-tĭ-būl-ō-KŌ-klē-ar nerve). See Figure 15.4 for an illustration of the transmission of sound from the outer ear to the middle ear 12 and to the inner ear. Figure 15.4 Pathway of Sound Vibrations 10. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 11. “Outer_Ear.jpg" by Nzachariah3 and is licensed under CC BY 3.0 12. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 842 | 15.4 Anatomy and Physiology of the Sensory Systems  Hearing The cochlea encodes auditory stimuli for frequencies between 20 and 20,000 Hz, which is the range of sound that human ears can detect. The hair cells along the length of the cochlear duct, which are each sensitive to a particular frequency, allow the cochlea to separate auditory stimuli by frequency, just as 13 a prism separates visible light into its component colors. See Figure 15.5 for 14 an illustration of the cochlea. Figure 15.5 Cochlea Balance Along with hearing, the inner ear is also responsible for the sense of balance. There are three semicircular canals (superior, posterior, and lateral) extending from the vestibule filled with fluid that work to maintain balance. Hair cells within the vestibule sense head position, head movement, and body motion. Medical conditions affecting the semicircular canals cause incorrect balance signals to be sent to the brain, resulting in a spinning type of dizziness called 15 vertigo (VUR-tĭ-gō). 13. “1406_Cochlea.jpg” by OpenStax College is licensed under CC BY 4.0 14. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 15. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 15.4 Anatomy and Physiology of the Sensory Systems | 843  16 View a supplementary YouTube video from Crash Course on hearing and balance: Hearing & Balance: Crash Course Anatomy & Physiology #17 TASTE Taste is the special sense associated with the tongue. The surface of the tongue contains raised bumps called papillae that contain the structures for taste transmission. Within the structure of the papillae are taste buds that contain specialized receptor cells for the transduction of taste stimuli. These receptor cells are sensitive to the chemicals contained within foods that are ingested, and they release neurotransmitters based on the amount of the chemical in the food. Until recently, only four tastes were recognized: sweet, salty, sour, and bitter. Recent research has suggested that there may also be additional tastes for fats and glutamates (tomatoes, cheese, and 17 mushrooms). SMELL Olfaction (smell) is a special sense based on receptors in a small region of the nasal cavity that are responsive to chemical stimuli. Scent receptor messages 16. CrashCourse. (2015, May 4). Hearing & balance: Crash Course Anatomy & Physiology #17 [Video]. YouTube. All rights reserved. https://www.youtube.com/watch?v=Ie2j7GpC4JU 17. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 844 | 15.4 Anatomy and Physiology of the Sensory Systems  travel to the brain, where smells are interpreted and can even become 18 associated with long-term memories and emotional responses. See Figure 19 15.6 for an illustration of olfaction. In this illustration, the olfactory bulb (1) contains mitral cells (2) that receive information from the olfactory cells (3). The olfactory cells are found within the nasal epithelium (4) and pass their information through the cribriform plate (5) of the ethmoid bone. Figure 15.6 Olfaction 18. This work is a derivative of Anatomy & Physiology by OpenStax and is licensed under CC BY 4.0. Access for free at https://openstax.org/details/books/anatomy-and-physiology-2e 19. “Cenveo - Drawing Anatomy of the Structures Involved in Smell (Olfaction) - Numbered labels” by Cenveo is licensed under CC BY 4.0 15.4 Anatomy and Physiology of the Sensory Systems | 845  20 View a supplementary YouTube video from Crash Course on taste and smell: Taste & Smell: Crash Course Anatomy & Physiology #16 TOUCH Touch is considered a general sense, as opposed to the special senses that were previously discussed in this section. Many of the receptors for touch are located in the skin, but receptors are also found in muscles, tendons, joint capsules, ligaments, and in the walls of visceral organs. These receptors detect sensations such as pressure, vibration, light touch, tickle, itch, temperature, pain, and proprioception (i.e., the sense of location, movement, 21 and action of our body parts). 20. CrashCourse. (2015, April 27). Taste & smell: Crash Course Anatomy & Physiology #16 [Video]. YouTube. All rights reserved. https://www.youtube.com/watch?v=mFm3yA1nslE 21. This work is a derivative of Anatomy and Physiology by OpenStax licensed under CC BY 4.0. Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction 846 | 15.4 Anatomy and Physiology of the Sensory Systems  15.5 Diseases and Disorders Related to the Sensory Systems EYE DISEASES AND DISORDERS Astigmatism Astigmatism (ă-STIG-mă-tizm) refers to blurry vision due to the irregular curvature of the cornea or lens. It is treated with corrective glasses or contact lenses. Blindness The term “blindness” covers a broad spectrum of visual impairments due to injury, disease, or a congenital condition. Total blindness (TŌ-tăl BLĪND-nĕss) is a term used to describe those who have complete lack of light perception. Low vision (LŌ VIZH-ŭn) is a term used to describe those individuals whose vision cannot be fully corrected by conventional methods such as glasses, contact lenses, medicine, surgery, magnification aids, or assistive technology. Visual impairment (VIZH-ŭ-al Im-PĀR-mĕnt) is a term used to describe decreased visual function that interferes with an individual’s ability to perform activities of daily living, such as reading, driving, and watching TV. Legal blindness (LĒ-găl BLĪND-nĕss), a term used for establishing disability benefits and rehabilitation training, refers to visual acuity (VIZH-u-ăl ă-KŪ-ĭt-ē) (VA) of 1 20/200 or less in the best-seeing eye after correction. 1. This work is a derivative of StatPearls by Lee & Mesfin and is licensed under CC BY 4.0 15.5 Diseases and Disorders Related to the Sensory Systems | 847  Cataract A cataract (KAT-ă-rakt) is a progressive disease of the lens that causes cloudiness and a lack of transparency. Cataracts are very common in older adults. Over half of all Americans aged 80 or older either have cataracts or 2 have had surgery to remove cataracts. See Figure 15.7 for an image of a cataract. Cataracts develop slowly, and symptoms include faded colors, blurred or double vision, halos around light, and trouble seeing at night. See 3 Figure 15.8 for a simulated image of a person’s vision who has cataracts. Decreased vision due to cataracts may result in trouble reading and driving and increases the risk of falling. Patients often undergo surgery for cataracts. During cataract surgery, the doctor removes the clouded lens and replaces it 4 with a new, artificial lens. Figure 15.7 Cataract 2. “Cataract in human eye.png” by Rakesh Ajuja, MD is licensed under CC BY-SA 3.0 3. “Eye disease simulation, cataract.jpg” by National Eye Institute, National Institutes of Health is in the Public Domain. 4. National Eye Institute. (2023, November 15). Cataracts. National Institutes of Health. https://www.nei.nih.gov/learn- about-eye-health/eye-conditions-and-diseases/cataracts 848 | 15.5 Diseases and Disorders Related to the Sensory Systems  Figure 15.8 Simulated Vision With Cataracts Color Blindness Color blindness, also called color vision deficiency, makes it difficult to differentiate between certain colors. Color blindness tends to run in families as a genetic condition, but it can also occur due to damage to the eye or to the brain. There’s no cure for color blindness, but special glasses and contact lenses can help people differentiate between colors. Most people who have color blindness are able to use visual strategies related to color selection and 5 don’t have problems participating in everyday activities. Conjunctivitis Conjunctivitis (kŏn-jŭnk-tĭ-VĪT-ĭs) is a viral or bacterial infection that causes 6 swelling and redness in the conjunctiva and sclera. See Figure 15.9 for an image of conjunctivitis. The eye may feel itchy and painful with crusty yellow drainage present. Bacterial conjunctivitis is treated with antibiotic eye drops. 7 Viral conjunctivitis is typically mild and resolves on its own. 5. National Eye Institute. (2023, November 15). Color blindness. National Institutes of Health. https://www.nei.nih.gov/ learn-about-eye-health/eye-conditions-and-diseases/color-blindness 6. “Swollen eye with conjunctivitis.jpg” by Tanalai at English Wikipedia is licensed under CC BY 3.0 7. National Eye Institute. (2019, July 8). Causes of pink eye. National Institutes of Health. https://www.nei.nih.gov/learn- about-eye-health/eye-conditions-and-diseases/pink-eye/causes-pink-eye 15.5 Diseases and Disorders Related to the Sensory Systems | 849  Figure 15.9 Conjunctivitis Diabetic Retinopathy Diabetic retinopathy (ret-ĭn-OP-ă-thē) is a complication caused by diabetes mellitus. Fluid leakage from blood vessels causes the retinal tissue to swell, resulting in cloudy or blurred vision. If left untreated, diabetic retinopathy can cause blindness. There are various treatments for diabetic retinopathy, such as laser surgery to seal leaking blood vessels or the injection of medications into the eye to decrease inflammation. People with advanced cases of diabetic retinopathy may require surgery to remove and replace the gel-like fluid in the back of the eye, called the vitreous humor. Surgery may also be needed to repair a retinal detachment, a separation of the light-receiving 8 lining in the back of the eye. Glaucoma Glaucoma (glaw-KŌ-mă) is a disease that causes vision loss due to increased pressure inside the eye damaging the optic nerve. Treatment includes prescription eye drops to lower the pressure inside the eye and slow the progression of the disease. If not treated appropriately, glaucoma can cause 8. American Optometric Association. (n.d.). Diabetic retinopathy. https://www.aoa.org/healthy-eyes/eye-and-vision- conditions/diabetic-retinopathy?sso=y 850 | 15.5 Diseases and Disorders Related to the Sensory Systems  blindness. Symptoms of glaucoma include gradual loss of peripheral vision. 9 10 See Figure 15.10 for a simulated image of a person’s vision with glaucoma. Figure 15.10 Simulated Vision With Glaucoma Macular Degeneration Age-related macular degeneration (MĂK-yŭ-lăr Dĕ-gĕn-ĕ-RĀ-shŭn) is a common condition that causes blurred central vision. It is the leading cause 11 of vision loss for people 50 and older. See Figure 15.11 for a simulated image of a person’s vision who has macular degeneration. There are two types of macular degeneration: dry (nonexudative) and wet (exudative). During dry macular degeneration, cellular debris called drusen accumulates and scars the retina. In the wet (exudative) form, which is more severe, blood vessels grow behind the retina and leak exudate fluid, causing hemorrhaging and scarring. There is no treatment for dry macular degeneration, but laser 12 therapy can be used to help treat wet (exudative) macular degeneration. 9. “Eye disease simulation, glaucoma.jpg” by National Eye Institute, National Institutes of Health is in the Public Domain. 10. National Eye Institute. (2023, November 15). Glaucoma. National Institutes of Health. https://www.nei.nih.gov/learn- about-eye-health/eye-conditions-and-diseases/glaucoma 11. “Eye disease simulation, age-related macular degeneration.jpg” by National Eye Institute, National Institutes of Health is in the Public Domain. 12. National Eye Institute. (2021, June 22). Age-related macular degeneration. National Institutes of Health. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/age-related-macular-degeneration 15.5 Diseases and Disorders Related to the Sensory Systems | 851  Figure 15.11 Simulated Vision With Macular Degeneration Myopia Myopia (mī-Ō-pē-ă), also known as nearsightedness, means normal near vision but far-away objects appear blurry. Myopia occurs when the eyeball grows too long from front to back or when there are problems with the shape of the cornea or the lens. These problems make light focus in front of the 13 retina, instead of on it, causing blurriness. See Figure 15.12 for a simulated image of a person’s vision who has myopia. Nearsightedness usually becomes apparent between ages 6 and 14. It is corrected with glasses, contacts, or 14 LASIK surgery. Figure 15.12 Simulated Vision With Myopia 13. “Eye disease simulation, myopia.jpg” by National Eye Institute, National Institutes of Health is in the Public Domain. 14. National Eye Institute. (2020, August 28). Types of refractive errors. National Institutes of Health. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/refractive-errors/types-refractive- errors#section-id-6802 852 | 15.5 Diseases and Disorders Related to the Sensory Systems  Night Blindness (Nyctalopia) Nyctalopia (nik-ta-LŌ-pē-ă) refers to poor vision at night or in dim light. It is also associated with an inability to quickly adapt from a well-illuminated to a poorly illuminated environment. Nyctalopia is not a disease in itself, but rather 15 a symptom of an underlying eye problem, usually a retinal problem. Nystagmus Nystagmus (nĭs-TĂG-mŭs) is a disorder that causes involuntary, rhythmic eye movements. Most nystagmus disorders are caused by an underlying medical condition. The repetitive movements can make it impossible for someone to keep their eyes fixed and focused on any given object. Individuals can be born with congenital nystagmus, or it can occur as a result of another condition or 16 a side effect of medication. Hyperopia and Presbyopia Hyperopia (hī-pĕr-Ō-pē-ă) refers to impaired near vision, commonly referred to as “farsightedness” because distance vision is normal but near vision is impaired. When it occurs in middle-aged and older adults, it is referred to as presbyopia (prez-bī-Ō-pē-ă). As people age, the lens in the eye gets harder and less flexible and stops focusing light correctly on the retina. Presbyopia 17 18 can be corrected with glasses and/or contacts. See Figure 15.13 for a simulated image of a person’s vision who has presbyopia. 15. Cleveland Clinic. (2020, December 1). Night blindness (nyctalopia). https://my.clevelandclinic.org/health/symptoms/ 10118-night-blindness-nyctalopia 16. All About Vision. (2019, March 4). Nystagmus. https://www.allaboutvision.com/conditions/nystagmus.htm 17. National Eye Institute. (2020, August 28). Types of refractive errors. National Institutes of Health. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/refractive-errors/types-refractive- errors#section-id-6802 18. “Pesto ingredients - blurred.jpg” by Colin is licensed under CC BY-SA 4.0 15.5 Diseases and Disorders Related to the Sensory Systems | 853  Figure 15.13 Presbyopia Retinal Detachment Retinal detachment occurs when the retina is pulled away or separated from its normal position. Sudden flashing lights, floaters, and the appearance of a dark shadow in the center of one’s vision are symptoms of a retinal tear. A retinal tear is a medical emergency because it can lead to a retinal detachment. If left untreated, retinal detachment can lead to blindness. Ophthalmologists repair the retinal detachment using laser surgery, freezing treatment, and/or other types of surgery to fix the retinal tear and reattach 19 the retina to the back of the eye. Strabismus Usually, the eyes move together as a pair, but with strabismus (stră-BĬZ-mŭs), the eyes don’t move together in coordination. One eye might drift in, out, up, or down. If not managed, amblyopia can develop. Amblyopia (am-blē-Ō-pē- ă), commonly known as lazy eye, develops when there is a breakdown in how the brain and the eye work together. Over time, the brain relies more and 20 more on the other, stronger eye, while vision in the weaker eye gets worse. 19. National Eye Institute. (2023, November 15). Retinal detachment. National Institutes of Health. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/retinal-detachment 20. National Eye Institute. (2022, September 22). Amblyopia (lazy eye). National Institutes of Health. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/amblyopia-lazy-eye 854 | 15.5 Diseases and Disorders Related to the Sensory Systems  Stye A stye (stī) is a bacterial infection of an oil gland of the eyelid, causing a red, 21 tender bump. See Figure 15.14 for an image of a stye. Treatment includes 22 applying warm compresses to the eyelid and prescription eyedrops. Figure 15.14 Stye EAR DISEASES AND DISORDERS Hearing Loss Hearing loss is classified as conductive hearing loss or sensorineural hearing loss. Conductive hearing loss (kŏn-DUC-tĭv HĒR-ing LŎS) occurs when something in the external or middle ear is obstructing the transmission of sound. For example, cerumen impaction or a perforated tympanic membrane can cause conductive hearing loss. Sensorineural hearing loss (sĕn-sō-rē- NOOR-ăl HĒR-ing LŎS) is caused by pathology of the inner ear, nerve 21. “External hordeolum.jpg” by Inrankabirhossain is licensed under CC BY-SA 4.0 22. National Eye Institute. (2023, November 15). Blepharitis. National Institutes of Health. https://www.nei.nih.gov/learn- about-eye-health/eye-conditions-and-diseases/blepharitis 15.5 Diseases and Disorders Related to the Sensory Systems | 855  damage, or damage to the auditory areas of the brain. Presbycusis (prĕz-bī- KŪ-sĭs) is sensorineural hearing loss that occurs with aging due to gradual 23 nerve degeneration. Cerumen Impaction Cerumen impaction (sĕ-ROO-mĕn Im-PĂK-shŭn) is earwax buildup that blocks the ear canal and can cause symptoms of hearing loss. See Figure 15.15 24 for an image of cerumen impaction. Cerumen can be removed via irrigation 25 of the ear canal, ear drops to dissolve the wax, or manual removal. See Figure 15.15 for an image of an ear irrigation procedure, commonly performed by 26 nurses in a clinic setting. Figure 15.15 Cerumen Impaction 23. This work is a derivative of Open RN Nursing Skills 2e and is licensed by CC BY 4.0 24. “Ear Wax.JPG” by Anand2202 is licensed under CC BY-SA 4.0 25. This work is a derivative of StatPearls by Mankowski & Raggio and is licensed under CC BY 4.0 26. “150915-F-GO352-025.jpg” by Staff Sgt. Jason Huddleston for U.S. Air Force is licensed under CC0. Access for free at https://www.59mdw.af.mil/News/Article-Display/Article/647342/photo-essay-559th-medical-group-at-a-glance/ 856 | 15.5 Diseases and Disorders Related to the Sensory Systems  Figure 15.16 Ear Irrigation Procedure Otitis Externa Otitis externa (ō-TĪ-tĭs eks-TUR-nă) is an external ear inflammation and/or 27 infection. See Figure 15.17 for an image of otitis externa. It is also known as “swimmer’s ear” because it commonly occurs in swimmers due to the continuous exposure to water that washes away the protective wax in their ear canals. Otitis externa causes a reddened and swollen ear canal with associated yellow, white, or grey debris. Patients often report itching in the ear canal with pain that is worsened by pulling upwards and outwards on the auricle. Otitis externa is treated with antibiotic drops placed in the affected 28 ear canal. 27. “Otitis externa.gif” by S. Bhjimji MD is licensed under CC BY 4.0. Access for free at https://www.ncbi.nlm.nih.gov/ books/NBK556055/ 28. This work is a derivative of StatPearls by Medina-Blasini & Sharman and is licensed under CC BY 4.0 15.5 Diseases and Disorders Related to the Sensory Systems | 857  Figure 15.17 Otitis Externa Otitis Media Otitis media (ō-TĪ-tĭs MĒ-dē-ă) refers to a middle ear infection. Ear infections are common in children between the ages of 6 months and 2 years because of the size and shape of their Eustachian tubes. Acute otitis media typically occurs after an upper respiratory infection when the Eustachian tube becomes inflamed and the middle ear fills with fluid, causing ear pain and irritability. This fluid can become infected, causing purulent fluid and low- grade fever. Otitis media is diagnosed by a health care provider using an otoscope (Ō-tō-skōp) to examine the tympanic membrane for bulging and purulent fluid. If not treated, acute otitis media can potentially cause perforation of the tympanic membrane. Treating early acute otitis media with antibiotics is controversial in the United States due to the effort to prevent antibiotic resistance. However, the treatment goals are to control pain and 29 treat infection with antibiotics if a bacterial infection is present. Some children develop recurrent ear infections that cause intermittent hearing loss affecting their language development. For children experiencing 29. This work is a derivative of StatPearls by Danishyar & Ashurst and is licensed under CC BY 4.0 858 | 15.5 Diseases and Disorders Related to the Sensory Systems  recurring infections, a surgery called myringotomy (mĭr-ĭn-GŎT-ō-mē) is performed by an otolaryngologist. During myringotomy surgery, a tympanostomy tube is placed in the tympanic membrane to drain fluid from 30 31 the middle ear and prevent infection from developing. See Figure 15.18 for an image of a tympanostomy tube in the ear. Figure 15.18 Tympanostomy Tube Otosclerosis Otosclerosis (ō-tō-sklĕ-RŌ-sĭs) is abnormal bone formation of the middle ear that can cause hearing loss. Treatment for mild otosclerosis is use of a hearing 30. This work is a derivative of StatPearls by Danishyar & Ashurst and is licensed under CC BY 4.0 31. “Ear Tube.png” by BruceBlaus is licensed under CC BY-SA 4.0 15.5 Diseases and Disorders Related to the Sensory Systems | 859  aid, while more severe otosclerosis is treated with surgery called 32 stapedectomy (stā-pĕ-DEK-tŏ-mē). Presbycusis Presbycusis (prez-bĭ-KŪ-sĭs) refers to hearing impairment that occurs with aging. One in three people in the U.S. between the ages of 65 and 74 has hearing loss, and nearly half of those older than 75 have difficulty hearing. Having trouble hearing can make it hard to understand and follow a doctor’s advice; respond to warnings; and hear phones, doorbells, and smoke alarms. As we age, changes in the inner ear, middle ear, and nerve pathways from the ear to the brain are common. Long-term exposure to noise and some medical conditions can also play a role in hearing loss. Recent research suggests that certain genes make some people more susceptible to hearing loss as they 33 age. Hearing loss may be treated with hearing aids or cochlear implants. Tinnitus Tinnitus (tĭ-NĪ-tŭs) is a ringing, buzzing, roaring, hissing, or whistling sound in the ears. The noise may be intermittent or continuous. Tinnitus can be caused by cerumen impaction, noise trauma, or ototoxic medications, such as diuretics or high doses of aspirin. Military personnel have a high incidence of tinnitus due to noise trauma from loud explosions and gunfire. There are no medications to treat tinnitus, but patients can be referred to an 34 otolaryngologist for treatment such as cognitive therapy or noise masking. Vertigo Vertigo (VUR-tĭ-gō) is a type of dizziness that is often described by patients as, “the room feels as if it is spinning.” Benign positional vertigo (BPV) is a common condition caused by crystals becoming lodged in the semicircular 32. National Institute on Deafness and Other Communication Disorders. (2022, March 16). Otosclerosis. National Institutes of Health. https://www.nidcd.nih.gov/health/otosclerosis 33. National Institute on Deafness and Other Disorders. (2023, March 17). Age-related hearing loss (presbycusis). National Institutes of Health. https://www.nidcd.nih.gov/health/age-related-hearing-loss 34. This work is a derivative of StatPearls by Grossan & Peterson and is licensed under CC BY 4.0 860 | 15.5 Diseases and Disorders Related to the Sensory Systems  canals in the vestibule of the inner ear that send false signals of movement to the brain. BPV can be treated by trained professionals using a specific set of maneuvers that guide the crystals back to the chamber where they are 35 supposed to be in the inner ear. OLFACTORY DISORDERS Anosmia Trauma to the face and certain medications can damage the olfactory nerve and cause the loss of smell, known as anosmia (a-NOZ-mē-ă). There are also temporary causes of anosmia, such as the inflammatory response related to upper respiratory infections or allergies. The sense of smell is important because it is often the first warning signal alerting us to the smoke of a fire, spoiled food, or the odor of a natural gas leak or dangerous fumes. Anosmia can also result in the loss of taste. A person with an impaired sense of taste may require additional spice and seasonings on their food, and in severe 36 cases, cause the loss of their desire to eat. 35. Woodhouse, S., & Doriangricchia, J. P. (2022, November). Benign paraoxysmal positional vertigo (BPPV). Vestibular Disorders Association. https://vestibular.org/article/diagnosis-treatment/types-of-vestibular-disorders/benign- paroxysmal-positional-vertigo-bppv/ 36. National Institute on Deafness and Other Communication Disorders. (2023, July 31). Smell disorders. National Institutes of Health. https://www.nidcd.nih.gov/health/smell-disorders 15.5 Diseases and Disorders Related to the Sensory Systems | 861 862 | 15.5 Diseases and Disorders Related to the Sensory Systems  15.6 Medical Specialties, Diagnostic Testing, and Procedures Related to the Sensory System MEDICAL SPECIALISTS Several medical specialists help diagnose and treat conditions related to the eye. An ophthalmologist (ŏp-thăl-MŎL-ō-jĭst) is a physician who specializes in treating eye diseases and performs eye surgery. An optometrist (ŏp-TŎM-ĕ- trĭst) is a doctor who has received a Doctor of Optometry (op-TOM-ĕ-trē) degree. Optometrists perform eye exams and vision tests and prescribe corrective lenses. Opticians (ŏp-TĬSH-ănz) are technicians trained to design, verify, and fit eyeglass lenses and frames, contact lenses, and other devices to correct eyesight. They use prescriptions supplied by ophthalmologists or optometrists, but do not test vision or write prescriptions for visual 1 correction. Read additional information on the American Association for 1. American Association for Pediatric Ophthalmology and Strabismus (2019, February 26). Difference between an ophthalmologist, optometrist, and optician. https://aapos.org/glossary/difference-between-an-ophthalmologist- optometrist-and-optician 15.6 Medical Specialties, Diagnostic Testing, and Procedures Related to the Sensory System | 863  Pediatric Ophthalmology and Strabismus: Difference Between An Ophthalmologist, Optometrist, and Optician web page. Audiology (od-ē-OL-ŏ-jē) is the study of hearing. Audiologists (od-ē-OL-ŏ- jĭstz) are specialists who study and treat hearing. They perform diagnostic testing like audiometry and provide hearing loss interventions, such as hearing aids. Otology (ō-TŎL-ō-jē) refers to the study of the ear. An otolaryngologist (ō-tō-RĪ-nō-lăr-ĭn-GŎL-ō-jĭst) is a physician who specializes 2 in ear, nose, and throat (ENT) treatments and conditions. Read additional information about audiologists on the American Academy of Audiology’s What is An Audiologist? web page. Ophthalmic Medical Assistant Ophthalmic medical assistants work in ophthalmology and optometry practices and in retail optical settings. Ophthalmic assistants perform prescreening and specialty testing, assist with dispensing glasses and contact lenses, and perform office management duties, including maintaining patient information and billing and insurance processes. Optometric Technician Optometric technicians work under the supervision of an optometrist or 2. Johns Hopkins Medicine. (n.d.). Hearing loss. https://www.hopkinsmedicine.org/health/conditions-and-diseases/ hearing-loss 864 | 15.6 Medical Specialties, Diagnostic Testing, and Procedures Related to the Sensory System  ophthalmologist. Optometric technicians assist an optometrist during eye exams and other optometric procedures. DIAGNOSTIC TESTING Eye Exams Common tools used to screen individuals for vision problems are the Snellen chart, a near vision chart, and Ishihara plates. If a vision problem is identified, the patient is referred to an optometrist for further vision testing. An ophthalmoscope (op-THAL-mŏ-skōp) is an instrument used to view the eye, and ophthalmoscopy (op-thal-MOS-kŏ-pē) is the process of viewing the eye. Snellen Chart 3 Distant vision is tested by using the Snellen chart. See Figure 15.19 for an image of the Snellen chart. The patient is placed 20 feet away from the chart and asked to cover one eye and read the letters from the lowest line they can see clearly. This is repeated with the other eye. A person with normal visual acuity (VIZH-u-ăl ă-KŪ-ĭt-ē) or sharpness or clearness of vision is documented as having 20/20 vision. A person with impaired vision has a different lower denominator of this fraction. For example, a vision measurement of 20/30 indicates that the patient has decreased distant vision and can see letters 4 clearly at 20 feet that a person with normal vision can see clearly at 30 feet. 3. “Snellen chart.jpg” by Jeff Dahl is licensed under CC BY-SA 3.0 4. Sue, S. (2007). Test distance vision by using a Snellen chart. Community Eye Health, 20(63), 52. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2040251/ 15.6 Medical Specialties, Diagnostic Testing, and Procedures Related to the Sensory System | 865  Figure 15.19 Snellen Chart Near Vision Chart Near vision is assessed by having a patient read from a prepared card that is 5 held 14 inches away from the eyes. See Figure 15.20 for an image of a prepared card used to assess near vision. 5. “111012-F-ZT401-067.JPG” by Airman 1st Class Brooke P. Beers for U.S. Air Force is in the Public Domain. Access for free at https://www.pacaf.af.mil/News/Article-Display/Article/593609/keeping-sight-all-right/ 866 | 15.6 Medical Specialties, Diagnostic Testing, and Procedures Related to the Sensory System  Figure 15.20 Near Vision Card Ishihara Plates Ishihara plates are commonly used to assess color vision. Each of the colored 6 dotted plates shows either a number or a path. See Figure 15.21 for an example of Ishihara plates. A person with color blindness is not able to distinguish the numbers or paths from the other colored dots on the plate. Figure 15.21 Ishihara Plates 6. This work is a derivative of “Ishihara 9.png” and "Ishihara_1.png" by Shinobu Ishihara and in the Public Domain. 15.6 Medical Specialties, Diagnostic Testing, and Procedures Related to the Sensory System | 867  Ear Exams An otoscope (Ō-tō-skōp) is an instrument used to view the ear, and otoscopy (ō-TŎS-kō-pē) is the process of viewing the ear. Audiometry Audiometry (od-ē-OM-ĕ-trē) refers to diagnostic testing that measures hearing. This includes tests of mechanical sound transmission (middle ear function), neural sound transmission (cochlear function), and speech discrimination ability (central integration). A complete evaluation of a patient’s hearing is done by trained personnel using instruments designed specifically for this purpose. For example, an audiometer (od-ē-OM-ĕt-ĕr) is an electric instrument consisting of a tone generator, a bone conduction oscillator for measuring cochlear function, and earphones for air conduction testing. Sounds are played through headphones to one ear at a time, and the patient is asked to respond if they hear each sound. An audiogram (OD-ē-ō- gram) is a chart that shows the results of a hearing test. It shows how well sounds are heard in terms of frequency (high-pitched sounds versus low- 7 pitched sounds) and intensity (loudness). 7. Johns Hopkins Medicine. (n.d.). Hearing loss. https://www.hopkinsmedicine.org/health/conditions-and-diseases/ hearing-loss 868 | 15.6 Medical Specialties, Diagnostic Testing, and Procedures Related to the Sensory System 15.7 Sensory System Learning Activities Interactive Learning Activity: Practice labeling the parts of the eye, Activity 1. An interactive H5P element has been excluded from this version of the text. You can view it online here: https://wtcs.pressbooks.pub/medterm/?p=401#h5p-66 Interactive Learning Activity: Practice labeling the parts of the eye, Activity 2. An interactive H5P element has been excluded from this version of the text. You can view it online here: https://wtcs.pressbooks.pub/medterm/?p=401#h5p-69 Interactive Learning Activity: Practice labeling the parts of the ear. An interactive H5P element has been excluded from this version of the text. You can view it online here: https://wtcs.pressbooks.pub/medterm/?p=401#h5p-64 Interactive Learning Activity: Study sensory system medical terms discussed in this chapter using these 15.7 Sensory System Learning Activities | 869  flashcards. An interactive H5P element has been excluded from this version of the text. You can view it online here: https://wtcs.pressbooks.pub/medterm/?p=401#h5p-191 Interactive Learning Activity: Check your knowledge of sensory system terminology. An interactive H5P element has been excluded from this version of the text. You can view it online here: https://wtcs.pressbooks.pub/medterm/?p=401#h5p-74 Interactive Learning Activity: Using the sample documentation provided, drag the terms on the right to their appropriate spaces within the documentation. An interactive H5P element has been excluded from this version of the text. You can view it online here: https://wtcs.pressbooks.pub/medterm/?p=401#h5p-71 Interactive Learning Activity: Using the sample documentation provided, drag the terms on the right to their appropriate spaces within the documentation. An interactive H5P element has been excluded from this version of the text. You can view it 870 | 15.7 Sensory System Learning Activities online here: https://wtcs.pressbooks.pub/medterm/?p=401#h5p-72 Interactive Learning Activity: Practice identifying and defining word parts for terms discussed in this chapter. An interactive H5P element has been excluded from this version of the text. You can view it online here: https://wtcs.pressbooks.pub/medterm/?p=401#h5p-210 You can also print this as a Chapter 15 Practice Worksheet and check your answers with this Answer Key PDF. 15.7 Sensory System Learning Activities | 871 15.8 Glossary Amblyopia (am-blē-Ō-pē-ă): Often called “lazy eye,” a vision development disorder where an eye fails to achieve normal visual acuity. (Chapter 15.5) Anosmia (a-NŌZ-mē-ă): Loss or impairment of the sense of smell, which can be temporary or permanent. (Chapter 15.5) Astigmatism (ă-STIG-mă-tizm): A vision condition that causes blurred vision due to the irregular curvature of the cornea or lens. (Chapter 15.5) Audiogram (AW-dē-ō-gram): A graphic record of the results of a hearing test, typically showing hearing sensitivity at different frequencies. (Chapter 15.6) Audiologists (aw-dē-OL-ŏ-jĭsts): Health care professionals specializing in diagnosing, managing, and treating hearing or balance problems. (Chapter 15.6) Audiology (aw-dē-OL-ŏ-jē): The study of hearing. (Chapter 15.6) Audiometer (aw-dē-OM-ĕt-ĕr): An electronic device used in audiometry to generate pure tones of controlled intensity for hearing testing. (Chapter 15.6) Audiometry (aw-dē-OM-ĕ-trē): The testing of a person’s hearing ability, usually by producing sounds of different frequencies and intensities. (Chapter 15.6) Auricle (AW-rĭ-kl): The large fleshy structure on the lateral aspect of the head, directing sound waves into the ear canal. (Chapter 15.4) Cataract (KAT-ă-rakt): A progressive disease of the lens causing cloudiness and lack of transparency, leading to vision impairment. (Chapter 15.5) Cerumen impaction (sĕ-ROO-mĕn Im-PĂK-shŭn): The buildup of earwax (cerumen) in the ear canal, which can lead to symptoms such as hearing loss, tinnitus, or discomfort. (Chapter 15.5) Cochlea (KŎK-lē-ă): A part of the inner ear involved in hearing; it converts sound waves into neural signals. (Chapter 15.4) Conductive hearing loss (kŏn-DUC-tĭv HĒR-ing LŎS): Hearing loss caused by problems with the ear canal, eardrum, or middle ear and its little bones (the malleus, incus, and stapes). (Chapter 15.5) 872 | 15.8 Glossary  Conjunctiva (kŏn-jŭnk-TI-va): The inner surface of each lid, a thin membrane that extends over the white areas of the eye called the sclera, connecting the eyelids to the eyeball. (Chapter 15.4) Conjunctivitis (kŏn-jŭnk-tĭ-VĪT-ĭs): An infection or inflammation of the conjunctiva, causing redness, swelling, and often discharge in the eye. (Chapter 15.5) Cornea (KOR-nē-ă): The transparent front part of the eye covering the iris, pupil, and anterior chamber, playing a key role in focusing vision. (Chapter 15.4) Diabetic retinopathy (ret-ĭn-OP-ă-thē): A complication of diabetes mellitus causing fluid leakage from blood vessels in the retina, leading to vision impairment. (Chapter 15.5) Eustachian tube (yōō-STĀ-shən tūb): A tube connecting the middle ear to the pharynx, helping equalize air pressure across the tympanic membrane. (Chapter 15.4) Glaucoma (glăw-KŌ-mă): A group of eye conditions that damage the optic nerve, often caused by abnormally high pressure in the eye. (Chapter 15.5) Hyperopia (hī-pĕr-Ō-pē-ă): Also known as farsightedness, a condition where distant objects can be seen more clearly than close ones. (Chapter 15.5) Incus (ĬN-kŭs): A small anvil-shaped bone in the middle ear, connecting the malleus to the stapes. (Chapter 15.4) Inner ear (IN-er ĒR): The part of the ear that includes the cochlea, vestibule, and semicircular canals, responsible for processing sound and maintaining balance. (Chapter 15.4) Iris (IR-ĭs): The colored part of the eye, a smooth muscle that controls the diameter and size of the pupil. (Chapter 15.4) Lacrimal gland (LAK-rĭ-măl glănd): A gland located beneath the lateral edges of the nose that produces tears. (Chapter 15.4) Legal blindness (LĒ-găl BLĪND-nĕss): A defined level of visual impairment that has been established as a threshold for eligibility for governmental disability benefits; typically, visual acuity of 20/200 or less in the best- corrected eye. (Chapter 15.5) Low vision (LŌ VIZH-ŭn): A condition where an individual has significant visual impairment that cannot be fully corrected with standard glasses, 15.8 Glossary | 873 contact lenses, medicine, or surgery, and which interferes with daily activities. (Chapter 15.5) Macular degeneration (MĂK-yŭ-lăr Dĕ-gĕn-ĕ-RĀ-shŭn): A common eye condition among older adults that leads to loss of vision in the center of the visual field (the macula) due to damage to the retina. (Chapter 15.5) Malleus (MĂL-ē-ŭs): A small bone in the middle ear attached to the tympanic membrane, resembling a hammer. (Chapter 15.4) Myopia (mī-Ō-pē-ă): Also known as nearsightedness, a common vision condition where distant objects appear blurry. (Chapter 15.5) Myringotomy (mĭr-ĭn-GŎT-ō-mē): A surgical procedure where a small incision is made in the eardrum to relieve pressure or drain fluid. (Chapter 15.5) Nyctalopia (nik-ta-LŌ-pē-ă): Poor vision at night or in dimly lit environments, commonly known as night blindness. (Chapter 15.5) Nystagmus (nĭs-TĂG-mŭs): Involuntary rhythmic movement of the eyes, which can impair vision and affect balance. (Chapter 15.5) Ophthalmologist (ŏp-thăl-MŎL-ō-jĭst): A physician who specializes in diagnosing and treating eye disorders and performing eye surgery. (Chapter 15.6) Ophthalmoscope (op-THAL-mŏ-skōp): An instrument used to examine the interior structures of the eye. (Chapter 15.6) Ophthalmoscopy (op-thal-MOS-kŏ-pē): The examination of the interior of the eye, particularly the retina, using an ophthalmoscope. (Chapter 15.6) Optic nerve (OP-tik nerv): The nerve that transmits visual information from the retina to the brain. (Chapter 15.4) Opticians (ŏp-TĬSH-ăns): Technicians who design, verify, and fit eyeglass lenses and frames, contact lenses, and other devices to correct eyesight. (Chapter 15.6) Optometrist (ŏp-TŎM-ĕ-trĭst): A health care professional who examines eyes for vision and health problems and prescribes corrective lenses. (Chapter 15.6) Otitis externa (ō-TĪ-tĭs eks-TUR-nă): Inflammation or infection of the outer ear canal, often referred to as “swimmer’s ear.” (Chapter 15.5) Otitis media (ō-TĪ-tĭs MĒ-dē-ă): Inflammation or infection of the middle ear, 874 | 15.8 Glossary common in children and often associated with upper respiratory infections. (Chapter 15.5) Otolaryngologist (ō-tō-lăr-ĭn-GŎL-ō-jĭst): A physician who specializing in ear, nose, and throat disorders, also known as an ENT doctor. (Chapter 15.6) Otology (ō-TŎL-ō-jē): The study of the ear and its diseases. (Chapter 15.6) Otosclerosis (ō-tō-sklĕ-RŌ-sĭs): A hearing loss condition caused by abnormal bone growth in the middle ear. (Chapter 15.5) Otoscope (Ō-tō-skōp): An instrument used for visual examination of the ear canal and tympanic membrane. (Chapter 15.5, Chapter 15.6) Otoscopy (ō-TŎS-kō-pē): The examination of the ear canal and eardrum with an otoscope. (Chapter 15.6) Pinna (PĬN-ă): Another term for the auricle, the visible part of the ear that resides outside of the head. (Chapter 15.4) Presbycusis (prez-bĭ-KŪ-sĭs): Age-related hearing loss, often due to gradual nerve degeneration and other changes in the inner ear. (Chapter 15.5) Presbyopia (prez-bī-Ō-pē-ă): An age-related condition in which the ability to focus on close objects decreases over time. (Chapter 15.5) Pupil (PŪ-pĭl): The hole at the center of the eye that allows light to enter, its size is controlled by the iris. (Chapter 15.4) Retina (RĔT-ĭ-nă): The innermost layer of the eye, containing photoreceptors and nerve cells for initial processing of visual stimuli. (Chapter 15.4) Sclera (sklĕr-ă): The white, outer layer of the eyeball that extends from the cornea to the optic nerve at the back of the eye. (Chapter 15.4) Sensorineural hearing loss (sĕn-sō-rē-NOOR-ăl HĒR-ing LŎS): A type of hearing loss resulting from damage to the inner ear (cochlea) or to the nerve pathways from the inner ear to the brain. (Chapter 15.5) Stapedectomy (stā-pĕ-DEK-tŏ-mē): A surgical procedure to remove part or all of the stapes bone and replace it with a prosthesis to improve hearing. (Chapter 15.5) Stapes (STĀ-pēz): A stirrup-shaped bone in the middle ear, attached to the inner ear where sound waves are converted into neural signals. (Chapter 15.4) Strabismus (stră-BĬZ-mŭs): A condition where the eyes do not properly align with each other when looking at an object. (Chapter 15.5) 15.8 Glossary | 875  Stye (STĪ): An infection of an oil gland in the eyelid, leading to a painful, red swelling on the eyelid. (Chapter 15.5) Tinnitus (tĭ-NĪ-tŭs): A condition characterized by hearing ringing, buzzing, or other noises in the ear in the absence of external sound. (Chapter 15.5) Total blindness (TŌ-tăl BLĪND-nĕss): The complete absence of visual perception, characterized by the inability to perceive light or discern any visual images. (Chapter 15.5) Tympanic membrane (tĭm-PĂN-ik MEM-brān): Also known as the eardrum, it vibrates in response to sound waves. (Chapter 15.4) Vertigo (VUR-tĭ-gō): A sensation of spinning or dizziness, often caused by issues with the inner ear or vestibular system. (Chapter 15.4, Chapter 15.5) Vestibule (ves-tĭ-būl): A part of the inner ear that contributes to balance and spatial orientation. (Chapter 15.4) Vestibulocochlear nerve (vĕs-tĭ-būl-ō-KŌ-klē-ăr nerv): The nerve that carries auditory and balance information from the inner ear to the brain. (Chapter 15.4) Visual acuity (VIZH-u-ăl ă-KŪ-ĭt-ē): The sharpness or clearness of vision, typically measured with a Snellen chart. (Chapter 15.5, Chapter 15.6) Visual impairment (VIZH-ŭ-al Im-PĀR-mĕnt): A decrease in the ability to see to a significant degree, which may cause problems not fixable by usual means, such as glasses or medication. (Chapter 15.5) 876 | 15.8 Glossary PART XVI CHAPTER 16 NERVOUS SYSTEM TERMINOLOGY Chapter 16 Nervous System Terminology | 877 878 | Chapter 16 Nervous System Terminology