The Ear Flashcards
What is the external acoustic meatus
A sigmoid shaped tube that extends from the deep part of the concha to the tympanic membrane
What are the external 1/3 of the ear formed by
Cartilage
What is the inner 2/3 of the ear formed by
The temporal bone
What is the middle ear filled with
Air
Where does the tympanic membrane lie
At the distal end of the external acoustic meatus
What is the tympanic membrane
Connective tissue structure covered with skin on the outside and a mucous membrane on the inside
The membrane is connected to the surrounding temporal bone by a Fibrocartilaginous ring
Is the tympanic membrane translucent
Yes
What do compression waves in the air (sound waves) cause in the ear
The tympanic membrane to vibrate which is amplified and transmitted by the ossicles to the oval window
What are the 3 ossicles
Malleus
Incus
Stapes
What happens once a vibrations has reached the oval window
They are converted into waves in the perilymph fluid of the inner ear
What is the innervation of the stapedius
A branch of the facial nerve (nerve to stapedius)
What does the tensor tympani in the ear do
Pulls the manubrium of the malleus medially tensing the tympanic membrane and dampening movement in response to loud noises
What is the innervation of the tensor tympani in the ear
By a branch of the mandibular division of the trigeminal nerve
What type of epithelium is the pharyngotympanic tube
Ciliated columnar epithelium
What 3 parts of the ear are housed in the temporal bone
Cochlea
Vestibule
Semicircular canals
What are the 3 parts of the bony labyrinth
Vestibule
Cochlea
Semilunar canals
What is the endolymph
Clear potassium rich fluid filling the membranous labyrinth
What is the membranous labyrinth
Utricle and saccule inside the vestibule, cochlear duct and membranous semicircular ducts
What is the perilymph
Surrounds the membranous labyrinth filling the space between the membranous tunnel and its contents and the bony walls that surround it
What is the modiolus
Cone shaped core of bone that houses the spiral ganglion which consists of cell bodies of the first sensory neurons in the auditory relay
What does the cochlear duct contain
Endolymph
What is the upper section of the cochlea called
The scala vestibuli
What is the lower section of the cochlea called
Scala tympani
Where does the cochlea divide into two sections
In the cochlear duct which is inside the cochlea
What are both sections of the cochlea filled with
Perilymph
What part of the basilar membrane deals with high frequency sound waves
They vibrate the narrow portion near the oval window
Which part of the basilar membrane deals with low frequencies
The wider, thicker portion near the apex of the cochlea
What is stimulated for hearing to occur
The auditory area of the cerebral cortex
What is the pathway of sound waves
Enter external auditory canal
Strike tympanic membrane causing vibrations
Tympanic vibrations move the malleus which in turn moves the incus and then the stapes
The stapes moves against the oval window which begins the fluid conduction of sound waves
What do the hair cells in the ear do
Move against the tectorial membrane stimulating the dendrites that terminate around the base of the hair cells and initiates impulse conduction by the cochlear nerve to the brain stem
What do impulses for hearing pass through before reaching the temporal lobe
Relay station in the nuclei in the medulla, pons, midbrain and thalamus before reaching the auditory area o f the temporal lobe
What is the vestibule
The central section of the bony labyrinth the utricle and saccule are the membranous structures within the vestibule
How many semicircular canals are there found in the temporal bone
3
What do each semicircular canal contain and connect with
Contain endolymph and connects with the utricle
How does sense of balance occur
Movements of the maculae located in both the utricle and saccule provide information related to head position or acceleration
Where are otoliths located
Within the matrix of the macula
What causes the cupula to lean in the opposite direction
As the endolymph is not attached to the skull it does not move immediately leading to tension in the tip links causing mechanical opening or closing of ion channels leading to the influx of ions terminating in the propagation of impulses along the vestibular branch of the vestibulocochlear nerve
How do the impulses travel
To the vestibular nucleus and from there to the cerebellum
Which parts of the ear are mainly responsible for forward/backward and up/down motion detection
The utricle and saccule in the vestibule
How does your ear detect motion and fix it
Fluid in semicircular canals shift the tiny hairs triggering activity in vestibule which are connected by sacs called saccule and utricle which also contain tiny hairs to sense movement
Therefore semicircular canals and vestibule let your brain know about the movement
What are the 3 nerves which go to the ear
Facial
Vestibular nerve
Auditory nerve
