Ear

Which cranial nerves supply sensory (SA) innervation to the skin of the concha region?

CN VII, IX, and X

Name the 4 cranial nerves that are involved in the sensory innervation of the ear.

CN V (V3-auriculotemporal), VII, IX, and X

Medially, the external auditory meatus leads to what structure?

tympanic membrane (ear drum)

What space is medial to the tympanic membrane?

middle ear cavity

Name the 3 bony ossicles of the middle ear cavity.

1. malleus

2. incus

3. stapes

Which bony ossicle has a portion which overlies the oval window?

Stapes - its footplate lies over the membrane of the oval window

Describe in 3 steps, how sound waves are converted into "sound" perceived by the brain.

1. Sound waves cause tympanic membrane to move, leading to movement of the 3 ossicles

2. Movement of the stapes causes fluid current change in the cochlea

3. Fluid current changes cause specialized hair cells (in the spiral organ of Corti) to move and trigger nerve impulses to the brain (via CN VIII) which are interpreted as sound

Name the 6 boundaries of the middle ear cavity.

1. Lateral wall

2. Medial wall

3. Anterior wall

4. Posterior wall

5. roof

6. floor

Which structure forms the lateral wall and what nerve is related to this wall?

- formed by tympanic membrane (ear drum)

- chorda tympani of CN VII is related to it

Which muscle attaches to the handle of the malleus and what is its function?

- "Tensor tympani" muscle attaches to handle of malleus

- Acts to dampen vibration of the malleus

What plexus lies on the medial wall and which nerve does it give rise to superiorly?

- Tympanic plexus

- Gives rise superiorly to lesser petrosal nerve

What is the function of the round window?

relieve pressure in the inner ear caused by the activity of the stapes

Onto which wall of the middle ear cavity does the auditory tube open?

Anterior wall

Which canal is located in the posterior wall of the middle ear cavity and what occupies it?

Facial canal occupied by the facial nerve

What is the inferior termination of the facial canal?

the stylomastoid foramen

What muscle attaches to the stapes and what is its function?

- Stapedius

- acts to dampen vibrations of the stapes

Name the two main structures of the inner ear and what do they do?

1. vestibular labyrinth (semicircular canal system) - maintence of balance

2. cochlear labyrinth- reception of sound

Which part of the temporal bone contains the 2 main structures of the inner ear?

Petrous part of temporal bone

1. The region of the ear is important for understanding which special senses?

one special sensory (SS) pathway for taste to anterior 2/3rds of the tongue (via chorda tympani)

How many parasympathetic pathways are coursing through the middle ear cavity?

Two

Which nerves related to the middle ear are involved in the pathway to the otic ganglion?

1. Tympanic nerve

2. Lesser petrosal nerve (parotid gland)

Which nerve coursing through the middle ear brings VE-para/pre fibers to the submandibular ganglion?

Chorda tympani

Which nerve coursing through the middle ear cavity is involved in pathway for taste to the anterior 2/3rd of the tongue?

Chorda tympani

Summary Slide

The ear region is important for understanding:

1. hearing and balance

2. two parasympathetic pathways to 3 salivary glands

- to the otic ganglion via tympanic nerve and lesser petrosal nerve (parotid gland)

- to the submandibular ganglion via chorda tympani (for submandibular & sublingual glands)

3. one special sensory (SS) pathway for taste to

anterior 2/3rds of the tongue (via chorda tympani)