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Flashcards in ENT Ear Anatomy Deck (30):
1

What are the 3 parts of the Ear?

External Ear
Middle Ear
Inner Ear

2

What bone is the Inner 2/3 of the Ear Canal (EAM) embedded in?

Temporal Bone
Has Squamous and Petrous parts

3

What are the functions of the ear?

Hearing
Balance

4

What anatomical structures does the Temporal Bone contain?

Middle Ear Cavity
Inner Ear (Organs of Hearing and Balance)

CN VII
CN VIII

5

What is the thinnest part of the skull?

Pterion

H-Shaped Suture of the Temporal, Frontal, Parietal and Sphenoid Bones.

6

What structures is the Ear Canal made up of?

1/3 Cartilage (Avascular so recieves blood supply from skin)

2/3 Bone (Temporal)

7

The Ear Canal is horizontally straight. True/False?

False!
Has a loose S curve to it so needs to be pulled at auricle to straighten it out

8

Which glands secrete ear wax?

Ceruminous Glands

9

What is the main nerve supply to the auricle?

Cervical Spinal Nerves 2 and 3

Some innervation with CN V3 also present

10

What is the nerve supply to the External Tympanic Membrane and EAM?

CN X (Inferior Parts of EAM and 1/3 of EXTERNAL Surface of Tympanic Membrane)

Auriculotemporal Branch of CN V3 (Superior Parts of EAM as well as the 2/3 of EXTERNAL Surface of the Tympanic Membrane.

Also some CN VII Involvement for Sensation.

11

What is the nerve supply to the INTERNAL surface of the Tympanic Membrane?

CN IX

12

What is the Lymphatic Drainage of the Auricle?

Lateral Surface of the Superior Half drains into the Parotid Lymph Nodes

Cranial Surface of the Superior Half drains into the Mastoid and Deep Cervical Lymph Nodes

Remainder of the Auricle/Pinna drains into the Superficial Cervical Lymph Nodes

13

What are other innervations of CN IX?

Middle Ear Cavity
Eustachian Tube
Nasopharynx
Posterior 1/3 of Tongue
Parotid Glands
Tonsils

14

What are the 2 muscles of the Ossicles?

Stapedius
Tensor Tympani

15

What are the main structures of the Middle Ear Cavity?

Tympanic Membrane
Ossicles
Oval Window
Round Window
Eustachian Tube
Epitympanic Recess (source of Mastoiditis)
Aditus
Chorda Tympani of CN VII
Internal Carotid Artery at Anterior Wall

16

What are the functions of the Eustachian Tube?

Equalise Air Pressure in the Middle Ears
Ventilate Middle Ear Mucosa

Source of Infection Tracking into Middle Ear

17

How does Chorda Tympani nerve arise?

CN VII will travel in the IAM, until it reaches the Temporal Bone where it splits into the Chorda Tympani Nerve and CN VII

Chorda Tympani branches off whilst CN VII continues through IAM

18

What are the Chorda Tympani innervations?

Taste Sensation to Taste Buds on Anterior 2/3 of Tongue

Parasympathetic Innervation to Submandibular and Sublingual Salivary Glands but NOT the Parotid Salivary Gland

19

What are the CN VII innervations?

Motor Innervation to the Muscles of Facial Expression

20

Which part of the Temporal Bone is the Inner Ear found in?

Petrous Part

21

What are the 2 branches of CN VIII?

Vestibular Nerve
Cochlear Nerve

22

What is the name given to the cochlear and vestibular apparatus?

Otic Capsule

23

What fluid does the bony labyrinth contain?

Perilymph

24

What fluid is contained within the Membranous Labyrinth?

Endolymph

25

What is the tip of the Cochlea called?

What sound frequencies does it detect?

Cupula (Apex)

Low Frequencies

26

What are the Ampullae?

End-Dilations of the Semicircular Canals where the Balancing Sensory Cells are held

27

What are the Maculae?

Regions containing clusters of hair cells that sense Endolymph Movement

28

What do the Semicircular Canals detect?

Changes in the Velocity of Angular Motion.

29

What changes in movement does the Saccule detect?

Vertical Movement Change

30

What changes in movement does the Utricle detect?

Horizontal Movement Change