Cochlea - Membranous part

Question 1

List the structures of the membranous cochlea, including the 2 membranes. (this diagram is missing helicotrema)

Answer 1

• Scala media (cochlear duct)
• Scala vestibuli (vestibular canal)
• Scala tympani (tympanic canal)
• Helicotrema
• Reissner’s membrane
• Basilar membrane

Question 2

Where is the scala media (cochlear duct)?
What does it contain?
What is if filled with?

Answer 2

• Middle space of the membranous cochlea
• Contains the sensory organ of hearing
• Filled with endolymph fluid

Question 3

What are two parts of the Scala media (cochlear duct)?

Answer 3

• Lateral wall
• Base (floor)

Question 4

What is the lateral wall of the scala media (cochlear duct) made up of?

Answer 4

• Spiral ligament
• Stria vascularis

Question 5

What is the spiral ligament?

Answer 5

• Supportive thickening on the outer wall of the cochlea

Question 6

What is the stria vascularis

Answer 6

• Supplies blood and nutrients to the cochlea
• May manufacture endolymph

Question 7

What is important about the base (floor) of the scala media/cochlear duct?

Answer 7

• The basilar membrane forms the base/floor
• Contains the Organ of Corti

Question 8

Where/what is the scala vestibuli (vestibular canal)?
Where does it terminate/begin (depending on your viewpoint)
What is if filled with?

Answer 8

• Superior space above Reissner’s membrane (vestibular membrane)
• Terminates at the oval window
• Filled with perilymph

Question 9

Where/what is the scala tympani (tympanic canal)?
Where does it terminate?
What is if filled with?

Answer 9

• Inferior space below the basilar membrane
• Terminates at the round window
• Filled with perilymph

Question 10

Where is the helicotrema?

Answer 10

• Point of communication where the scala vestibuli and the scala tympani meet each other at the end of the scala media (at the apex of the cochlea)