The Ear Flashcards
Name the parts of the external ear
What are the common signs and symptoms of ear pathology
Otalgia
Tinnitus
Vertigo
Discharge from ear
Hearing loss
Facial nerve palsy
What are the main nerves that carry sensation from the ear
C2 and C3
Vagus nerve
Auriculotemporal nerve - trigeminal
Tympanic nerve - glossopharyngeal
(Facial nerve)
What lines the external auditory meatus
Keratinising, stratified squamous epithelium/skin
Has hair, sebaceous and ceruminous glands
Ceruminous - produce cerumen
Outer 1/3 is cartilaginous while inner 2/3 is bony
What is the tympanic membrane
Fibrous structure at most medial end of external auditory meatus
Has shallow cone shape with apex pointing medially
Is translucent -> allows visualisation of structures in middle ear
Name the structures that you would expect to see on a normal otoscope
What are the ossicle
Three bones found in the middle ear connected by synovial joints
They amplify and relay vibrations from tympanic membrane to the oval window
Ossicles are the malleus, incus and stapes
What nerve innervates the middle ear
Glossopharyngeal nerve
What muscles tamper with the ossicles and what does this prevent
Tensor tympanic
Stapedius
These muscles contract to prevent excessive vibration due to loud noise
What tube is found in the middle ear cavity, what does it connect with and what is its function
Pharyngotympanic/Eustachain tube
Connects with the nasopharynx to equilibrate pressure of the middle ear
Also allows ventilation of and drainage of mucus from middle ear
Why do we need the Eustachian tube to equilibrate the pressure inside the middle ear
Mucous membrane of middle ear continuously reabsorbs air in middle ear resulting in -ve pressure
By equilibrating the air in the middle ear, the Eustachian tube prevents build up of a -ve pressure inside the middle ear
What cells does the middle ear connect with
Mastoid air cells via mastoid aditus and antrum
What is the inner ear formed of and what else is it known as
Inner ear is formed of vestibular apparatus and cochlea
Inner ear is also known as the labyrinth
How does the cochlea detect sound
Cochlea houses the spiral organ of Corti - houses stereocilia
Vibrations at oval window set up movement of fluid in the cochlea -> waves of fluid cause movement of stereocilia
Movement of stereocilia within cochlear duct generates APs in CN VIII
What is the vestibular apparatus formed of
Fluid-filled tubes with specialised hair cells that generate APs when moved
Includes semi-circular ducts, saccule and utricles
