otitis media

Question 1

what is otitis media?

Answer 1

-infection of the middle ear

Question 2

what is the middle ear?

Answer 2

-the space that sits between the tympanic membrane and the lateral wall of the inner ear

Question 3

what is contained in the middle ear?

Answer 3

• auditory ossicles (malleus, incus, stapes)
• tensor tympani
• stapedius
• auditory tube/ Eustachian tube (anterior wall of middle ear)

Question 4

which bone does the middle ear lie within?

Answer 4

-temporal bone

Question 5

what is the main function of the middle ear?

Answer 5

-to transmit vibrations from the tympanic membrane to the inner ear via the auditory ossicles

Question 6

what can the middle ear be divided into?

Answer 6

2 parts:

• Tympanic cavity (contains auditory ossicles: malleus, incus and stapes)
• Epitympanic recess (a space superior to the tympanic cavity which lies next to mastoid air cells. The malleus and incus partially extend into it)

Question 7

describe the epitympanic recess

Answer 7

-a space superior to the tympanic cavity that lies beside the mastoid air cells. The malleus and incus partially extend upwards into the epitympanic recess

Question 8

what is the roof of the middle ear made up of?

Answer 8

-thin petrous portion of the temporal bone

Question 9

what is in the floor of the middle ear?

Answer 9

-internal jugular vein and thin layer of bone

Question 10

what is in the posterior wall of the middle ear?

Answer 10

• this is the mastoid wall

- it consists of a bony partition that separates the ear and the mastoid air cells

Question 11

what is on the anterior wall of the middle ear?

Answer 11

• there are two openings, one for the Eustachian tube and another for the tensor tympani muscle which attaches to the malleus
• this wall separates the middle ear from the internal carotid artery

Question 12

what is on the lateral wall of the middle ear?

Answer 12

• tympanic membrane

- lateral wall of epitympanic recess

Question 13

what is on the medial wall of the middle ear?

Answer 13

• oval and round windows
• facial canal containing facial nerve (innervates the stapedius muscle)
• promontory (bump formed by the first turn of the cochlear)

Question 14

what nerve innervates the stapedius muscle?

Answer 14

CNVII (facial nerve)

Question 15

what nerve innervates the tensor tympani?

Answer 15

CNV3 (mandibular division of trigeminal nerve) as the tensor tympani dulls noise during mastication

Question 16

roles of the tensor tympani and stapedius?

Answer 16

• they contract in response to loud noise, protecting the inner ear by inhibiting vibrations and dulling the noise
• this is also known as the acoustic reflex

Question 17

where are mastoid air cells loacted?

Answer 17

-in the posterior epitympanic recess within a cavity called the mastoid antrum

Question 18

role of the mastoid air cells?

Answer 18

• they act as a buffer system for air

- they release air into the tympanic cavity when pressure is too low

Question 19

what are the most common causes for otitis media?

Answer 19

Most common bacterial cause:

• streptococcus pneumoniae (most common)
• Haemophilus influenzae
• Moraxella catarrhalis
• staphylococcus aureus

Other:

• rhino sinusitus
• tonsilitis

Question 20

how does otitis media present?

Answer 20

• ear pain
• may have reduced hearing
• feeling generally unwell with a fever
• may have symptoms of URTI such as cough, coryzal symptoms and sore throat

Question 21

how may otitis media present on otoscopy?

Answer 21

-bulging red, inflamed looking ear drum

Question 22

what is the treatment for otitis media?

Answer 22

80% will resolve in 4 days without any treatment

1st line= amoxicillin
2nd line= erythromycin