Ear anatomy Flashcards

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1
Q

What is the function of the auricle?

A

Collect, focus, and direct sound down the funnel-shaped external acoustic meatus to the tympanic membrane

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2
Q

What antibodies have been identified in cerumen?

A

IgA, IgG and IgM

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3
Q

What is the predominant immunoglobulin in normal and inflamed ears?

A

IgG for both

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4
Q

What is the function of the Eustachian (auditory) tube?

A

Equalize pressure on both sides of the tympanic membrane

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5
Q

Name the 2 structures that attach to the malleus

A

Tympanic membrane and incus

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6
Q

Name the 3 components of the middle ear

A

Tympanic cavity, 3 auditory ossicles and tympanic membrane

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7
Q

What 2 structures attach to the stapes?

A

Vestibular window (in contact with perilymph fluid) and incus

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8
Q

Where does the tensor tympani muscle insert?

A

Malleus

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9
Q

What nerve innervates the tensor tympani muscle?

A

Branch of trigeminal nerve

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10
Q

Where does stapedius muscle insert?

A

Stapes

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11
Q

What nerve innervates the stapedius muscle?

A

Stapedial branch of facial nerve

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12
Q

Where do both the tensor tympani and stapedius muscles originate?

A

Tympanic bulla

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13
Q

Name the bony structure that houses the cochea

A

Promontory (where cochlear and vestibular windows are located)

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14
Q

Describe the 3 layers of the tympanic membrane and their origin

A

Inner epithelium: originates from pharyngeal pouch

Central layer: fibrous connective tissue of pharyngeal wall

Outer layer: stratified squamous epithelium derived from ectoderm of first pharyngeal groove

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15
Q

What is the stria mallearis?

A

Outline of the manibrium of malleus

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16
Q

Where should a myringotomy be performed?

A

Caudal ventral quadrant of TM (pars tensa)

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17
Q

Which direction does the manubrium of the malleus face?

A

C-shaped and concave aspect of the C points rostrally

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18
Q

Where and in what direction does tympanic membrane regenerate?

A

Radially from the umbo pars tensa

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19
Q

Name the clinical signs of Horner’s syndrome

A

Ptosis, pupillary miosis, prominent third eyelid, enopthalmia

20
Q

Where does the annular cartilage insert?

A

Within the bone of external acoustic meatus

21
Q

What are the 3 parts of the tympanic cavity?

A

Dorsal: smallest

Middle (aka tympanic cavity proper): adjacent to TM

Ventral: largest; tympanic bulla with septum bulla

22
Q

Know how to label this

A
23
Q

What are the 2 divisions of the septum bulla in cats?

A

Pars tympanica: small and dorsolateral

Pars endotympanica: large and ventromedial

24
Q

Name another dog breed reported to have PSOM other than CKCS?

A

Boxer, dachshund, and shih tzu

25
Q

Name the anatomical region where one inserts the ototscopic cone?

A

Antitragus

26
Q

What dog breed typically have excessive compound hair follicles in the horizontal ear canal?

A

Cocker spaniel dogs

27
Q

What dog breeds have simple hair follicles in the horizontal ear canals?

A

Greyhounds and mixed breed dogs

28
Q

What are simple coiled tubular glands that resemble apocrine sweat glands?

A

Ceruminous glands

29
Q

Ceruminous glands are composed of an inner secretory layer surrounded by ______ cells on a basement membrane

A

Myoepithelial cells

30
Q

What is the normal pH of ear canal epithelium in dogs?

A. 4.6-7.2

B. 6.0-7.4

C. 5.2-7.2

D. None of the above

A

A. 4.6-7.2 – Normal

B. 6.0-7.4 – Chronic otitis

C. 5.2-7.2 – Acute otitis

31
Q

What is the gas in the middle ear composed of?

A

Nitrogen 83%, oxygen 12%, carbon dioxide 4.7%

32
Q

What is an acoustic reflex?

A

When the ear is stimulated with a VERY loud sound, the stapedius muscle will contract to protect the middle ear from damaging level of noise

33
Q

Acoustic reflex is usually absent in patients with what disease?

A

Middle ear disease

34
Q

Blood supply to the ear comes from what 2 main arteries?

A

External carotid artery and vertebral arteries

35
Q

What is the largest artery to the ear?

A

Intermediate auricular branch

36
Q

Name the 4 nerves of the sensory innervation of the pinna

A

Trigeminal, facial, vagus, second cervical

37
Q

Which cartilage does NOT contribute to the formation of the externa ear?

A. Auricular cartilage

B. Annular cartilage

C. Scutiform cartilage

D. None of the above

A

C. Scutiform cartilage

38
Q

Know how to label this

A
39
Q

Can you label the inner and external ear structures of the dog?

A

You better!

40
Q

What nerve innervates the rostroauricular and caudoauricular muscles of the pinna?

A

Motor branches of the facial nerve

41
Q

What does the external ear consist of?

A

The auricle (pinna) and external acoustic meatus

42
Q

What does the middle ear consist of?

A

The ossicles, tympanic cavity, and bulla

43
Q

What does the inner ear consist of?

A

Cochlea and semicircular canals

44
Q

In horses, how is the junction between the cartilaginous and osseous portions of the external acoustic meatus grossly identified?

A

An abrupt change from pigmented to nonpigmented epithelium.

45
Q

Match the Tympanic membranes: Pig, Goat, Horse, Dog (ignore the bottom 2 images)

A

A, Horse. In the horse, the tympanic membrane (tympanum) is more round than other species. The manubrium of the malleus forms a very shallow arc and is centrally located in the tympanum.

B, Dog. The tympanum is oval to comma-shaped, and the manubrium of the malleus is C-shaped.

C, Pig. Similar to the dog, but the manubrium of the malleus is shorter and straighter.

D, Goat. Ruminants tend to have a more triangular-shaped tympanic membrane. In both pigs and ruminants, the manubrium of the malleus is more rostral and medial than in other species.

46
Q
A