Exam #2: Ear Flashcards
Where is the internal ear located?
Petrous portion of the temporal bone
External Acoustic Meatus, bone vs. cartilage
- Lateral 1/3 is cartilage
- Medial 2/3 is bone (temporal)
What are the three layers of the TM?
1) External
2) Intermediate
3) Internal Surface
External Layer of the TM
- Thin epidermis
- Stratified squamous epithelium
Intermediate Layer of the TM
- Collagen, elastic fibers & fibroblasts
- Fibroblasts function in regeneration of the TM
Internal Surface of the TM
Simple cuboidal to simple squamous epithelium
What cell type lines the ossicles?
Simple squamous epithelium
Malleus
- Tensor Tympani Muscle
- CN V
- Function: to dampen loud sounds
Stapes
- Stapidus Muscle
- CN VII
- Function: to dampen loud sounds
What type of epithelium lines the Eustachian/ auditory tube?
- Remember: extension from the ear into the nasopharyx that takes on a respiratory epithelium
- Pseudostratified columnar epithelium with goblet cells
Bony Labyrinth
Perilymph
Membranous Labyrinth
Endolymph
Cortilymphatic Space
- Intercellular space in the Organ of Corti
- Perilymph-like composition
What is the cochlea coiled around?
Mediolus
Cochlea
Sound
Vestibule
- Space between the cochlea & semicircular canals
- Linear movement
- Saccule & Utricle
Semicircular Canals
- Rotational/ angular movement
- Amuplla region contains hair cells
Ampulla
- Swelling in the semicircular canals as they attach to the vestibule, which contains hair cells
Which part of the inner ear contains the oval window, and which contains the round window?
- Oval window= vestibule
- Round window= cochlea
Perilymph
- Bony Labyrinth
- ECF
- High Na+, Low K+
Endolymph
- Membranous Labyrinth
- ICF
- High K+, Low Na+
Crista Ampullaris
- Sensory part of semicircular canals
- Rotational/ Angular movement
Spiral Organ of Corti
Contains hair cells in the cochlea for hearing
Movement Hair Cells: Type I vs. Type II
- Type I= afferent neuron surrounds entire cell
- Type II= afferent neuron sits only at the base
Kinocilia
- Large pole region of cell
- Cilia structure
Stereocilia
- Smaller projects of the apex of the hair cell adjacent to kinocilia
- Specializations of the plasma membrane
What can increased pressure in the endolymph cause?
- Accidental stimulation of the hair cells
- Vertigo
- Tinnitus
Cupula
- Gelatinous substance in the crista ampullaris that the hair cells imbed into
- NO Otoliths associated
- Type I & Type II hair cells
Macula
- Region of the utricle & saccule that contains sensory receptors
- Linear movement
- Otoliths
What type of movement does the utricle sense?
Horizontal
What they of movement does the saccule sense?
Vertical
Three compartments of the cochlea (top–>bottom)
1) Scala Vestibule (Perilymph)
2) Scala Media (Endolymph)
3) Scala Tympani (Perilymph)
Helicotrema
apex of the cochlear duct/ scala media
Vestibular Membrane (Reissner’s Membrane)
- Divides the Scala Vestibule from the Scala Media
- Two layers of squamous epithelium
- Tight junctions to maintain ion concentrations
Scala Vascularis
- Produces endolymph in the Scala Media
- Located on the lateral/outer wall
Basilar Membrane
- Divides the Scala Media & Scala Tympani
- Organ of Corti sits ontop
Phalangeal Cells
- Support the hair cells in the Organ of Corti
- Form the outer & inner tunnels that contain cortilymph
Pillar Cells
Structural cells in the Organ of Corti
Tectorial Membrane
- Where hair cells imbed in the Organ of Corti
- Contains Type II, V, & IX Collagen
- Contains Otogelin & Tectorin, glycoproteins
How are the hair cells of the Organ of Corti different from the other parts of the inner ear?
- No kinocilium
- Stereocilia are all the same length/ symmetrical
What is the difference between an inner & outer phalangeal cell?
Inner= encompass the entire hair cell Outer= do NOT encompass the entire hair cell
Vestibular Ganglion
Located in the internal auditory meatus
Cochlear Ganglion
Located in the Cochlea
Which end of the basilar membrane is responsible for high pitched sounds?
Base
