The ear

Question 1

What makes up the outer ear?

Answer 1

Outer ear: includes the auricle, external auditory meatus, and the tympanic membrane.

Question 2

What is the auricle?

Answer 2

Auricle: the AUDITORY CANAL. It is made of elastic cartilage and keratinized stratified squamous epithelium. It also has hair follicles.

Question 3

What is the external auditory meatus?

Answer 3

External auditory meatus: the outer third is made of elastic cartilage and the inner two thirds is bone. It is lined with stratified squamous epithelium and has glands that produce sweat and earwax.

Question 4

What is the tympanic membrane?

Answer 4

Tympanic membrane: EARDRUM. Separates the external auditory canal from the middle ear. It has vascularized connective tissue, which covered by a layer of skin. The internal surface is covered by simple cuboidal epithelium.

Question 5

What are the three regions of the middle ear?

Answer 5

The middle ear contains auditory ossicles, openings and muscles.

Question 6

That is the malleus?

Answer 6

Malleus: attaches to the tympanic membrane and hits the anvil.

Question 7

What is the incus (anvil)?

Answer 7

Incus: intermediate bone between the malleus and stapes.

Question 8

What is the stapes?

Answer 8

Stapes: is shaped like a stirrup and inserts into the oval window. When the stapes vibrates, the oval window also vibrates.

Question 9

What are the two openings found in the middle ear?

Answer 9

Openings – the oval window and round window

Question 10

What is the oval window?

Answer 10

Oval window: the stapes attaches to the membrane of the oval window, which opens into the scala vestibuli.

Question 11

What is the round window?

Answer 11

Round window: at the end of the scala tympani.

Question 12

What are the two muscles found in the middle ear?

Answer 12

Muscles – tensor tympani and stapedius.

Question 13

What is the tensor tympani?

Answer 13

Tensor tympani: inserts on the malleus.

Question 14

What is the stapedius?

Answer 14

Stapedius: inserts on the stapes.

Question 15

What are the functions of the tensor tympani and stapedius?

Answer 15

These muscles contract reflexively in response to loud sounds in order to damped the vibrations of the auditory ossicles. They are usually too late, but are useful in helping to ignore the sounds of one’s voice.

Question 16

What are the components of the inner ear?

Answer 16

Inner Ear – bony labyrinth, membranous labyrinth, vestibular organ and auditory organ.

Question 17

What is the bony labyrinth?

Answer 17

Bony labyrinth: canals and chambers in the petrous portion of the temporal bone. It contains sodium-rich lymph. It has four regions – semicircular canals, cochlea, scala vestibuli and scala tympani.

Question 18

What is the membranus labyrinth?

Answer 18

Membranous labyrinth: has potassium rich lymph. It also has structures embedded within the bony labrinth.

Question 19

What are the vestibular organs?

Answer 19

Vestibular organs: sensory structures that sense a chang ein position. They include saccule and utricle, as well as cristae.

Question 20

What are the maculae of the accule and utrile?

Answer 20

Maculae of accule and utrile: composed columnar cells and hair cells. The hair cells are in contact with nerve endings, and the otolithic membrane is a gelatinous memberane that overlies the epithelium. It has hair cells and causes sensory impulses via movements of the head and otolithic membrane.

Question 21

What are the cristae aumpullaris of the inner ear?

Answer 21

Cristae ampullaris of semicircular ducts: has columnar supporting cells and hair cells.

Question 22

What is the cupula?

Answer 22

Cupula: a gelatinous layer similar to the otolithic membarne, but there are no ostoliths. Movement causes forces between the semicircular canals and the contained fluid. Moving fluid displaces the cupula and causes the stereocilia to bend.

Question 23

What does the cochlear duct divide?

Answer 23

The cochlear duct divides the bony cochlea into scala vestibuli and tympani. The

Question 24

What form the roof and floor of the cochlear duct?

Answer 24

vestibular membrane forms the roofof the duct and the basilar membrane forms the floor of the duct.

Question 25

What forms the lateral aspect of the cochlear duct?

Answer 25

The stria vascularis forms the lateral aspect of the duct and creates lymph.

Question 26

Where is the organ of coti in the cochlear duct?

Answer 26

The organ of corti lies on the basilar membrane.