Hearing Flashcards
How is sound transmitted to the ear?
Sound waves (mechanical energy in the form of air virbations) in the outer ear are convereted into kinetic energy moving the tympanic membrane and middle ear ossicles and then converted into electrical energy by the cochlea in the inner ear.
- Sounds waves mechanical energy from air vibration –> kinetic energy by tympanic membrane and ossiles –> electrical energy by cochlea in the inner ear.
What does the outer ear consist of?
- Consists of the Pinna - the visible part of the ear, this focuses sound waves
- Tragus = goat
- Helix - spiral
- conchae = shells
- lobule = small lobe
- External auditory canal
- Tympanic membrane
What does the middle ear consist of?
The middle ear is an air filled chamber communicating to the outside via the pharyngotympanic tube (eustachian tube) to equalize pressure between the outer environment and the middle ear.
The middle ear contains the ossicles - these function to equalize the differences in energy impedances between the air waves and cochlear waves.
- Malleus = hammer - attached to the TM
- Incus = anvil - in between
- stapes - stirrup, attaches to the oval window
The middle ear also contains the stapedius muscle - this is innervated by the facial nerve and acts to dampen the virbations of stapes.
Tensor tympani muscle - Mandibular branch of trigeminal nerve - dampens loud sounds and sound of chewing by dampening the virbation of the tympanic membrane
Also contains the round window - allows for movement/displacement of fluid when the stapes presses on the oval window.
What does the inner ear consist of? what does the organ of corti do.
Cochlea - houses the organ of Corti, a receptor organ of hearing that converts mechanical to neural energy.
Mechanical energy propgates through the scala vestibuli (begins wiht the oval window, perilymph) then to the scala tympani (ends with the round window, periplymph)
The mechanical energy transmits to the organ of corti in the scala media (endolymph) across the reissner membrane, which then stimulates a neural impulse ot the cochlear portion of the vestibulocochlear nerve CN8.
In the weber test, if the sound lateralizes to the impaired ear what does it indicate
indicates conductive hearing loss
in the weber test if sound conducts to the unaffected ear, what does it indicate?
Suggests sensorinuerla hearing loss in the impaired ear.
Normal vs abnormal Rinne
Normal is AC>BC
What is vestibular function?
Semiciruclar canals contribute to the sense of balance and spatial oreintation (along with the eyes, cerebellum, spinal cord, and proprioceptive senses) in order to coordinate movement with balance.
Where does the majority of sensorineural hearing loss occur?
Organ of Corti - secondary to loud environmental noise
What is epistaxis caused by?
Arterial bleeds in the nose. Arterial supply to nasal cavity is extensive anatasomosos that create Keisselbach’s plexus in the medial wall - the septum
- ICA
- posterior and anterior ethmoid aa brancehs of the opthalmic artery
- ECA
- spehnopalatine = “artery of epistaxis” - terminal branch of maxillary artery via the pterygopalatine fossa then sphenopalatine foramen
- greater palatine - branch of maxillary a via pterygopalatine fossa through palatine canal and creater palatine foramen
- superior labial from facial a
- lateral nasal -lateral wall - from facial a
What is the main cause of sinusitis?
Main cause of sinusitis is the obstruction of draining in the pathways of sinuses. Clearing obstruction is function of sinus surgery
Drainage occurs via the osteomeatal unit which is composed of frontal recess, middle turbinate, anterior ethomid sinus, ethomoid bullae, uncinate process, maxillary infundibulum, hiatus semilunaris (gutter like space below the middle turbinate), and maxillary ostium
Blockage of the osteomeatal unit prevents effective mucocilary clearence, leading to stagnation of clearence of mucus and acute and chronic sinusitis.
Osteometal pathway
The frontal, maxillary, anterior, middle ethmoidal sinuses drain into the middle meatus area.
Where is swallowing coordinated?
By swallowing center in the medulla, and pons - the bulb.
Initiated by touch receptors in the pharynx.
Four phases of swallowing
Oral prepatory phase - food processed by mastication (V3) and salivation (VII) into bolus
oral phase(buccal)- bolus moved to back of tongue, antieor tongue lifts to the hard palate and posteriorly to force bolus into orophayrnx. Posterior tongue lifted by mylohyoid m, elevating soft palate and sealing the nasopharynx.
Pharygneal phase- bolus advanced form pharynx to esophagus. Soft palate is elevated to posteioer nasopharyngeal wall by levator veli palatini. Superior constrictors bring palatopharyngeal folds together. Larynx and hyoid are elevated and pulled forward
(V,X,XI,XII)
Esophageal phase - X -
What is the inferior pharyngeal constrictor made of?
- Thyropharyngeal constrictor, cricopharyngeal constrictor.
