Ear

Question 1

What are the structures of the external ear?

Answer 1

-auricle (pinna):
»tragus
»lobule (ear lobe)

-external acoustic meatus: ear canal

-tympanic membrane
»cone of light: reflection formed by malleus/umbo
»umbo: depression at the end of the malleus
»malleus: contoured ragion of tympanic membrane (ear ossicle)

**if pathology/rupture of tympanic membrane: region of darkness where it shouldn’t be

Question 2

What are the structures of the middle ear?

Answer 2

-tympanic cavity: space behind tympanic membrane (call this space the inner ear)
»pharyngotympanic tube (eustachian or auditory tube), connects tympanic cavity to nasopharynx

-auditory ossicles
»malleus: lays on tympanic membrane
»incus: junction between the malleus and the stapes (middle guy)
»stapes: anchors to the round window which moves fluid pressures in the ear

-muscles:
»stapedius: smaller muscle which is attached to the stapes
»tensor tympani: larger muscle that runs along the auditory tube and lands on the tympanic membrane/malleus

***these muscles serve as protection and will tense up when a loud sound wave enters the ear (prevent ear structures from moving too much during a loud sound)

Question 3

What are the structures of the inner ear?

Answer 3

-bony labyrinth: located in the petrous (very dense/thick) portion of the temporal bone and holds/protects the structures of the inner ear

-cochlea: auditory role, seashell shaped structure, responsible for translating sound waves, stapes will push on the fluid within the cochlea (mechanical process of stimulating receptors which will translate an action potential for CN8)

-vestibule of bony labyrinth: vestibular role (balance, equilibrium), football shaped cavity that holds the sacule and utricle

-semicircular canals: vestibular role (balance, equilibrium), anchor to the vestibule