Embryonic Development of the Ear

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Questions and Answers

What is auricular perichondritis?

Infection of the auricular perichondrium (correct)

Infection of the eardrum

Infection of the ear canal

Infection of the middle ear

What is the usual cause of auricular perichondritis?

Klebsiella pneumoniae

Escherichia coli

Staphylococcus aureus

Pseudomonas aeruginosa (correct)

What is affected in auricular perichondritis?

Cartilage

Muscle

Perichondrium (correct)

Skin

What type of infection is auricular perichondritis?

Bacterial Signup and view all the answers

What is the location of the infection in auricular perichondritis?

Auricle Signup and view all the answers

What type of epithelium lines the structure?

Squamous epithelium Signup and view all the answers

What is a possible complication of this structure?

Infection Signup and view all the answers

What symptom may arise when this structure gets infected?

Pain Signup and view all the answers

What is the treatment for this structure when it is asymptomatic?

Observation Signup and view all the answers

When is excision of this structure required?

When it is symptomatic Signup and view all the answers

What are the auricle and external auditory canal developed from?

1st and 2nd branchial arches Signup and view all the answers

What is the origin of the dorsal part of the 1st branchial cleft?

External auditory canal Signup and view all the answers

What happens to the ventral part of the 1st branchial cleft in normal development?

It normally disappears Signup and view all the answers

What is a possible consequence of the ventral part of the 1st branchial cleft not disappearing?

Preauricular sinus, cyst or collaural fistula Signup and view all the answers

How many tubercles contribute to the development of the auricle?

6 Signup and view all the answers

In which patients is auricular perichondritis not infrequently fatal?

Elderly diabetic patients Signup and view all the answers

Which group of patients is more likely to develop auricular perichondritis?

Patients with AIDS Signup and view all the answers

What is a common characteristic of patients who are susceptible to auricular perichondritis?

Old age Signup and view all the answers

Which of the following patients is at a higher risk of developing auricular perichondritis?

A patient with leukemia Signup and view all the answers

What is a common factor among patients who are susceptible to auricular perichondritis?

Immune system suppression Signup and view all the answers

What is a symptom of the acute stage of the disease?

Redness and swelling of the meatal skin Signup and view all the answers

What is a characteristic of the discharge in the chronic stage of the disease?

Purulent or serosanguinous Signup and view all the answers

Which of the following is NOT a symptom of the acute stage?

Deafness Signup and view all the answers

What is a symptom of the chronic stage of the disease?

Deafness Signup and view all the answers

What is a characteristic of the tympanic membrane in the acute stage of the disease?

Red and inflamed Signup and view all the answers

Study Notes

Development of the Auricle

The auricle is formed from six tubercles derived from the 1st and 2nd branchial arches.
The dorsal part of the 1st branchial cleft gives rise to the external auditory canal.
The ventral part of the 1st branchial cleft normally disappears, but can persist as a preauricular sinus, cyst, or collaural fistula.

Characteristics of the Auricle

The auricle is lined by squamous epithelium.
Infections of the auricle can lead to pain and pus discharge.
Excision is required only when the auricle is symptomatic.

Auricular Perichondritis

Definition: Infection of the auricular perichondrium, usually caused by Pseudomonas aeruginosa.
Acute stage: Characterized by redness and swelling of the meatal skin, pus in the meatus, and redness of the tympanic membrane.
Chronic stage: Characterized by deafness, purulent or serosanguinous discharge.
High-risk groups: Elderly diabetic patients, immuno-suppressed patients (e.g. those with AIDS, leukemia, on steroids or chemotherapy, or renal failure).

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Description

This quiz covers the development of the auricle and external auditory canal from the 1st and 2nd branchial arches. Learn about the formation of preauricular sinus, cyst or collaural fistula.