Download ACTIVITY 5A STUDENT HANDOUT Glossary: Description and

ACTIVITY 5A STUDENT HANDOUT
Glossary: Description and Function of Parts of the Human Ear
EXTERNAL EAR
AURICLE: the ear flap, ear lobe, or outer ear (pinna); collects sound waves and
transmits them through the external acoustic meatus (auditory canal) to the
tympanic membrane.
EXTERNAL AUDIT ORY CANAL:an S-shaped structure about 2 cm in length,
lined with numerous glands secreting a yellow, waxy substance, cerumen.
CERUMEN: yellow, waxy substance; lubricates and protects the ear; “ear wax.”
MIDDLE EAR
TYMPANIC CA VITY middle
:
ear, tiny cavity in the temporal bone; holds the three
auditory ossicles; has five openings (opening covered by the tympanic membrane),
the opening of the auditory tube (eustachian tube) which connects the middle ear
with the nasopharynx and through which outside air can enter; the opening into the
mastoid cavity, the openings in to the inner ear (round and oval windows).
TYMPANIC MEMBRANE: eardrum.
AUDIT ORY OSSICLES: three tiny bones of middle ear, including malleus
(hammer), incus (anvil), and stapes (stirrup).
STAPEDIUS MUSCLE: attached to the stapes.
TENSOR TYMPANI MUSCLE: attached to the handle of the malleus.
EUSTACHIAN TUBE: connects middle ear with mouth to equalize pressure.
The three functions of the Middle Ear
1. TRANSMIT ENERGY from sound vibrations in the air column of the external
auditory meatus across the middle ear into the fluid contained within the
cochlea (central hearing apparatus); bones of middle ear pick up the vibrations
from the tympanic membrane and transmit them across the middle ear to the oval
window (the opening to the inner ear).
2. PROTECTIVE: reduces the amplitude of vibrations accompanying intense
sounds of low frequency; contraction of the tensor tympani and the stapedius
restricts the motion of the chain of ossicles and minimizes shock to the inner ear.
3. EQUALIZE AIR PRESSURE on both sides of the membrane via the auditory
tube to prevent the tympanum from rupturing.
INNER EAR
© 2001 UTHSCSA "Positively Aging®" a trade mark of the University of Texas Health Science Center at San Antonio
6
6-1
UNIT
Consists of bony and membranous labyrinths, composed of a series of canals
hollowed out of the temporal bone, filled with perilymph; membranous labyrinth,
lying entirely within the bony labyrinth, is filled with endolymph.
BONY LABYRINTH: consists of the cochlea, containing the organ of hearing (organ
of Corti), and the vestibule and semicircular canals containing the organs of equilibrium.
MEMBRANOUS LABYRINTH: consists of the cochlear duct within the cochlea, the
utricle and saccule within the vestibule, and the semicircular ducts within the
semicircular canals; those portions of the inner ear concerned with equilibrium are
collectively called the vestibular apparatus.