The Ear

Question 1

List the different layers of the Ear.

Answer 1

External Ear: Pinna and External Auditory Meatus (Air Transmission)

Middle Ear: Ossicles (Bone Conduction)

Internal Ear: Osseous Labyrinth and Membraneous Labyrinth (Fluid Conduction)

Question 2

Which way does the Tympanic Membrane tilt?

Answer 2

Forward and Down

Question 3

What do wrestlers develop before they have scarring and cauliflower ear?

Answer 3

Auricular Hematoma

Question 4

Describe the innervation and the various structures of the Tympanic Membrane.

Answer 4

Outer Epidermis –> GSA fibers from V and X

Inner Mucous Membrane –> GVA fibers from IX via the tympanic plexus

Umbo –> Central Concavity of the tympanic membrane

*** Anterior and Posterior Mallear Folds are formed by the inner mucous membrane on the borders of the pars flaccida (Chorda tympani nerve will go through these folds!)

Question 5

Where does the facial nerve travel in relation to the middle ear cavity?

Answer 5

Semicanal for Facial Nerve protrude into the middle ear cavity

*** It is NOT in the Middle Ear cavity

Internal Auditory Meatus –> Facial Canal (Geniculate Ganglion is located MEDIALLY and just above the promontory of the middle ear cavity) –> Exits the stylomastoid Foramen

Question 6

What happens when the auditory tube gets clogged?

Answer 6

Otitis Media (infection of the middle ear)

Accumulation of Fluid in the middle ear cavity

*** Will impair hearing transiently!

Question 7

Describe the different portions of the Auditory (Eustachian) Tube.

Answer 7

Bony Portion

Cartilaginous Portion (Torus Tubularis)

Question 8

List the three different ossicles.

Answer 8

1. Malleus –> Attaches to the Tympanic Membrane
2. Incus
3. Stapes

Question 9

What are the two muscles that are associated with the Middle Ear Cavity? Innervation? Function?

Answer 9

1. Tensor Tympani Muscle –> MANDIBULAR nerve of V (V3); Tightens the tympanic membrane and attenuates its vibrations
2. Stapedius Muscle –> FACIAL nerve; Pulls stapes out of the fenestra vestibuli. Protective mechanism to prevent excessive movement of the states due to loud noises

Question 10

Which attaches to the edge of the Petrous Portion of the Temporal Bone?

Answer 10

Tentorium Cerebelli

Question 11

Describe the relationship between the Facial, Cochlear, and Vestibular Nerves.

Answer 11

Cochlear Nerve goes ANTERIOR

Vestibular Nerve goes POSTERIOR

Question 12

Describe the Various Lesions to the Facial Nerve.

Answer 12

Question 13

Which artery will supply the inner ear?

Answer 13

Labyrinthine Artery (branch off of the AICA)

*** Arteriosclerosis of the labyrinthine artery may result in vertigo, nausea and other inner ear abnormalities

Question 14

What does the Cochlear and Vestibular Division innervate?

Answer 14

Cochlear division (VIIIc) innervates the organ of Corti (spiral organ) and conveys auditory information.

Vestibular division (VIIIv) innervates the maculae utricle and saccule, and the cristae ampullaris of the semicircular ducts.

Question 15

Answer 15

2.5 turns of the cochlear duct

Question 16

What is the structure at the center of the Cochlear Shell?

Answer 16

Modiolus (where the cochlear nerve goes into)

Spiral Lamina will “corkscrew” out of the Modiolus!