Ear: Anatomy and Physiology Flashcards
what makes up the external ear?
the pinna, the external auditory canal to the tympanic membrane
name the three parts of the ear
> external ear
middle ear
inner ear
describe the pinna of the external ear
> helix ridge round the edge of the ear > antihelix ridge bit inside a bit > lobule: lobe > triangular area > concha > meatus > tragus
what is the pinna and the auricle made from?
stratified keratinised epithelium and elastic cartilage
how long is the external ear canal in adults?
4cm long
describe the lateral 1/3rd of the external ear canal
> made of skin and cartilage
ceruminous and sebaceous glands producing wax
thick hairs becoming thinner
what are the functions of lateral 1/3 of the external ear canal?
protective barrier and disinfectant
what part of the external ear canal has no hairs or cilia and doesn’t produce wax?
the medial 1/3rd
describe the shedding of the external ear canal
the skin is being constantly renewed and shed. it grows from the umbo of the tympanic membrane outwards. it is shed in the lateral 1/3rd of canal trapped in wax as part of the cleaning mechanism
describe the inner layer of the tympanic membrane
continuous with skin
what tissue is the middle layer of the tympanic membrane made form?
fibrous tissue
what type of epithelium makes up the inner layer of the tympanic membrane?
ciliated columnar epithelium with goblet cells
how large is the tympanic membrane?
1cm in diameter
describe the three bones from the tympanic membrane
malleus > incus > stapes
what is the function of the ossicles?
they conduct sound waves from tympanic membrane to the inner ear
what can cause disruption of sound conduction by the ossicles?
trauma or bony sclerosis (otosclerosis)
what lines the middle ear?
continuous respiratory epithelium (that forms the inner layer of tympanic membrane)
is the continuous respiratory epithelium lining the middle ear mucous secreting?
yes
what does the middle ear connect to via the aditus?
the mastoid system
what connects the nasopharynx to the middle ear?
Eustachian tube
what does the middle ear contain?
facial nerve
what are the important anatomical relations to the middle ear?
> middle cranial fossa
internal carotid artery
sigmoid sinus and internal jugular vein
what are the six segments of the facial nerve?
> intracranial > meatal segment > labyrinthine segment > tympanic segment > mastoid segment > extratemporal segment
what is the taste anterior of the tongue supplied by?
chorda tympani
what is cholesteatoma?
skin in the middle ear has become keratinised squamous epithelium which can become destructive. can be congenital or acquired.
what is contained in the inner ear?
> bony and membranous labyrinth
cochlear
peripheral vestibular apparatus
vestibulochochlear nerve
what does the bony and membranous labyrinth contain?
fluid-perilymph and endolymph
what makes up the peripheral vestibular apparatus?
> utricle
saccule
semicircular canal
in hearing what window does the foot of stapes vibrate in?
oval window
what causes a pressure wave through the fluid in the cochlear?
the foot of stapes vibrating in the oval window
what do the hair cells in the organ of corti detect?
the pressure wave through fluid in the cochlear
what nerve transmits the detection of the pressure wave by the hair cells in organ of corti to the brainstem?
CNVIII- vestibulocochlear nerve
describe the inputs for balance sensation?
> vision
peripheral vestibular system
proprioception
what are the outputs for creating balance?
> gaze stabilisation
> postural control
what is responsible for detecting head rotation?
semicircular canals
describe the effect vestibule-ocular reflex
this inables you to fix you vision on an object even when your head is moving
what detects linear acceleration in a vertical plane?
saccule
what does the utricle detect?
linear acceleration in horizontal plane
what nerve provides sensation to the middle ear?
the tympanic branch of glossopharyngeal nerve CNIX
what does the auricular branch of the vagus nerve CNX supply?
sensation to the posterior half of external ear canal
what nerve supplies the anterior half of the external ear canal?
the facial nerve
what nerve supplies the pinna?
the mandibular branch of the trigeminal nerve CN V3
what does otalgia mean?
ear ache
