Upgrade to remove ads
Only $35.99/year

Review 1 CSD 806

Terms in this set (77)

What are the portions of the ear?
outer, middle, and inner
What is included in the auditory nervous system?
auditory nerve & central auditory pathway
What is included in the peripheral auditory system?
outer ear, middle ear, inner ear, auditory nerve
What type of stimuli does the peripheral auditory system receive?
stimuli from the same side
What is included in the central auditory system?
central auditory pathway
What type of stimuli does the central auditory system receive?
stimuli from both sides
What are two ways of dividing the auditory system?
the structures & types of signals processed (ear & ANS) vs the features of signal processing (peripheral/central auditory system)
What is the main function of the temporal bone in terms of the ear?
protection
What are the five portions of the temporal bone?
mastoid, tympanic, petrous, squamous, zygomatic process
What are the major landmarks of the pinna?
helix, concha, lobule, tragus, antihelix
What is the shape/angle of the pinna?
it protrudes posteriorly and superiorly at a 15-30 degree angle (different for everyone)
What is the internal composition of the pinna structure?
cartilage and tissue
What does cartilage do for the pinna?
creates the shape
Does the pinna have muscles?
Yes, but they are tiny and have lost voluntarily control through evolution
Why is the earlobe softer than the rest of the pinna?
there is only skin, no cartilage/tissue
What is the shape of the outer ear canal?
irregular and tube-like
What are the dimensions of the outer ear canal?
~0.75 cm diameter at the entrance & ~2-3 cm in length
What is the internal structure of the outer ear canal?
covered in skin with a cartilaginous portion and a bony portion
What is the cartilaginous portion of the outer ear canal?
lateral 1/3 of canal, lined with hair, contains ceruminous and sebaceous glands
What do the ceruminous glands and the sebaceous glands do?
create earwax
What is the bony portion of the outer ear canal?
medial 2/3 of canal, contains no hair or glands, contained in temporal bone
What is the isthmus?
narrow portion of the outer ear canal made from tympanic bone that serves as a junction between the outer cartilage and inner bony portion
We should pull the pinna laterally, posteriorly, and superiorly when inspecting the ear canal & tympanic membrane of an ADULT patient. Why?
these directions help to straighten the ear canal from its irregular shape
What is epithelial migration?
process to remove wax from the canal through the death/regrowth of skin cells
Why does a patient with an ear canal infection have increased pain when the pinna is pulled or when the tragus is pushed?
the ear canal is a continuation of the pinna's skin, so the pain from the infection can be felt outside the canal
How does the pinna help protect the auditory system?
reduces vibration to cushion damage to the hair cells
How does the ear canal protect the auditory system?
extends deep to prevent injury, maintain temperature/humidity, and ensure structure safety
What is the purpose of earwax?
protection from foreign bodies, lubricant for the canal, prevents bacteria
How does the pinna aid in localization of a sound source?
modification of the sound spectrum in different patterns as sound comes from different directions (only works well w/ high frequencies)
What is monaural localization?
---
What is sagittal plane localization?
---
Why does the outer ear modify the sound spectrum?
to transition the sounds the ear cannot process into sounds that fall into the correct resonant frequencies for the middle ear
What is the approximate resonant frequency of the concha?
~5-6 kHz
What is the approximate resonant frequency of the ear canal?
~2.5-3.5 kHz
How does the resonant frequency change as the length of an ear canal goes from 3.5 cm to 2.5 cm? Why?
---
Does the resonant frequency of the ear canal change when you conduct audiometry using an insert earphone? Why?
===
What is the frequency range for which the ear canal maximally increases sound amplitude based on its transfer function from some studies? (~range of the resonant frequency of the canal)
---
What are the three portions of the middle ear?
tympanic cavity, eustachian tube, mastoid cavity
What is the tympanic cavity?
air-filled chamber in the tympanic portion of the temporal bone
What are the dimensions of the tympanic cavity?
~2-4 mm wide, ~13 mm tall, ~2 cubic cm volume
What are the three space areas of the tympanic cavity?
epitympanum, mesotympanum, hypotympanum
What is on the lateral wall of the tympanic cavity?
tympanic membrane
What is on the medial wall of the tympanic cavity?
promonotory, oval window, round window niche
What is on the anterior wall of the tympanic cavity?
opening of the eustachian tube, orifice for the tendon of the tensor tympani
What is on the posterior wall of the tympanic cavity?
tympanic aditus, pyramidal eminence
What is on the roof of the tympanic membrane?
tegmen tympani
What is on the floor of the tympanic membrane?
---
What is the shape of the tympanic membrane?
irregular oval with a concave (cone-shaped) apex inward that tilts laterally at the top
What are the dimensions of the tympanic membrane?
~55-85 square mm area, ~9-19 mm tall, ~8-9 mm wide, ~0.1mm thick
What are the important landmarks of the tympanic membrane?
umbo, malleal manubrium, malleal prominence, cone of light
Do the landmarks of the TM mean that some structures develop on its surface? Why?
No. The landmarks are not on the surface, they are behind the TM. They can be seen because of the membrane's opaqueness.
What is the significance of identifying the landmarks of the tympanic membrane?
diagnostics, awareness of abnormalities, shows difference between L & R ears
What are the three layers of the tympanic membrane?
outer skin layer, middle fibrous layer, inner mucous layer
What are the two regions of the tympanic membrane?
pars tensa and pars flacida
What TM layers are included in the pars tensa?
outer, middle, and inner layers
What TM layers are included in the pars flaccida?
outer and inner layers ONLY
What portion of the TM is the pars tensa?
lower 4/5
What portion of the TM is the pars flaccida?
upper 1/5
What is the appearance of the pars tensa?
translucent pearly grey hue
What is the appearance of the pars flaccida?
opaque and skin-like
What are the four quadrants of the TM?
postero-superior, postero-inferior, antero-superior, antero-inferior
What are the three middle ear ossicles?
malleus, incus, stapes
What are the two articulations of the ossicular chain?
incudomalleal, incudostapedial
How does the malleus connect to the tympanic membrane?
ligaments and the tendons of the tensor tympani muscle
How does the stapes connect to the oval window?
connection through annular ligament and stabilization through stapedius muscle
What is the function of the eustachian tube?
pressure equalization on each side of the TM, drainage of fluids
What are the two openings of the eustachian tube?
middle ear and nasopharyngeal
Where is the middle ear opening of the eustachian tube?
anterior wall of the tympanic cavity
Where is the nasopharyngeal opening of the eustachian tube?
lateral wall of the nasopharynx, near the soft palate
What is the natural state of the eustachian tube's openings?
tympanic is always open, nasopharynx is closed
What are the two portions of the eustachian tube and what are their proportions?
tympanic (lateral 1/3), nasopharynx (medial 2/3)
What is the structure of the tympanic portion of the eustachian tube?
bony and relatively wide
What is the structure of the nasopharynx portion of the eustachian tube?
cartilaginous, but the portion near the opening is an incomplete ring of cartilage w/ soft tissue
What is the orientation of the eustachian tube?
courses inferior, medial, and anterior w/ a horizontal 45 degree angle
What is the difference in the eustachian tube between adults and children?
a child's eustachian tube lies flatter than an adults which can lead to problems with drainage and increased cases of otitis media
What are the two muscles that help actively open the eustachian tube?
tensor veli palatini and levator veli palatini
What are the basic features of the mastoid?
series of interconnecting, air-filled cells in the temporal bone
Other sets by this creator