Ear Flashcards
List the two main components of the external ear and state the function of each.
(air on one side air on the other)
Auricle (pinna) - traps sound waves
External acoustic meatus - air filled passageway that channels sound vibrations from the auricle to the tympanic membrane
Explain the purpose of ceruminous glands.
Ceruminous glands produce wax (cerumen) which act as an insect repellant and keeps the tympanic membrane soft and pliable.
Sketch a pinna and label its parts
pg. 435
List the components of the middle ear and state the purpose of each.
(air on one side, perilymph on the other)
Tympanic Membrane - “ear drum” vibrates in response to sounds waves in the atmosphere
- covered by thin skin and c.t. proper
Tympanic Cavity - air filled cavity of the middle ear. Transversed by 3 auditory ossicles and has 6 named walls : membranous wall (medial), labyrinthine wall (lateral/ contains vestibular and cochlear window) , tegmental wall (superior), jugular wall (inferior) , mastoid wall (posterior), carotid wall (anterior)
- cochlear window is covered by secondary tympanic membrane which is a relief valve for internal ear/ allows perilymph to move
Auditory Tube - passageway connecting the tympanic cavity to the nasal part of the pharynx; allows equalization of air pressure on both sides of tympanic membrane by allowing air into or out of the otherwise closed tympanic cavity in response to changing barometric pressure
- lined by mucous membrane
Auditory Ossicles - malleus, incus, and stapes (smallest bone in body); transmit sound vibrations from the tympanic membrane across tympanic cavity into the internal ear
- covered by mucosa to keep from drying
List the auditory ossicles in the order that sound vibrations pass through them and name the three joints involved.
Malleus –> Incus (@ incudomallear jt.) –> Stapes ( @ incudostapedial jt.) –> Vestibular window (by tympanostapedial syndesmosis - FIBROUS JOINT)
- as the stapes moves into the vestibular window like a plunger, it creates waves into perilymph
State which direction air moves in the auditory tube in response to changing barometric pressure.
@ sea level P outside of tympanic membrane = pressure inside of tympanic membrane
@ mountain top (high altitude) P outside of tympanic membrane < than P inside of tympanic membrane (tympanic membrane pushed out)
- solution: push air out of auditory tube
Descending from mountain top: P outside of tympanic membrane > than P inside of tympanic membrane (tympanic membrane pushed in)
- solution: valsalva manouver (push air into tympanic cavity)
https://www.youtube.com/watch?v=PCpRyp5EUFo
List the muscles associated with the auditory ossicles and state their function.
- Stapedius m. - inserts onto stapes
- Tensor tympani m. - inserts onto malleus
- their contraction dampens the vibrations of excessive amplitude and serves to protect the delicate structures of the internal ear from damage
Define osseous labyrinth, divide it into its three major components, and state which parts of the membranous labyrinth (internal ear) each one contains.
Osseous Labyrinth: channels in petrous part of temporal bone that surround various components of the internal ear
- Cochlea:
- contains cochlear duct of internal ear
. spirals 2.5 times
. contains spiral organ - Vestibule:
- contains utricle and saccule of internal ear - Osseous Semicircular Canals (anterior, posterior, lateral) :
- semicircular ducts
- osseous labyrinth contains perilymph (CSF) which suspends the internal (membranous labyrinth) ear
Define membranous labyrinth, divide it into its three major components, and indicate the sensation with which each one is associated.
(perilymph on one side, air on the other)
Membranous Labyrinth: internal ear
- Cochlear Duct
- hearing - Utricle and Saccule
- detection of straight line motion - Semicircular Ducts
- detections of turning and twisting movements
State the location of perilymph and endolymph.
Perilymph: osseous labyrinth
Endolymph: outer wall of cochlear duct in the stria vascularis (membranous labyrinth)
Explain how gravity and inertial forces interact with the maculae in the saccule and utricle to cause impulses that allow us to detect linear acceleration.
Utricle
Utricle: horizontal plane
- maculae in the statoconial membrane of the utricle are horizontally oriented.
- the hair cells (maculae) stimulate impulses when they are bent
- due to the orientation of the maculae and hair cells processes (on a horizontal plane), the utricle responds to horizontal movement (front/back and left/right)
Explain how gravity and inertial forces interact with the maculae in the saccule and utricle to cause impulses that allow us to detect linear acceleration.
Saccule
Saccule: sagittal plane
- maculae in the statoconial membrane of the saccule are sagitally oriented
- the hair cells (maculae) stimulate impulses when they are bent
- due to the orientation of the maculae and hair cell processes, the saccule responds to sagittal movement (front/back and forward/backward0
Explain how endolymph in the semicircular ducts interacts with the cupula of a crista ampullaris to cause impulses that allow us to detect angular (turning, twisting) movements.
When turning or twisting movements of the head and neck occur, the endolymph within the semicircular ducts presses again the cupulae and bends the cilia of the hair cells. This initiates impulses which are sent to the brain through the bipolar cells of the vestibular nerve and interpreted as turning/twisting movements.
List, in order, all of the items that sound vibrations pass through to reach the hair cells in the spiral organ.
???
https://www.youtube.com/watch?v=PeTriGTENoc
- Air
- External Acoustic Meatus
- Tympanic Membrane (3 layers)
- Malleus, synovial joint
- Incus, synovial joint
- Stapes, syndesmosis
- Perilymph
- Vestibular Membrane
- Endolymph
- Hair Cells (embedded in tectorial membrane)
- Spiral Organ
Differentiate sensory vs. conductive deafness.
Sensory Deafness:
problems within the cochlear duct, within the pathways transmitting impulses to the auditory cortex of the temporal lobe, or within the auditory centers of the temporal lobes
- reduced ability to hear sounds of certain frequencies
Conductive Deafness:
interference in the transmission of sound waves from the air through the tympanic membrane and auditory ossicles
- impairs hearing at all sound frequencies
https: //www.youtube.com/watch?v=Y3tWqznAP8I
