Anatomy/Physiology of Ear Flashcards
What is the epithelium of the external ear?
Stratified keratinising squamous epithelium
What is the lateral 1/3rd of the external auditory meatus composed of?
Skin and cartilage
What does the skin of the external auditory meatus contain for producing wax?
Ceruminous and sebaceous glands
Hairs of the external auditory meatus provide
a barrier and source of disinfectant
Medial 1/3rd of external auditory meatus is composed of
skin and bone
Where does the skin of the external auditory meatus grow from?
From the jumbo of the tympanic membrane outwards
Where is the skin of the external auditory meatus shed?
Lateral 1/3rd of the canal, trapped in the wax as part of cleaning
What is the epithelial lining of the external ear canal?
Simple squamous epithelium
Components of the middle ear
Eustachian tube
Tympanic membrane
Mastoid bone
Ossicles - malleus, incus and stapes
What is the epithelial lining of the eustachian tube?
Respiratory epithelium that becomes pseudostratified as it approaches the nasopharynx
Layers of the tympanic membrane
Outer squamous epithelial layer
Middle fibrous connective tissue
Inner columnar ciliated mucous membrane
Function of the ossicles
Sound conduction
What might occur as a result of trauma to the ossicles?
Chronic suppuration
Bony sclerosis
What is the epithelial lining of the middle ear?
Columnar ciliated epithelium
Contents of the middle ear
Ossicles
Facial nerve
Chorda tympani
Connections of the middle ear
To the mastoid system via the aditus, to post-nasal space via Eustachian tube
Important relations of the middle ear
Middle fossa
Internal jugular vein
Internal carotid artery
What are the possible consequences of damage to the ear/facial nerve in surgical treatment of the ear
Infection Trauma Intracranial sepsis Facial nerve damage Deafness Dizziness
What are the contents of the bony labyrinth of the inner ear?
Cochlea
Vestibule
Semi-circular canal
What fluids are contained within the membranous labyrinth?
Perilymph
Endolymph
Audiometry measures
hearing acuity for changes in amplitude/intensity and frequency of sound
Tympanometry measures
tympanic membrane compliance
Children born deaf will not be able to develop normal speech unless hearing is restored by what age?
4
Where does the cochlear nerve join the brainstem?
At the junction of the pons and medulla
What nerves supply innervation to the ear?
Cervical nerve root branches
Trigeminal
Glossopharyngeal
Vagus
What is the basic pathway affected in conductive hearing loss?
Ear canal -> tympanic membrane -> ossicles
What is the basic pathway affected in sensorineural hearing loss?
Cochlea -> cochlear nerve -> auditory cortex
