Anatomy and Physiology of Hearing Flashcards
What are the 3 parts of the ear?
External
Middle
Inner
What does the external ear consist of?
Pinna
External auditory ear canal
Where does the external ear end?
Tympanic membrane
What type of tissue is found at the pinna/auricle?
Stratified keratinized epithelium (skin)
Elastic cartilage
What is the function of the pinna?
To capture and transmit sound to the external acoustic meatus
What is outer curvature of the ear called?
Helix
What is the inner curvature of the ear called?
Antihelix
What is the hollow depression of the external ear called?
Concha of the auricle
Where does the external ear canal extend from to?
Deep part of the concha to the tympanic membrane
How long is the external auditory ear canal?
4cm
Where does the external ear canal end?
Tympanic membrane
Which bone is the tympanic membrane attached to?
Temporal
How can the middle ear be seen from the external ear?
Because the tympanic membrane is translucent
Which ossicle attaches to the tympanic membrane?
Handle of the malleus
What are 2nd most common causes of tympanic perforation?
Trauma
Infection
What is the treatment for foregin bodies in the ear?
Removal
What are the 3 layers of the tympanic membrane?
Outer layer is continuous with skin of EAC.
Middle fibrous layer
Inner layer of respiratory epithelium (ciliated columnar epithelium with goblet cells)
What is the diameter of the TM?
1cm
What is the thickness of the TM?
1/10th mm
What type of appearance should the TM have?
Shiny
Within which bone does the middle ear lie?
Temporal bone
Where does the middle ear expand from to?
Tympanic membrane to the lateral wall of the inner ear
What does the middle ear consist of?
Tympanic membrane
Ossicles
Eustachian tube
What are the 3 ossicles?
Malleus
Incus
Stapes
Which is the largest ossicle?
Malleus
What is the handle of the malleus in contact with ?
Tympanic membrane
What does the incus consist of?
Body
2 limbs
What is the smallest bone in the human body?
Stapes
Which ossicle connects to the oval window of the inner ear?
Stapes
Which epithelium lines the middle ear?
Respiratory epithelium
Stratified ciliated columnar non- keratinised epithelium
What connects the ear to the nose?
Eustachian tube
What are the 2 main portions of the inner ear?
Vestibular portion
Auditory portion
What does the vestibular portion control?
Concerned with balance
What does the auditory portion of the inner ear control?
Concerned with hearing
What is the nerve supply to the inner ear?
CN VIII
What is the organ of hearing?
Organ of corti
What does the scala tympani contain?
Perilymph
What does the scala media contain?
Endolymph
What does the scala vestibuli contain?
Perilymph
What are the 3 parts of the chochlea?
Scala tympani
Scala media
Scala vestibuli
Describe hearing?
Function of middle ear is transducing vibration into nervous impulses
Foot of stapes vibrates in oval window
Causes pressure wave through fluid in cochlear
This is detected by hair cells in organ of corti
Transmitted to brainstem (junction of pons and medulla) by CN VIII
What do semicircular canals pick up?
Rotation of the head
What is the function of the vestibulo-ocular reflex?
To allow you to fix your vision on an object even when your head is moving
What does the saccule do?
Detects linear acceleration in the vertical place
What does the utricle do?
Detects linear acceleration in the horizontal plane
Which nerve supplies the pinna?
CN V3
Which nerve supplies the anterior half of EAC?
Facial nerve CN VII
Which nerve supplies the sensation of the posterior half of EAC?
CN X (auricular branch)
Which nerve supplies sensation to the middle ear?
Tympanic branch of glossopharyngeal nerve
