Chapter 13 Ear A, Tympanic membrane demonstrating acute otitis media (AOM). B, Normal tympanic membrane.

Objective 1: Identify organs and structures of the ear. Chapter 13 Objective 1: Identify organs and structures of the ear.

Function of the Ear Two functions of the ear are to hear and to provide the sense of balance. The ear is made up of three parts: the external ear, the middle ear, and the inner ear, also called the labyrinth. We hear because sound waves vibrate through the ear, where they are transformed into nerve impulses that are then carried to the brain. Can you think of causes of abnormal functioning of the ear?

Anatomy of the Ear What are the functions of the three main parts of the ear? What is cerumen, and where is it found?

Ear external ear auricle (pinna): located on both sides of the head external auditory meatus: short tube that ends at the tympanic membrane The auricle directs sound waves into the external auditory meatus. It is the part of the ear tissue that is pierced for earrings. The external auditory meatus, also called “canal,” has an inner part lying within the temporal bone of the skull and containing the glands that secrete earwax (cerumen).

Ear (cont’d) middle ear tympanic membrane (eardrum): semitransparent membrane that separates the external auditory meatus and the middle ear cavity and transmits sound vibrations to the ossicles eustachian tube: connects the middle ear and the pharynx ossicles: bones of the middle ear that carry sound vibrations The eustachian tube equalizes the air pressure on both sides of the eardrum. Describe the ossicles and their functions. (The ossicles are the malleus (hammer), incus (anvil), and stapes (stirrup). The stapes connects to the oval window, which transmits the sound vibrations to the inner ear.)

The Middle Ear Note the complexity of the elements that make up the middle ear.

Ear (cont’d) labyrinth (inner ear) cochlea: snail-shaped and contains the organ of hearing; connects to the oval window in the middle ear semicircular canals and vestibule: contain receptors and endolymph that help the body maintain its sense of balance mastoid bone and cells: located in the skull bone behind the external auditory meatus The labyrinth includes the bony spaces within the temporal bone of the skull. The semicircular canals and vestibule help regulate equilibrium.

Objective 2: Define and spell word parts related to the ear. Chapter 13 Objective 2: Define and spell word parts related to the ear.

Combining Forms of the Ear audi/o aur/i, aur/o, ot/o cochle/o labyrinth/o mastoid/o myring/o staped/o tympan/o vestibul/o What are the combining forms that mean “ear,” and how might they be used in terminology? What is an audiogram?

Review Question Have students complete Exercise Figure A in their textbooks as you review the slides Answers: ear: aur/i, aur/o, ot/o labyrinth: labyrinth/o stapes: staped/o tympanic membrane: myring/o, tympan/o mastoid bone: mastoid/o Copyright © 2014, 2012, 2009, 2005, 2002, 1998, 1994, 1989, 1985 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved.

Review Question The combining form for eardrum is myring/o staped/o audi/o Answer: a) myring/o (think of Ringo Starr beating the drum) Define the other combining forms.

Helpful Information tympan/o…..middle ear (usually) myring/o…...eardrum (tympanic membrane) labyrinth/o…inner ear Create terms using these combining forms.

Chapter 13 Objective 8: Interpret, read, and comprehend medical language in simulated medical statements, documents, and electronic health records.

Read Medical Terms in Use Acute otitis media is one of the most common pediatric infections. Most middle ear infections are caused by bacteria, and some by viruses. Symptoms include otalgia, otorrhea, ear pulling, and irritability. The tympanic membrane will be bulging, red in color, with a thickened appearance and reduced translucency. Antibiotics may be ordered if the infection does not resolve on its own. If unresponsive to antibiotic treatment, a myringotomy may be performed to identify the causative pathogen, allowing for the appropriate antibiotic treatment to be prescribed. Ask students to define the bolded terms.