Ear

Question 1

Three layers of the tympanic membrane:

1. Outer
2. Middle
3. Innermost

Answer 1

Outer: stratified squamous epithelium skin)
Middle: connective tissue
Innermost: continuous with mucosa of middle ear (ciliated columnar)

Question 2

Structure and make-up of auditory tube:

• Ant/post make up?
• Length
• Relationship b/t cartilage and bony portions
• Location of membranous portion

Answer 2

-Anterior 2/3: cartilaginous & Posterior 1/3: bony (osseous)
– ~36 mm long
– Cartilaginous & bony portions meet at narrow isthmus
• Bony portion of tube opens at base of skull • Only superior & Medial walls cartilaginous •
-Inferior & Lateral walls membranous

Question 3

Tegman Tympani:

1. relationship to tegman tympani
2. serves as a “cover” for what?
3. Formed by what bone (be specific)

Answer 3

superior border of middle ear cavity
Covers the epitympanic recess
Formed by thin plate of temporal bone

Question 4

What is the Tympanic Sulcus?

Answer 4

bony ring that secures the lower 5/6 of tympanic membrane

Question 5

Describe the Notch of Rivinus

Answer 5

Upper 1/6 of the tympanic membrane that is secured by ant/post malleolar folds

Question 6

Relationship b/t oval window and ossicles

Answer 6

Receives the base of the stapes (acts as a kind of piston)

Question 7

Another name for the oval window?

Answer 7

Fenstra Vestibuli

Question 8

Describe the round window

Answer 8

membrane covered structure inferior to oval window on medial wall

Question 9

Another name for the round window

Answer 9

Fenestra Chochlea

Question 10

Name the 6 structures on the medial wall of the tympanic cavity

Answer 10

Promontory 
Fenstra vestibuli = oval window
Fenestra Cochlea = round window 
Facial canal prominence –
Lateral semicircular canal prominence
Tendon of the tensor tympani m.

Question 11

Name for the anterior wall of the tympanic cavity is ______?

Answer 11

Carotid Wall

Question 12

What is/are the major landmarks (structures) in the carotid wall?

Answer 12

1. Auditory Tube

2. Semicanal for tensor tympani

Question 13

What is/are the major landmarks (structures) on the posterior wall of the middle ear?

Answer 13

1. Pyramidal Eminence= hollow projection of bone
   – Serves as origin of stapedius m.
2. Aditus ad antrum= entrance to tympanic antrum
   – Leads to post./infr. into mastoid air cells

Question 14

Describe the structure, location, action and innervation of the Tensor Tympani m.

Answer 14

Contained in bony semicanal – Superior to auditory tube
• Runs posterior thru canal& then bends laterally
• Inserts on to handle of malleus
• Tenses tympanic membrane by drawing it medially
• Innervated by CN V3

Question 15

What makes the stapedius m unique in the body?

Answer 15

Smallest striated skeletal muscle in the body (~1mm)

Question 16

Describe the origin, insertion, action, and innervation of the stapedius m.

Answer 16

Arises from cavity inside pyramidal eminence
• Inserts into neck of stapes
• Pulls head of stapes posteriorly
• Innervated by CN VII

Question 17

What is the pathway of the Chorda Tympani

Answer 17

Branches in facial canal
Enters ear cavity through posterior iter chordae- crosses m. tympanic membrane
Passes between handle of malleus & incus
Exits thru anterior iter chordae –> tongue

Question 18

Describe the Autonomic innervation of the ear

Answer 18

Tympanic plexus- covers promontory
Tympanic nerve (branch of CN IX (p-symp))
Cartoticotympanic nn (symp from carotid plexus)
Supplies mucosal lining of promontory, mastoid air cells and auditory tube

Question 19

What ate the branches of CN VII that can be found in the ear?

Answer 19

1. Chorda Tympani

2. Greater petrosal n.

Question 20

What is the pathway of the lesser petrosal n.?

Answer 20

IX –> tympanic nerve –> tympanic plexus –> lesser petrosal –> carries p-symp fibers –> exits via hiatus of l. petrosal (now in middle cranial) –> out thru ovale –> otic ganglion (synapse) –> postganglionic fibers to parotid gland

Question 21

What is the parasympathetic and sensory innervation to the middle ear?

Answer 21

Tympanic nerve (Jacobson) of CN IX

Question 22

What is the function of the auricle?

Answer 22

Directs sound to the external acoustic meatus

Question 23

What is the function f the External Acoustic Meatus?

Answer 23

Directs sound to the tympanic membrane

Question 24

What part of the external acoustic meatus is cartilaginous?

Answer 24

Distal 1/3

Question 25

What part of the external acoustic meatus is boney? And which bone is it?

Answer 25

Proximal 2/3; Temporal bone