Hearing and Balance and Olfactions

Pina

outside of ear

Ear inside tell me how to get in

external ear, inner ear, middle ear

Hearing workflow

sound goes into the internal ear, tap on the tympanic membrane, vibrations cause vibration of ossicles, then the inner ear vibrates sending signals to VIII (vestibulocochlear)

nasopharynx is connected to middle ear via pharyngotyympanic tube.

External ear made up of what?

2/3 cartilage 1/3 skin attacahed to bone

3 Ossicles

Malleus attached to incus attached to stapes

Ear infections

more horizontal pharygotympanic tube causing infected ear and reduced hearing and buldging tympanic membrane

Oval window

transition from middle ear to inner ear

Cochlea

3 fluid filled chambers: Scala media, scala vestibuli, scala tympani (vestibuli and typani continous with eachother).

coclear duct has endolymph in it with perilymph in the sacala vestibuli and scala tympani surrounding it

Sounds

Treble closest to oval window, mid, bass furthest.

Walk me through how sound is heard from oval window

Vibrations from oval window cause perilymph in the scala vestibuli to shake, this causes the cochlear duct to shake as well. which then in turn leads to the tectorial membrane shaking. Bending of the hair cells in cilia cause sound. then it is released through round window.

Conductive vs Sensorineural hearing loss

conductive is mechanical disruption (unilateral), bilateral neural

Balance 3 main organs and which cranial nerve

Utricle (horizontal) and Saccule (vertical)

Semi-circular canals (rotational acceleration)-anterior posterior lateral

CN VIII

Othalithic Organs

Linear acceleration (utricle and saccule)

using othalithic membrane bending the hair cells

Different membranes

Tectorial - cochlea

Othalithic- Othalithic organs (utricle and saccule)

Cupula- semicircular canals

Semicircular canals

Lateral, anterior, posterior

crista has hair cells that are bent by the cupula

Nasal Cavity regions

Olfactory region and respiratory region

You only smell in the top portion of your nose (where CN I comes in)

Olfaction

chemoreceptors, olfactory epithelium (part of nerve) synapse at olfactory bulb, then go to olfactory tract to the cortex

Extends through the cribriform plate of the ethmoid bone innervates mucosa and doesn’t go through the thalamus.