Ear Flashcards
What type of cartilage makes up the auricle?
Elastic cartilage
What part of the external acoustic meatus is cartilage? What makes up the other part?
1/3 is cartilage. Other 2/3 is bone
What is cerumen?
desquamated skin cells, secretions from sebaceous and ceruminous glands
What covers the external surface of the TM?
Thin epidermis (skin)
What is the internal surface of the TM? What type of epithelium?
simple squamous to simple cuboidal epithelium, which is the mucous membrane of the middle ear cavity.
What does the intermediate layer of the TM consist of?
Collagen and elastic fibers arranged radially and circularly with fibroblasts
What is the function of the middle ear?
Convert sound waves into mechanical vibrations
The middle ear is lined with what type of epithelium?
Simple squamous
Loss of middle ear function results in what?
Conductive hearing loss
What is the muscle that is attached to the malleus? What is its innervation?
tensor tympani (CN V3)
What is the muscle that attaches to the stapes? What is its innervation?
Stapedius. innervation = CN 7 via the lesser petrosal nerve
What is the function of stapes?
Dampens movement of the stapes on the oval window
What is the window that attaches the stapes to the inner ear: the oval or round window?
Oval
What is the function of the round window?
Provide an outlet for pressure changes in the inner ear
What is otosclerosis?
bone remodeling causing Stapes to be fixed onto the oval window.
The eustatian tube connects what to what?
Middle ear to the nasopharynx
What is the epithelial type that comprises the auditory tube?
Pseudostratifed columnar
What is the transition between epithelial types that occurs between the eustatian tube and the middle ear?
middle ear = simple squamous
Aud tube = pseudostratifed colunar
What lines the pseudostratified epithelial cells in the auditory tube?
Goblet cell
What is the function of the auditory tube?
Equalize pressure
What is the epithelium that lines the mastoid air cells?
Simple squamous (same as middle ear)
What are the three spaces that are in the inner ear?
- Endolymphatic space
- Perilymphatic space
- Cortilymphatic space
What is the endolymphatic space?
Space within the membranous labyrinth
What are the ions that are present within endolymph?
High K, low Na (like inside of cells)
What is the perilymphatic space?
Space between the membranous labyrinth and bony labyrinth
What is the ion composition of the perilymph?
High Na, low K (just like ECF)
What is the space within the organ of Corti in the cochlea?
Cortilymphatic space
What is the ionic composition of the cortilymph?
High Na, low K
The inner ear is in which bone?
The temporal bone
What type of epithelium lines the external auditory meatus, as well as the external TM?
STRATIFIED squamous
What is the significance of the presence of fibroblasts in the TM?
Allows TM to regenerate
What types of joints are in the malleus, incus, and the stapes?
Synovial
What is the epithelium that lines the malleous, incus, and the stapes?
Simple squamous (just like the inner ear)
What is the structure on the inner ear that has the oval window on it?
The vestibule
What are the ampulla in the inner ear?
The sphereical bony prominences that sit at the junction of the vestibule and the semicircular canals
What is the modiolus?
The central part of the chochlea, about which the chochlea turns
Where does the round window face?
The middle ear
What are the two divisions of the inner ear?
The chochlea and the semicircular canals
What is the structure that connects the cochlea to the vestibule?
The saccule
What is the vestibular labyrinth?
The semicircular canals
Where is the cortilymphatic space?
Within the cochlea
What are the two divisions within the vestibule?
The utricle and the saccule
What do the utricle and the saccule sense?
Linear movement
What do the semicircular canals sense?
Movement in the sagittal, frontal, and transverse plane
What is the sensory part of the semicircular canal called? Where is it located?
The crista ampullaris, located in the ampulla
What connects the cochlear labyrinth and the saccule?
ductus reuniens
Where is the organ of corti?
In the cochlear duct
What are the two types of hair cells within the ear?
Type I–cup shape formed by afferent neurons
Type II– afferent neurons sit only at the base
What are the projections on the hair cells that sense movement of fluid (villi, cilia, microvili, sterocilia etc?)?
Stereocilia and kineocilia
What are the maculae?
Sensory part of the urticle and the sacule
The sacule connects what two structures?
The duct of the cochlea and the urticle (rest of the vestibule)
What is the structure that senses angular movement and is located in the ampulla of the semicircular duct?
Cristae Ampullaris
How is the cristae ampullaris oriented relative to their semicircular canals?
Perpendicular
What is the cupula of the cristae ampullaris?
Gelatinous protein-polysaccharide mass attached to the hair cells of each crista
Are there otoliths in the cupula?
No
What are the macula?
Sensory part of the utricle and the saccule
How are the macula of the utricle and the saccule oriented?
Saccule–vertically
Utricle–horizontally
Where are otoliths found? What is their function?
in the gel of the macules, aids in linear sensation
What are the three compartments of the chochlea that are separated by the cochlear duct?
Scala media
Scala vestibuli
Scala tympani
What are the lymphs that fill the scala media, vestibuli and tympani?
media -endolymph
vestibuli–perilymph
Tympani–perilymph
What is the helicotrema?
The cross over between the scala tympani and the vestibuil at the END of the chochlea
What is the order of the scala in the cochlea from top to bottom?
Vestibuli
Media
Tympani
What is the part of the chochlea that connects to the round window?
The scala tympani
What is the shape of the scala media? What the apex of the shape sits next to what structure?
Triangular, with apex sitting next to mediolus
What is the membrane the divides the scala vestibuli from the scala media?
Vestibular (Reissner’s) membrane
What is the structure that makes endolymph? Where is it found?
The stria vascularis, which sits in the outer portion of the scala media
The spiral organ of corti sits on what membrane?
The basilar membrane of the scala media
What type of junctions are on the vestibular membrane (which sits between the scala media and the scala vestibula)? What is its important here?
Tight junction, which separates the different ion gradients of the endo and perilymph
What is the stria vascualris? Where does it sit? What does it produce?
The structure on the base of the scala media that produces endolymph
What type of junctions are in the epithelium of the stria vascularis?
Tight junction
What membrane forms the roof of the scala media?
The vestibular membrane
The hair cells in the spiral organ of corti are embedded where?
In the tectorial membrane
Is there kinocilium in the organ of Corti?
No
How many sterocilia are present in the organ of Corti?
3-5
True or false: there are varying levels of the sterocilia in the organ of corti to aid in the sensation of movement
False–they are all symmetrical
What are phalangeal cells?
Support cells for the hair cells of the organ of corti
What forms the outer and inner tunnels that contain cortilymph?
The pillar cells
What forms the corticolymphatic space?
the summation of the apical cuticular plates from the digital processes of the outerphalangeal cells
What is the ionic compoistion of the cortilymph?
Same as perilymph–high is Na, low in K
What is the only attachment from the organ of Corti to the tectorial membrane?
The hair cells
What types of collagen are present in the tectorial membrane?
II, V, and IX
What is the medial attachment of the tectorial membrane?
The modiolus
How is sound perceived?
Oval window vibrates basal membrane, which vibrates tectorial membrane. This causes shear of the sterocilia and the hair cells in the organ of corti
What is the CN that is responsible for hearing?
CN VIII (vestibulocochlear)
What type of nerves connect the vestibular part of the ear to the brain? Where are these found?
Bipolar (ganglion)
Sit in the internal acoustic meatus
What type of ganglion is on the chochlea? Where is it located?
Spiral nerve, located on the modiolus
