Lecture 8: Ear

Question 1

Which branches of the external carotid artery supply the auricle

Answer 1

Posterior auricle artery

Superficial temporal artery

Question 2

What nerve innervates the skin of the auricle?

Answer 2

Great auricular nerve (C2, C3) 
Auricotemporal nerve (CN V3)

Question 3

What separates the external ear from the middle ear?

Answer 3

Tympanic cavity

Question 4

Tympanic membrane. What nerve supply’s its external surface and internal surface?

Answer 4

External surface: supplied by auriculotemporal nerve CN V3 plus a small auricular branch from vagus nerve
Internal surface supplied by glossopharyngeal nerve

Question 5

What is the name of an ear infection

Answer 5

Otis media

Question 6

Describe the location and function of the ossicles
malleus
Incus
Stapes

Answer 6

Attached to (moves with) tympanic membrane, articulates with INCUS- articulates with both malleus and stapes 
Stapes: its footplate (bottom of stirrup) fits into the OVAL window

Question 7

What is the branch of the facial nerve that crosses the MEDIAL surface of the MALLEUS?

Answer 7

Chorda tympani. It is the nerve that is responsible for the special sensory (taste) to anterior 2/3 of tongue and although it passes through the tympanic cavity it does not play a role in hearing or balance.

Question 8

What is the role of the tensor tympani and stapedius?

Answer 8

Tensor tympani tenses membrane to reduce oscillations, supplied by CNV3
Slide 23
Stapedius prevents excessive movement of stapes supplied by CN V11.

Question 9

Inner ear

What is the inner ear responsible for?

Answer 9

Reception of sound and maintenance of balance.
In petrous part of temporal bone (between middle ear and internal acoustic meatus).
-bony labyrinth= vestibule, 3x semicircular canals, cochlea which is lined with periosteum and contain perilymph
-membranous labyrinth (suspended within perilymph) = semicircular ducts, cochlear duct, 2x sacs (utricle and saccule)

Question 10

What is the auditory pathway?

Answer 10

Auditory cortex–medial geniculate body–inferior colliculus–etc?

Question 11

Vertigo. What is it?

What’s it caused by?

Answer 11

Illusion or perception of motion
-condition involving peripheral vestibular system or its CNS connections.
Caused by: migraine, vascular disease, brainstem tumours, viral infections, excessive endolymph

Question 12

Summary:

• primary sensory innervation of external ear by CN 3 and CN 10
• mucosa lining of tympanic cavity innervated by CN 9
• auditory ossicle transmit vibrations from tympanic membrane to inner ear.
• inner ear has hearing and vestibular functions
• deformation of cells within spiral organ stimulates impulses conducted by CN 8 to brain for sense of hearing
• maculae (saccule, utricle) innervated by vestibular portion of CN 8

Answer 12

Yehh done bitch