NERVOUS SYSTEM Session 7 Flashcards
What are three division of the ear?
- Outer , Middle and Inner
What does the Outer ear consist of ?
- Consists of the pinna and the auditory canal
Where is the Middle of the ear classified as ?
- begins at the tympanic membrane ( eardrum ) and ends at a bony wall containing two small openings covered by membranes
What are the two small openings in the middle ear known as ?
- Oval window and round window
What three small bones found here ( ossicles )
- Malleus ( hammer , touches the tympanic membrane )
- Incus ( anvil )
- Stapes ( stirrup , which touches the oval window )
What connects the middle ear to the nasopharynx ?
- the auditory tube
What are the three areas of the inner ear and what do each of them do ?
- The semicircular canals and vestibule both handle equilibrium and the cochlea handles hearing
How does the auditory pathway work to the brain ?
- sound waves strike the tympanic membrane , which causes vibrations of the malleus , incus and then the stapes
- the ossicles actually amplify the vibrations and then the stapes strikes the oval window causing it to vibrate which then passes the pressure to the fluid within the cochlea
- Which then causes the basilar membrane to move up and down , bending the sterocillia of the hair cells embedded in the tectorial membrane .
- Lastly Nerve signals now begin in the cochlear nerve and travel to the auditory cortex in the temporal lobe , where they are interpreted as sound .
What are the three different canals of the cochlea ?
- Vestibular , Cochlear , Tympanic
What is the Spiral organ (Organ of Corti) ?
- The sense organ of hearing
How are low and high pitches interpreted in the spiral organ ?
- The tip of the spiral organ respond to low pitches and the base respond to higher pitches
How is the volumed effect the activity in the cochlea ?
- If it is louder , it causes the fluid in the vestibular canal to exert more pressure and the basilar membrane to vibrate to a greater extent
What is the sense of equilibrium ?
- It is the position in space which is transmitted by vestibular nerve taking information from the semicircular canals , saccule and utricle , which then takes signals to the Brian stem and cerebellum
How is rotational equilibrium handled?
- By the mechanoreceptors in the semicircular canals.
What is the ampulla and what does it contain ?
- it is the base and it contains hair cells , whose steroecillia is embedded within the cupula
How does the rotational equilibrium pathway work ?
- As fluid ( endolymph ) within a semicircular canal flows over and displaces a cupola , the stereocilia of the hair cells bend , then the vestibular nerve carries signals generated here to the brain.
- Then appropriate motor output to various skeletal muscles corrects the body position in space as needed
What does the gravitational equilibrium include ?
- movement of head relative to gravity
what are the two membrane races located near the semicircular canals called and what do each of the deal with ?
- Utricle : deals with the vertical changes
- Saccule : deals with the horizontal changes
Where are the stereocilia embedded of Utricle and Saccule ?
- In the otolithic membrane
What is a Otoliths ?
- they are calcium carbonate granules that rest on the otolithic membrane
How does the resting position of the Otoliths vary in relation to movement ?
- When the body is still , the otoliths rest on the otolithic membrane above the hair cells
- When the body moves in the horizontal and vertical planes the otoliths are displaced
What is the increase and decrease in the vestibular nerve caused by ?
- When the stereocilia bend toward the largest steroecilium ( kinocilium ) nerve impulses increases in the vestibular nerve
- When the sterocilia move away from the kinocilium , nerve impulse decreases
