PART 2: THE EAR: HEARING AND BALANCE Flashcards
move fluid to stimulate hearing receptors, whereas gross movements of the head disturb fluids surrounding the balance organs.
sound vibrations
Receptors that respond to such physical forces are called
mechanoreceptors
is composed of the auricle and the external acoustic meatus.
The external ear, or outer ear
shell-shaped structure surrounding the auditory canal opening.
The auricle, or pinna
is a short, narrow chamber carved into the temporal bone of the skull
The external acoustic meatus (or auditory
canal)
skin-lined walls, which secrete waxy yellow cerumen, or earwax
ceruminous glands
provides a sticky trap for foreign bodies and
repels insects.
cerumen, or earwax
Sound waves entering the auditory canal eventually hit the (which separates the external from the middle ear.)
tympanic membrane or eardrum
is a small, air-filled, mucosa-lined cavity within the temporal bone. It is flanked laterally by the eardrum and medially by a bony wall with two openings, the oval window and the inferior, membrane-covered round window
The middle ear cavity, or tympanic cavity
runs obliquely downward to link the middle ear cavity with the throat, and the mucosae lining the two regions are continuous.
pharyngotympanic tube, or auditory tube
Inflammation of the middle ear, is a fairly common result of a sore throat, especially in children, whose pharyngotympanic tubes run more horizontally.
otitis media
The tympanic cavity is spanned by the three smallest bones in the body, which transmit the vibratory motion of the eardrum to the fluids of the inner ear
ossicles
The internal ear is a maze of bony chambers
called the
bony labyrinth, or osseous labyrinth
The three subdivisions of the bony labyrinth are the spiraling
- Cochlea
- Vestibule (is situated between)
- Semicircular canals
These bones, named for their shape
- Hammer or Malleus
- Anvil or Incus
- Stirrup or Stapes
The bony labyrinth is filled with a plasma-like
fluid
perilymph
Suspended in the perilymph, a system of membrane sacs that more or less follows
the shape of the bony labyrinth.
membranous labyrinth
The membranous labyrinth itself contains a thicker fluid called
endolymph
what is does is respond (frequently without our awareness) to various head movements.
equilibrium
The equilibrium receptors of the inner ear, collectively
vestibular apparatus
Within the membrane sacs of the vestibule are
receptors that are essential to our sense of equilibrium
maculae
maculae “spots” that are essential to our sense of
sense of equilibrium
report on changes in the position of the head in space with respect to the pull of gravity when the body is not moving
maculae
Each macula is a patch of receptor (hair) cells with their “hairs” embedded, a gelatinous mass studded with otoliths
otolithic membrane
tiny stones made of calcium salts that is studded with
otoliths
receptors, found in the semicircular canals, respond to angular or rotational movements of the head rather than to straight-line movements.
dynamic equilibrium
are multiple receptor regions, which consists of a tuft of hair cells covered with a gelatinous cap
crista ampullaris
a gelatinous cap that covered tuft of hair cells in crista ampullaris
cupula
the endolymph-containing membranous labyrinth of the cochlea is within
cochlear duct
the endolymph-containing membranous labyrinth of the cochlea , which contains the hearing receptors, or hair cells
spiral organ of Corti
Sound waves that reach the cochlea through vibrations of the eardrum, ossicles, and oval window set the cochlear fluids into
motion
is increased by the lever activity of the ossicles as the sound waves are transmitted by the ossicles from the eardrum to the oval window
their force (amplitude)
nearly the total force exerted on the much larger eardrum reaches the tiny oval window, which in turn sets the fluids of the inner ear into motion, and these pressure waves set up vibrations in the
basilar membrane
The receptor cells, positioned on the basilar membrane in the spiral organ of Corti, are stimulated by the vibrating movement of the basilar membrane against the gel-like
tectorial membrane
the hair cells transmit impulses along a (a division of cranial nerve VIII—the vestibulocochlear nerve) to the auditory cortex in the temporal lobe, where interpretation of the sound, or hearing, occurs.
cochlear nerve
is defined as hearing loss of any degree—from a slight loss to a total inability to hear sound.
deafness
a ruptured eardrum, and otitis media (inflammation of the middle ear)
otosclerosis
occurs when there is degeneration or damage to the receptor cells in the spiral organ of Corti, to the cochlear nerve, or to neurons of the auditory cortex.
Sensorineural deafness
The exact cause of this condition is not fully known, but suspected causes are arteriosclerosis, degeneration of cranial nerve VIII, and increased pressure of the inner ear fluids.
Ménière’s syndrome
