The Ear Flashcards
what is the main osteological part of the ear?
pectoris temporal bone
what are the three parts of the human ear?
- external ear
- middle ear
- internal ear
what is the function of the ear?
organ of hearing and balance
what makes up the external ear? what is the function?
Auricle & External Acoustic Meatus
- directs sound waves toward tympanic membrane/inner ear
what makes up the middle ear? what is their function?
Ossicles
- mechanically transmit sound
what part of the ear is connected to the nasopharynx?
The middle part of ear via the auditory tube
what is found within the internal ear? what is their function?
Semi-circular Canals
- motion
Cochlea
- hearing
how are mechanical signals conveyed by the ossicles transmitted?
via CNVIII (vestibulocochlear) towards brain
what is the visible part of the ear called?
auricle
what is the auricle composed of?
elastic cartilage
how long roughly is the external acoustic meatus?
2.5cm long
what is the lateral 1/3rd of the external acoustic meatus composed of?
cartilage
what is the medial 2/3rds of the external acoustic meatus composed of?
bone
what epithelium is found in the external ear?
stratified squamous epithelium
what is the located in the dermis of the external ear?
- hair follicles
- glands
- ceruminous glands
- blood vessels
- nerves
what are ceruminous glands?
modified sweat glands that secrete ear wax
how is the tympanic membrane held within the temporal bone?
fibrocartilaginous ring
what is the tympanic membrane?
an oval, semitransparent structure situated between the external auditory meatus & the tympanic cavity of middle ear
name the ossicles of the ear:
- malleus
- incus
- stapes
what is the function of the auditory tube?
connects middle ear with the nasopharynx and allows for pressure equalisation between the middle ear & atmospheric pressure
why can respiratory infections sometimes cause problems with the ear?
the auditory tube is a potential route for the spread of infection from the nasopharynx to the ear
where does the facial nerve enter the petrous temporal bone?
internal acoustic meatus
what branches does the facial nerve give off during its course though the middle ear?
- greater petrosal nerve
- chorda tympani nerve
what is the function of the greater petrosal nerve (that comes off of the facial nerve)?
carries parasympathetic fibres to the pterygopalatine ganglion to stimulate the parotid gland
the roof of the middle ear is very thin, what clinical implication can this lead to?
any infections of the ear can spread into the cranial cavity
what nerve runs along the upper portion of the tympanic membrane?
chorda tympani
what is the clinical name for a middle ear infection?
otitis media
what is otitis media with effusion?
ear infection that causes a build up of fluid in the middle ear behind the tympanic membrane
how may otitis media with effusion be treated?
a grommet may be placed
what can chronic infections of the middle ear lead to?
- conductive deafness due to damage of the ossicles
- mastoiditis
if a patient requires surgery to the middle ear, why is this potentially dangerous?
close proximity to facial nerve
what is the bony labyrinth?
the fluid filled space located around the otic capsule
what part of the internal ear is concerned with hearing?
the cochlea
what parts of the inner ear are concerned with balancing?
- vestibule
- semicircular canals
what fluid is located in the bony labyrinth?
perilymph that contains endolymph
what is the function of the vestibulocochlear nerve?
conveys the sensation of motion and hearing
- split into two parts
what are the divisions of the vestibulocochlear nerve & their functions?
Cochlear part = hearing part
Vestibular part = equilibrium and balance
what are the different types of hearing loss?
- neural hearing loss
- conductive hearing loss
how can neural hearing loss occur?
damage to the cochlear part of CNVIII
what can damage to the vestibular part of CNVIII cause?
- ataxia
- vertigo
- nausea
(bc its responsible for balance & equilibrium maintenance)
what bone lies in the fenestra vestibuli?
the stapes
what can be used to examine the tympanic membrane?
otoscope
what may enlarged & tender lymph nodes indicate?
infection present
what may hard, painless enlarged lymph nodes suggest?
malignancy