Flashcards in Ears Deck (58)
Between what frequency range can we detect sound?
20Hz to 20kHz
The outer part of the ear is known as the X (cartridge covered in skin), it ends posteriorly in a fleshy lobule. The large outside rim is called the Y.
X= Auricle or pinna
What is the medical name for earwax, where is it produced?
Made by modified sweat glands lining EAM
What is the sensory innervation of the EAM and tympanic membrane?
Auriculotemporal branch of V3 (Mandibular from CN V)
Auricular branch of vagus (CN X)
What is the name for the central attachment point on the tympanic membrane, what does it attach to?
Attaches to the handle of the malleus
The tympanic membrane is sloped so its lateral surface points which way?
Inferior and anterior
How does the body equalise pressure between the middle ear and atmosphere?
The eusachian tube runs from the ant wall of the middle ear to the lateral wall of the nasopharynx. It's 3-5cm long and opens to equalise pressure but it also drains mucus from the middle ear
How does vibration travel along the three ossicle bones?
TM > Handle of malleus > head of malleus > incus > stapes
How is vibration passed from the stapes to the perilymph and then where does it go?
Stapes > oval window (connects mid and inner ear) > scala vestibuli > helicotrema (apex) > scala tympani > round window - then dissipates
How does the cochlear detect sound?
Disortion of the basilar membrane makes the hair cells of the organ of corti vibrate against the tectorial membrane just below, this displaces the sterocilia, allows an influx of ions and depolarises the cell
Where are high pitched and lower pitched sounds detected in the cochlear?
Low frequency (long wavelength)- AT HELICOTREMA (apex)
High frequency (short wavelength)- Near oval window
Fibres from the cochlear duct then travel where?
Via CN VIII to:
Cochlear nucleus (brainstem) > inf colliculus > medial geniculate nucleus in thalamus > auditory cortex
Do we use the ipsilateral or contralateral brain when processing auditory information?
Most fibres (in cortex or inf colliculus) are from the contralateral side however some remain from the ipsilateral side in order to help localise sound
What changes occur in the ear with age?
Ear drum + ossicle articulations stiffen, hair cells are damaged and the round window ossifies
(all cause hearing loss)
Which nerve carries information from the taste buds, then passes through the middle ear? Which CN does it join and where?
Corda tympani nerve
Joins facial nerve in facial canal then immediately exits skull via stylomastoid foreamen
The majority of the ear is contained within which bone?
Petrous part of temporal bone
What are the two parts to the middle ear?
Tympanic cavity proper- Everything opposite tympanic membrane
Epitympanic recess- All above membrane level (sup half of malleus and incus)
What is the OIAN of the tensor tympani muscle?
O: Cartlidge of eustachian tube
I: Handle of malleus
A: Tenses tympanic membrane (make sound quieter)
N: Mandibular nerve (V3)
What is the OIAN of the stapedius muscle?
O: Pyramidal prominence
I: Neck of stapes
A: Stabilises stapes and tightens annular ligament to dampen sound
N: Facial nerve (CN VII)
Where is Wernicke's area and what is its function?
Sup temporal gyrus in dom (L) hemisphere
It does sounds to words (comprehension + understanding)
Where is brocha's area and what is its function?
Inf frontal gyrus in dom (L) hemisphere
It does words to sounds (motor programming for speech)
What seperates brocha's and wernicke's area's?
What is aphasia?
Acquired disorder. Problems either using or understanding language
Which nucleus and cortical area's are the primary governors of attention?
Pulvinar nucleus (connects to many cortical area's)
Inf parietal lobe primary cortical region which governs attention
The inner ear is found in which bone portion?
Otic capsule in petrous part of temporal bone
What is the vestibular labrynth, what does it detect and how does it do it?
Contains the otolith organs (utricle and saccule)
Detects acceleration, has special sensory epithelium (maculae) with hairs which detect endolymph movement
What do the utricle and saccule each detect?
Utricle (hair on floor)- Detects horizontal acceleration
Saccule (hair of medial wall)- Detects vertical acceleration
What is the role of the semicircular canals?
Carry the semicircular ducts- contain receptors called ampullary crests. These detect movement of endolymph at the ampulla of each duct (detects angular movement)
Which type of movement is each semicircular canal responsible for detecting?
Ant (sup): Flex/ extension (nodding)
Post: Lat flexion (Head to shoulders)
Lat: Axial rotation (shaking head)