Ear Flashcards
cerumen
ear wax. part seaceous secretions, part skin
lateral 1/3 of external ear is what
cartilaginous
medial 2/3 of ear is what
bone
Middle ear
contains ossicles
transmits sound waves into mechanical energy which is imparted into fluid environment of ear
Internal Ear
fluid filled compartment
has multiple compartments with different ionic compositions
ionic differences helps detect fluid movment
Epithelium in middle ear
simple squamous/cuboidal with interspersed goblet cells
External layers of typanic membrane
thin epidermis
made of stratified squamous epithelium
continuous with thin skin of external acoustic meatus
Intermediate layer of tympanic membrane
collagen and elastic fibers radiate out and fill this layer
fibroblasts will regenerate the tympanic membrane if it’s perforated
Internal surface of tympanic membrane
continuous with middle ear cavity epithelium
simple squamous to simple cubodial
2 exit pathways of the middle ear
auditory (eustachian) tube and mastoid air cells
Ossicles are lined with what
simple squamous (and cubodial) epithelium
Tensor tympani
muscle attached to malleus
innervated by CN V
Stapeius
muscle attached to stapes
innervated by CN VII
Damage to CN V and CN VII leads to what
tinnitus
Auditory (Euchatian) tube
lined with pseudostratified columnar epithelium with goblet cells
equalizes pressure between middle ear and nasopharynx
Bony Labryinth
Found within the petrous portion
contains the membranous labyrinth
membranous labyrinth
series of sacs and tubules
has specialized sensory cells
Endolymphatic space
between inside wall of the bony labyrinth and the outer wall of the membranous labyrinth
perilympatic space
inside of the membranous labyrinth
cortilymphatic space
intercellular region found in the oragn of corti inside the cochlea
Oval window
where the footplate of stapes sits
inlet into the bony labryinth
round window
covered in secondary tympanic membrane
allows pressure release
vestibule
middle enlargement where the oval window sits
both cochlea and semicircular canals meet here
semicircular canal
2 orthogonal arches
swell as they meet the vestibule
Angular movement
sensing our position in space. done by semicircular canals
Cochlea
detects sound
Ions in endolymph
high in K+, low in Na+
utricle and saccule
detect linear movement
Type I hair cells
afferent nerve ending surrounds the entire cell
Type II hair cells
afferent nerve ending sits at base of cell
Kinocilia
have traditional cilia structure
Stereocilia
are projections of the plasma membrane
Crista Ampullaris
senses angular, rotational movements of head
Otolithic membrane
similar to crista ampullaris
has gelatinous caps and hair cells
Otoliths
bone fragments which sit on gelatinous caps
unique to macula
can be unseated, causing vertigo
Scala media
filled with endolymph
Scala vestibuli
space above cochlear duct when looking at coronal section
opening is located on vestibule
vibrations travel here first
filled with perilymph
Scala tympani
space below cochlear duct when looking at coronal section
filled with perilymph
vibrations exit here
Oval window leads to what
scala vestibuli
round window leads to what
scala tympani
Triangular space
medial tip of triangle is modiolus, the body core
lateral wall is the bony cochlear wall
Bestibular (reissner’s membrane)
top of triangle
divides the scala vestibuli from the scala media
Stria Vascularis
structure that makes endolymph
found on lateral wall of scala media
High in potassium
Basilar membrane
floor of triangle
divides scala tympani from scala vestibuli
spiral organ of corti sits on this
Phalangeal cells
support cells for hair cells
inner phalangeal cells surround the inner hair cells completely
Pillar cells
form inner spiral tunnel
Tectorial membrane
colalgen type II, V, and IX
otogelin and tecorin -glycoproteins
supported by the sterocilia of hair cells
