UNIT 7: External Ear and Middle Ear Flashcards
3 transduction/transmission parts of hearing
transduction of sound from acoustical energy to mechanical energy
transduction of mechanical energy into electrochemical energy
transmission and interpretation of electrochemically produced siganl
the ear is a structure that houses the….
vestibulocochlear organs for senses of equilibrium and hearing
3 divisions of ear
external ear
middle ear
inner ear
main function of the external/outer ear
gathering and conducting sound to tympanic membrane
external outer ear includes
auricle and concha
external auditory meatus
lower animals have an advantage w their external ear
can control position of auricles to capture sound using auricular muscles (innervated by CN VII)
Most visible part of hearing apparatus
auricle/pinna
auricle/pinna are made of…. and attached to the ….
flexible, thin elastic cartilage core = auricular cartilage
attached to skull around opening of external auditory meatus by muscles and ligaments
cartilaginous core of pinna is continuous w ______
cartilaginous portion of EA
structures of auricle/pinna are constant despite…
genetic variation in shape and size
auricle/pinna reaches adult size by
9-12 years
external auditory meatus is ____ in length, from ____ to _____, roughly ____ shaped in path
2.5 cm
concha to tympanic membrane
S shaped
external auditory meatus’s lateral 1/3 is _____ and medial 2/3 is ____
cartilaginous
bony
bony portion of EAM diameter is slightly ____ then cartilaginous portion, _____ end is sloped, EAM has its own _____ characteristics
less then cartilaginous portion
medial
resonant
EAM’s bony portion has a narrow concentric groove called
tympanic sulcus
tympanic membrane is a ____ and ____ membrane, ___mm in diameter - separates the ___ from _____
thin and oval
10 mm
external ear from tympanic cavity
differences in lengths of roof and floor of EAM put the TM in an _______
oblique position
angle formed bw TM and floor of the EAM is about 55’
under the light the tympanic membrane has a
glistening pearly grey appearance
bc of the TM’s concavity and oblique orientation the anterior/inferior quadrant…
glows brightly and is called the cone of light
TM is _____, w its center point called the ____
concave
umbo
TM is semitransparent - the outline of the _____
handle of malleus (attached to medial surface) can be seen extending upwards and forwards
two regions of the TM are
pars flaccida and pars tensa
malleolar fold in the TM is
created by ligament attaching lateral process of malleus to TM
the TM is attached to the tympanic sulcus of the EAM by
a fibrous ring = annular ligament - aka a circular ring of CT …. annular meaning it runs all the way around
annular ligament has ____ CT in the region of the pars flaccida and ____ CT in region of the pars tensa
sparse CT
fibrous CT
TM is a trilaminar membrane, its 3 layers are
lateral surface = continuous w skin of EAM
middle layer = core of fibrous CT
inner (medial) layer = continuous w mucosa of TM