Chapter 6 Flashcards
Consists of the outer, middle, and inner ear
Peripheral system
Consists of the outer and middle ear
Conductive system
Consists of the inner ear
Sensory system
System that uses the central mechanism (electrochemical energy)
Central system
Area of the ear that uses acoustic energy
Outer ear
Area of the ear that uses mechanical energy
Middle ear
Area of the ear that uses hydrodynamic energy
Inner ear
Area of the ear that uses electrical energy
Beyond the inner ear
Collects sound from the environment, most noticeable part, funnel like configuration
Auricle/pinna
What is the auricle/ pinna made of?
Cartilage
Helps funnel sound into external auditory canal.
Important for the localization of sound.
Concha
Effective for blocking sounds.
Tragus
More efficient at delivering high frequency sounds than low frequency sounds.
Pinna
Extends from concha to eardrum and is 2.6cm or about 1 inch in length and 5-7mm in diameter.
External acoustic meatus/ EAC
Outer portion passes through cartilage
Inner portion passes through the temporal bone
Cartilaginous EAC
Inner portion passes through the temporal bone
Bony external EAC
produce oily, fatty substance
Sebaceous gland
How does earwax (cerumen) exit the ear?
distorted through chewing or speaking.
keep foreign objects from passing into the inner part
Cerumen
Part of the EAC that has no glands and no hair
Bony EAC
marks border between outer and middle ear; extremely thin and efficient vibrating system, rich in blood supply
Tympanic membrane
What are the 3 layers of the tympanic membrane?
Epidermal, fibrocartilaginous, mucosal
viewed from the EAC & made up of the same skin
Outer epidermal layer
a layer of tough, fibrous, connective tissue; contributes to the membrane’s ability to vibrate with impinging sound waves
Middle fibrocartilaginous layer
- viewed from the middle-ear space - completely lined with mucous membrane
Mucosal layer
Oval air filled space; Separated from the ear canal by the tympanic membrane
Middle ear
What is the middle ear connected to?
nasopharynx (nose and throat) through the Eustachian tube.
The eustachian tube is usually kept ____
Closed
When is the eustachian tube open?
yawning, sneezing, swallowing, or when excessive pressure is applied from nose.
What are the 3 functions of the eustachian tube?
- Equalize air pressure on both sides of tympanic membrane
- Provides air supply essential to the metabolism of middle ear tissue
- Drainage of middle ear secretions into the nasopharynx
bony portion of the inner ear extended into the middle ear space
Separates two connections between the middle and inner ear
Promontory
What are the 3 bones of the middle ear?
Malleus, incus, stapes
Must OVERCOME the loss of energy (25~30dB) that results when sound passes from one medium (air) to another medium (fluid).
Middle ear impedance matcher
What are the mechanisms of middle ear impedance matching
- Areal ratio of the tympanic membrane to the stapes footplate
- Lever action of the ossicles
Pulls the stapes laterally and posteriorly, making the movement of the ossicular chain less efficient - Ear protection
Stapedius muscle
What does the stapedius muscle help to improve?
improve word recognition in noise
pulls manubrium medially; protects ear from loud sound
tensor tympani muscle
