Ear Flashcards
What structures do sound waves pass through before reaching the auditory receptors?
External auditory canal - timpani membrane - malleus - incus - stapes - oval window - fluid of inner ear - fluid filled cochlear - sensory hair cells in membrane of spinal organ
What is the tympanic membrane?
Fibrous membrane separating the auditory canal from the middle ear
Which three bones make up the ossicles?
Malleus
Incus
Stapes
What is the function of the ossicles?
To transmit sound from the ear drum to oval window
What structure connect ossicles to scala vestibule?
Oval window
As stapes footplate moves into oval window the membrane of what moves out?
The round window
What does the auditory tube connect?
The nasopharynx to middle ear - equalises pressure between atmosphere and middle ear - drains mucus from inner ear
What lines the external auditory canal?
Ear wax
what is ear wax made from?
Viscous secretions from sebaceous glands, less viscous from apocrine sweat glands, shed layers of skin, fatty acids, alcohol, squalene and cholesterol
What is chorda tympani and what does it innervate?
It is a branch of the facial nerve
It provides taste to the anterior 2/3 of the tongue
parasympathetic supply to submandibular and sublingual glands
What forms the lateral wall of the middle ear (air filled chamber)?
Tympanic membrane
What is the middle ear connected to posteriorly?
The mastoid air cells
Where are the tensor tympani and stapedius muscles located?
The middle ear
What is the function and innervation of tensor tympani?
Contraction = pulls handle of malleus medially Innervation = Trigeminal nerve v3
What is the function and innervation of stapedius?
Contraction = pulls stapedius posteriorly Innervation = facial nerve branch
What is the inner ear?
A bony labyrinth - filled with perilymph
How many types of receptors are in the membranous labrinth?
3 - maculae
- Christae ampullaris
- Spiral organ
Which receptors of the membranous labrinth are vestibular receptors?
Maculae and Christae ampullaris
Where are the maculae located?
Utricle and saccule
What type of receptor is the spiral organ?
Auditory receptor
Which type of receptor is concerned with balance (providing sensory info about the static position of head in space)
Maculae
What is the function of Christae ampullaris?
Involved in change in direction and rate of movement
What are the similarities between Christae ampullaris and Maculae?
Hair cells have the same morphological forms
Hair cells are supported by single layer of columnar cells
Hair cells have numerous sterocilia
What can nystagmus and vertigo be a result of?
Injury to the peripheral vestibulocochlear
What is nystagmus?
Rapid involuntary eye movements
What is the organ of corti?
Specialised region in the cell wall of the cochlear duct
Where does the basilar membrane vibrate if its high frequency noise?
Near end - base (oval window)
Where does the basilar membrane vibrate if its low frequency noise?
Far end - apical end (helicotrema)
What fibres of the sensory bodies contact the hair cells?
Spiral ganglia
