Auditory Apparatus

Question 1

What are the three parts of the ear?

Answer 1

External Ear

Middle Ear

Internal Ear

Question 2

What makes up the middle ear?

Answer 2

• Epitympanic cavity
• Tympanic cavity proper
  
  • Contains auditory tube (eustachian tube)

Question 3

What are the parts of the External Ear?

Answer 3

Question 4

How long is the External Acoustic Meatus?

Answer 4

2-3 cm long

Question 5

Describe the structure of the external acoustic meatus

Answer 5

• Lateral one-third
  
  • S-shaped
  • Cartilaginous
• Medial two-thirds
  
  • Bony

Question 6

What secretes earwax? What is earwax also called?

Answer 6

Ceruminous Gland

Sebaceous Gland

Earwax = Cerumen

Question 7

What is the blood supply to the External Ear?

Answer 7

Superifcial Temporal Branch (of External Carotid A.)

Posterior Auricular Branch (of External Carotid A.)

Question 8

What is the main innervation of the External Ear?

Answer 8

Great Auricular Branch (of Cervical P|exus)

Auriculotemporal Branch (of CN V₃)

Question 9

Where does the Auditory Tube lead? What are its other names?

Answer 9

Leads to: Nasopharynx

Other names: Pharyngotympanic / Eustacian Tube

Question 10

What are the contents of the middle ear?

Answer 10

Auditory ossicles

Stapedius Muscle

Tensor Tympani Muscle

Chorda Tympani Nerve (Branch of CN VIII)

Tympanic Plexus of Nerves

Question 11

What are the parts of the middle ear?

Answer 11

Epitympanic cavity

Tympanic cavity proper

Question 12

Where is the Auditory Tube?

Answer 12

At the Anteromedial part of the Middle Ear

Question 13

What is at the superolateral part of the middle ear?

Answer 13

Mastoid Antrum (Cavity within bone)

Mastoid Air Cells

Question 14

What are the borders of the middle ear?

Answer 14

• Roof
  
  • Tegmen Tympani
  • Separates middle ear from dura mater of middle cranial fossa
• Medial Wall
  
  • Separes middle from inner ear
• Posterior Wall
  
  • Communicates with mastoid air cells
• Floor
  
  • Layer of bone separating tympanic cavity from Bulb of Internal Jugular Vein
• Anterior Wall
  
  • Separates Tympanic Cavity from Carotid Canal
• Lateral Wall
  
  • Tympanic Membrane
• Epitympanic Recess
  
  • Contains the uppermost extent of the Malleus and Incus

Question 15

What makes up the Tympanic Plexus? Where is it located?

Answer 15

Located on Promontory

Made up of:

• Lesser Petrosal Nerve
  
  • Branch of Glossopharyngeal Nerve
• Tympanic Branch
  
  • of Glossopharyngeal Nerve

Question 16

What are the two functional parts of the Vestibulocochlear Organ?

Answer 16

Organ of Balance: Vestibular Apparatus

Organ of Hearing: Cochlea

Question 17

What is the internal structure of the Vestibulocochlear Organ?

Answer 17

Bony Labyrinth

Membranous Labyrinth

Question 18

What makes up the Bony Labyrinth of the Vestibulocochlear Organ?

Answer 18

Otic Capsule. This is denser bone within petrous temporal bone.

Question 19

What does the Otic Capsule include?

Answer 19

Cochlea

Vestibule of bony labyrinth

Semi-circular canals

Question 20

What does the Membranous Labyrinth include?

Answer 20

Sacs and Ducts

Endolymph

Question 21

What are the two types of fluid within the vestibulocochlear organ?

Answer 21

Perilymph - surrounds the membranous labyrinth

Endolymph - within the membramous labyrinth

Question 22

What supports the Membranous Labyrinth?

Answer 22

Spiral Ligament

Delicate filaments that traverse perilymph

Question 23

What are the two parts of the membranous labyrinth?

Answer 23

Vestibular Labyrinth

• Utricle
• Saccule
• Ampulae
• Semi-circular ducts

Cochlear Labyrinth (Cochlear Duct)

• Spiral tube

Question 24

What is the structure of the Cochlear?

Answer 24

Cochlear Duct (Spiral Tube)

• Suspended by spiral ligament
• Houses the Spiral organ (of Corti)