Ear Anatomy and Physiology

Question 1

What are the three layers of the tympanic membrane?

Answer 1

The outer layer is continuous with the external auditory canal.
The middle layer is fibrous.
The inner layer is made up of respiratory epithelium (ciliated pseudo stratified columnar epithelium with goblet cells)

Question 2

What nerves run through the inner ear?

Answer 2

The facial, cochlear and vestibular nerves emerge from the inner ear and run through the internal acoustic meatus to the brainstem

Question 3

What are the three ossicles of the middle ear and what is their function?

Answer 3

They transmit sound from the tympanic membrane to the cochlear.
Malleus, incus and stapes.

Question 4

Via what structure does the middle ear connect with the mastoid?

Answer 4

Aditus

Question 5

What is cholesteatoma of the ear?

Answer 5

Keratinised squamous epithelium in the middle ear. Can be congenital or acquired.
Can present with foul smelling otorrhoea.

Question 6

What is the nerve supply to the ear?

Answer 6

Jacobsons Nerve - tympanic branch of glossopharyngeal nerve (CN IX)
Sensation to middle ear
Arnolds Nerve - Auricular branch of vagus nerve (CN X)
Sensation to posterior half of EAC
Facial nerve (CN VII)
Anterior half of EAC
Mandibular branch of trigeminal nerve (CN V3)
Pinna (upper half)
Greater Auricular Nerve (C2/3)
Pinna (lower half)

Question 7

How do ear structures help with balance?

Answer 7

Semi-circular canals detect head rotation.
Saccule detects linear acceleration in vertical plane
Utricle detects linear acceleration in horizontal plane