Middle Ear

Question 1

What portion of the Eustachian tube is surrounded by cartilage? Bone?

Answer 1

Superior 1/3 is bone

Inferior 2/3 is cartilage

Question 2

Which nerve runs next to the middle ear cavity?

Answer 2

The facial nerve runs next to the middle ear cavity.

Question 3

What is the promontory? What is its function?

Answer 3

The promontory is a rounded prominence formed by the lateral projection of the basal turn of the cochlea. Its function is to protect the oval and round windows as it directly faces the middle ear cavity.

Question 4

What vein runs next to the inferior wall of the middle ear cavity? What type of tumor is common to destroy this wall?

Answer 4

Jugular vein

Glomus jugulare tumor

Question 5

The Eustachian tube in children is roughly at what angle? In adults?

Answer 5

Children: horizontal
Adults: @ 45 degrees

Question 6

What are the names of the ossicles?

Answer 6

Malleus, incus, and stapes

Question 7

The middle ear bones solve what major problem in the transduction of sound?

Answer 7

Impedance mismatch

Question 8

What are the three mechanisms by which the ossicles improve sound transduction?

Answer 8

Change in surface area
Lever action
Buckling of TM

Question 9

The tympanic membrane moves in what direction?

Answer 9

Buckles medially, not piston-like motion

Question 10

Which of the ossicles is the weakest and most likely to break?

Answer 10

Incus