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Questions and Answers
What is the total length of the external auditory canal?
What is the total length of the external auditory canal?
What portion of the external auditory canal is cartilaginous?
What portion of the external auditory canal is cartilaginous?
Which section of the external auditory canal is primarily bony?
Which section of the external auditory canal is primarily bony?
Which anatomical structure allows communication between the parotid gland and the external auditory canal?
Which anatomical structure allows communication between the parotid gland and the external auditory canal?
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What is the correct division of the external auditory canal in terms of cartilaginous and bony sections?
What is the correct division of the external auditory canal in terms of cartilaginous and bony sections?
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Which statement about the Foramen of Huschke is true?
Which statement about the Foramen of Huschke is true?
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What fraction of the external auditory canal is bony?
What fraction of the external auditory canal is bony?
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What is the function of the Parotid Duct?
What is the function of the Parotid Duct?
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What is the narrowest portion of the external auditory canal?
What is the narrowest portion of the external auditory canal?
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At what location is the isthmus found in relation to the tympanic membrane?
At what location is the isthmus found in relation to the tympanic membrane?
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Which communication is not associated with the narrowest portion of the external auditory canal?
Which communication is not associated with the narrowest portion of the external auditory canal?
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What is the primary purpose of straightening the external auditory canal?
What is the primary purpose of straightening the external auditory canal?
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How is the external auditory canal typically straightened in adults?
How is the external auditory canal typically straightened in adults?
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What anatomical feature is the largest depression in the external ear?
What anatomical feature is the largest depression in the external ear?
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Which structure is present only in pars tensa and absent in pars flaccida?
Which structure is present only in pars tensa and absent in pars flaccida?
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What angle is the tympanic membrane placed at in relation to the canal?
What angle is the tympanic membrane placed at in relation to the canal?
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Which nerve supplies the roof and the anterior wall of the external auditory canal?
Which nerve supplies the roof and the anterior wall of the external auditory canal?
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What is the effective vibrating area of the tympanic membrane?
What is the effective vibrating area of the tympanic membrane?
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How is the side of the tympanic membrane identified based on the cone of light?
How is the side of the tympanic membrane identified based on the cone of light?
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What type of perforation involves all the quadrants of the pars tensa but leaves the annulus intact?
What type of perforation involves all the quadrants of the pars tensa but leaves the annulus intact?
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What is the length of the external auditory canal, and how is it divided into cartilaginous and bony parts?
What is the length of the external auditory canal, and how is it divided into cartilaginous and bony parts?
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What is the narrowest portion of the external auditory canal, and where is it located?
What is the narrowest portion of the external auditory canal, and where is it located?
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In the upper portion of the tympanic membrane, which layer is absent?
In the upper portion of the tympanic membrane, which layer is absent?
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Study Notes
External Auditory Canal Anatomy
- Length: 24mm
- Cartilaginous portion: 1/3 (8mm), lateral
- Bony portion: 2/3 (16mm), medial
- Important communication: Fissure of Santorini connects the parotid gland to the cartilaginous EAC.
Tympanic Membrane
- Effective vibrating area: 90mm²
- Cone of light: Used to determine the side of the tympanic membrane (e.g., 3 o'clock to 6 o'clock - Right).
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Pars tensa perforation types:
- Central: Involves more than one quadrant
- Large: Involves more than one quadrant
- Attic: Varies; doesn't necessarily include all quadrants
- Subtotal: Includes all quadrants but annulus stays intact.
External Ear Anatomy
- Narrowest portion (EAC): Isthmus, 6mm lateral to the tympanic membrane
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Important landmarks in EAC:
- Fissure of Santorini: Communication with the parotid gland
- Foramen of Huschke: Opening in bony portion, not cartilaginous
- Angles: Tympanic membrane is angled 45 degrees.
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Important Structures (EAC Anatomy):
- Cavum Concha: Largest depression in the external ear.
- Lempert endaural incision: An incision to prevent cartilage necrosis; incisura terminalis is the specific site.
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Tympanic membrane layers:
- Pars tensa: Has all layers
- Pars flaccida: Lacks the epithelial layer.
Additional Notes
- External auditory canal is S-shaped; needing to be straightened for visualization.
- Pulling the pinna outwards, upwards, backwards is used for visualization in adults.
- Pinna downwards, backwards in children
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Description
Test your understanding of the anatomy of the external ear, including the external auditory canal and tympanic membrane. The quiz covers important structures, measurements, and clinical relevance related to ear anatomy. Perfect for students in medical or health-related fields.
