Anatomy of internal ear

Question 1

What are the two labyrinths?

Where are they located?

Answer 1

1- Bony labyrinth

2- Membranous labyrinth – lies within the bony labyrinth.

Question 2

What part of the temporal bone is the inner ear located within?

Answer 2

The petrous part of the temporal bone.

Question 3

What fluid fills the bony labrynth ?

Answer 3

perilymph

Question 4

What fluid fills the membranous labrinth ?

Answer 4

endolymph

Question 5

What does the bony labrinth consist of ?

Answer 5

Consists of a series of bony cavities within the petrous part of the temporal bone.

It is composed of the cochlea, vestibule and three semi-circular canals.

Question 6

What does the membranous labyrinth consist of ?

Answer 6

It is composed of the cochlea, vestibule and three semi-circular canals.

Question 7

What is the role of the cochlea ?

Answer 7

Hearing

Question 8

What is the role of the semicurcular canals?

Answer 8

Balance

Question 9

What are the three parts of the cochlear?

Answer 9

1- Scala vestibuli – Connected to the middle ear through the oval window. This contains perilymph.

2- Cochlear duct – This is filled with endolymph. This houses the organ of corti. The organ of corti is the mastermind of our hearing. It contains our hearing receptors/ hair cells.

3- Scala Tympani – Connected to the middle ear from the round window. Contains perilymph.

Question 10

In the cochlear, what is the most important part for hearing and what does it contain ?

Answer 10

Cochlear duct – This is filled with endolymph. This houses the organ of corti. The organ of corti is the mastermind of our hearing. It contains our hearing receptors/ hair cells.

Question 11

Explain how sound moves through the inner part of the ear.

Answer 11

When the foot of the stapes beats against the oval window - it transfers the vibrations over to the perilymph inside the scala vestibuli, forcing the fluid into motion. This motion transmits to the organ of Corti inside the cochlear duct.

The hearing receptors convert the vibrations into an electrical impulse. And the electrical impulse is sent to the brain via the auditory branch of the eight cranial nerve, and the perilymph inside the scala tympani is also set in motion. This makes the round window bulge back out towards the middle ear, relieving the pressure.

Question 12

What are the two parts of the vestublar aparatus ?

Answer 12

1- Three semi-circular canals – Shaped like Us. Filled with endolymph.

2- Utricle and saccule – Filled with endolymph. Both contain macula (balance receptors) which are balance receptors.