EAR ANATOMY AND PHYSIOLOGY
What are the three main parts of the ear, and what structures do they include?
Outer ear: pinna, ear canal, tympanic membrane
Middle ear: malleus, incus, stapes, oval window, Eustachian tube
Inner ear: cochlea, semicircular canals, vestibule
What cranial nerve is responsible for carrying sound signals from the cochlea to the brain?
Cranial nerve VIII (the auditory or vestibulocochlear nerve)
Otorrhea after swimming is commonly caused by this condition.
Otitis externa
Name the three ossicles found in the middle ear?
Malleus, Incus, and Stapes
To avoid complications before removing a foreign body from the ear, you should always start with this essential step
inspecting the ear with an otoscope to assess the type, size, and location
What is the function of the tympanic membrane and ossicles in hearing?
The tympanic membrane vibrates in response to sound
Ossicles amplify and transmit vibrations to the inner ear via the oval window
What test compares air conduction to bone conduction using a tuning fork
Rinne test
Tragal tenderness is a classic sign of this condition
Otitis externa
What is the most common complication of untreated otitis media that can spread to the mastoid bone?
Mastoiditis
If a live insect is seen moving in the ear canal, this is the best first step before removal
immobilize it with mineral oil, alcohol, or lidocaine
What is the difference between the utricle and the saccule in sensing motion?
Utricle detects horizontal linear motion
Saccule detects vertical linear motion
In which type of hearing loss does the Weber test lateralize to the affected ear?
Conductive hearing loss
The most common bacterial cause of otitis externa.
Pseudomonas aeruginosa
Which bacteria are most commonly responsible for acute otitis media?
Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis.
This common but risky mistake when removing smooth or round objects from the ear can make things worse.
using forceps blindly, which can push the object deeper
How is mechanical sound converted into an electrical signal in the inner ear?
Sound waves move fluid in the cochlea
Hair cells in the Organ of Corti bend and generate electrical signals
What middle ear condition involves the buildup of skin debris and can cause chronic infection and hearing loss?
Cholesteatoma
A complication seen in diabetics with severe otorrhea and cranial nerve palsies.
malignant otitis externa
What are the three main function of the Eustachian tube?
1. Equalize air pressure between the middle ear and the outside atmosphere
2. Drainage of the nasopharynx
3. Ventilation
You must not irrigate the ear canal if this type of foreign body is suspected
a button battery or hygroscopic object (like beans)
This device is used when the auditory canal is too swollen to deliver ear drops.
ear wick