Anatomy + physiology of the Ear

Question 1

What bone contains the entire ear and what are the two parts of it?

Answer 1

Temporal bone

Squamous part, petrous part (thicker bone)

Question 2

What are the structures at the beginning and the end of the ear canal?

Answer 2

External acoustic meatus to tympanic membrane

Question 3

What nerves supply most of the sensation to the external ear?

Answer 3

Helix/lobe = C2, 3

Ear canal = CNV3, CNX
(mandibular, vagus)

Tympanic membrane = CNX, CNV3 (upper 2/3rds)

Question 4

Where does the ear drain lymph to?

Answer 4

Deep cervical lymph nodes (in carotid sheath)

Question 5

What structures are contained within the middle ear (tympanic cavity)?

Answer 5

Ossicles/bones: malleus, incus, stapes
Muscles: stapedius, tensor tympani
Eustachian tube

Question 6

Where does the eustachian tube travel? What is its nerve supply?

Answer 6

Middle ear to nasopharynx

Glossopharyngeal nerve (CNIX)

Question 7

What nerves supply the muscles within the ear?

Answer 7

Stapedius = facial (CNVII)

Tensor tympani = mandibular (CNV3)

Question 8

What is the chorda tympani?

Answer 8

Branch of facial nerve

Travels through middle ear and continues on to supply taste to the anterior 2/3rds of tongue

Question 9

What is used to interpret vertical, horizontal or forward/back/sideways movement in the inner ear?

Answer 9

Vertical = saccule
Horizontal = utricle 

Other = semilunar canals (superior, posterior, lateral)

Question 10

What substances/structures are contained within the semilunar canals and the cochlea?

Answer 10

Perilymph (composition similar to ECF
Membrane
Endolymph (encased within membrane - similar composition to ICF)

Question 11

What is the function of the round window?

Answer 11

To dampen vibrations after signals sent to brain