Ear Flashcards
What are the two functions of the ear?
Hearing and balance
“receptors turn sound, movements of the head and the body’s response to gravity into an electrical energy”
What is the function of the auricle?
Sound localization and amplification
Describe the skin of the auricle.
Think skin with hair follicles, sweat, and sebaceous glands
Does the external acoustic meatus have sweat glands?
NO
It is lined with thin skin and ceruminous glands
What does cerumen contain?
Cerumen contains desquamated skin cells, secretions from sebaceous and ceruminous glands
The lateral 1/3 of the external acoustic meatus is ________ and the medial 2/3 is ___________.
lateral 1/3 = cartilage
medial 2/3 = temporal bone
What is the significance of fibroblasts in the intermediate layer of the tympanic membrane?
you can regrow the tympanic membrane
Describe the external surface of the tympanic membrane.
thin epidermis
Describe the intermediate layer of the tympanic membrane.
- collagen and elastic fibers arranged radially and circularly with fibroblasts
Describe the internal surface of the tympanic membrane.
- Simple squamous to simple cuboidal epithelium
- Mucous membrane of the middle ear cavity
What are the two functions of the middle ear?
1) Convert sound waves into mechanical vibrations
2) Transmit vibrations to the internal ear
What is the lining of the middle ear?
simple squamous epithelium
-also on the surface of the ossicles
Loss of function of the middle ear results in what?
Conductive hearing loss
What are the three ossicles?
1) Malleus (hammer)
2) Incus (anvil)
3) Stapes (stirrup)
Within what bone are all the ossicles located?
Petrous portion of the temporal bone
The tensor tympani is connected to which ossicle? What is its function?
Malleus
Functions to increase the tension of the tympanic membrane (CN V)
The stapedius is connected to which ossicle? What is its function?
Stapes
Dampens movement of the stapes on the oval window (CN VII)
What is the attenuation reflex? What muscles are involved?
Reflex that protects the internal ear form damaging loud sounds
Tensor tympani and stapedius
What is otosclerosis?
Bone remodeling causes the stapes to be fixed onto the oval window
What structure is associated with otitis media?
Auditory (eustachian) tube
What structures does the auditory/eustachian tube connect?
Connects the middle ear cavity to the nasopharynx
What type of cells line the eustachian tube?
Transitions from simple squamous epithelium to pseudostratified columnar epithelium with goblet cells
What is the function of the eustachian tube?
Equalize pressure in the middle ear with atmospheric pressure
Where are mastoid air cells located?
Within the mastoid process of temporal bone
What type of cell lines the mastoid air cells?
simple squamous epithelium
Which structure am I describing: “a membranous labyrinth, series of sacs and tubules, suspended within a bony labyrinth”
The internal ear
What is the fluid filled space within the membranous labyrinth called?
Endolymphatic space
What is the ion composition of endolymph?
High K, Low Na
What is the fluid filled space between the membranous labyrinth and bony labyrinth called?
Perilymphatic space
What is the ion composition of perilymph?
High Na, Low K
What is the fluid filled space within the tunnels of the organ of Corti of the cochlea called?
Cortilymphatic space
What is the ion composition of the cortilymph?
High Na, Low K
Where are the semicircular canals located?
Within the perilymphatic space