Ear anatomy

How does the ear mediate our hearing 

By transformation of sound vibrations into neural signals 

How does the ear regulate our balance 

It relates positional information about our head 

What are the 3 sections of the ear 

• External 

• Middle 

• Inner 

What is the external ear composed of (2)

• Auricle 

• external auditory canal 

What is the auricle composed of ( material)

Elastic cartilage covered by skin

What is the function of the external auditory canal

Collect vibrations and waves from the auricle to the tympanic membrane or eardrum

also separates external and middle of ear

What is the middle ear/ tympanic cavity filled with

An air filled cavity 

What is the function of the middle ear/tympanic cavity 

Transmit vibrations from the tympanic membrane or eardrum into the inner ear 

Why does the tympanic membrane have a concave structure

Malleus’ (bone) has a handle on the tympanic membrane which pulls it inward and that keeps it concave 

When illuminated via otoscope, what does the concavity of the tympanic membrane produce 

A cone of light ( a triangle)

What is the function of the cochlea 

It converts mechanical energy (sound waves) into electrical impulses (neural signals), which are then delivered to the brain via the cochlear nerve 

What are the 3 parts of the cochlea

• Scala vestibuli

• Cochlear duct

• Scala tympani 

(Fluid filled compartments)

What is the function of scala vestibuli

Carries vibrations from the oval window 

What is the function of the cochlear duct 

It is the membranous labyrinth; it contains the organ of Corti (sensory organ)

What is the function of Scala tympani 

It carries dampened vibrations towards round window 

What happens in the organ of Corti

The vibrations of the cochlear duct which get sensed by the hair cells 

What is the tectorial membrane 

A gel-like structure that lies on the top of the hair cells 

What happens as the basilar membrane vibrates and how does it stimulate auditory nerve cells

It causes hair cells to move back and forth making their cilia bend. The bending triggers the release of glutamate that stimulates auditory nerve cells.

What do different frequencies do to the basilar membrane 

Different frequencies make different parts of the basilar membrane vibrate, which leads to the stimulation of different populations of hair cells 

How are stereocilia (cilia of the hair cells) arranged 

arranged in a row at progressive reduced height, connected by tip links that contain channels for K+

What two parts of the air mediate our perception of balance 

Semicircular canals and vestibule mediate 

What is utricle responsible for (2)

The linear acceleration in the horizontal plane (e.g in a car) and head tilt 

What is saccule responsible for 

The linear acceleration in the vertical plane  (e.g in the lift)

What are semicircular canals responsible for 

Rotational movement of the head and equilibrium 

At the end of every semicircular canal there is a swelling, what is the swelling called and what is within the swelling 

The swelling is called ampulla 

In the ampulla is a sensory organ called cristae ampullaris

What is otitis media 

An infection of the middle ear 

What can cause infections of the middle ear and how 

Cold and allergies can impair drainage from middle ear, building up fluid behind the tympanic membrane leading to infections 

Drug treatment for otitis media (2)

Otigo

Amoxicillin 

What is otigo

Ear drops that contain phenozone and lidocaine to reduce pain and swelling 

Phenazone: analgesic, antipyretic, anti inflammatory 

Lidocaine: local anaesthetic 

How do you apply otigo

Apply 4 drops 2–3 times a day

What antibiotics are given first line and second line etc 

Courses are usually 5 days

Amoxicillin 5-7 days is the first line of treatment 

Clarithromycin or erythromycin 5-7 days ( if allergic to penicillin)

co-amoxiclav (5-7 days) : Second choice (without penicillin allergy)

What is otitis externa 

Infection of the external ear (auricle)

What are the treatment options for otitis externa 

Ear drops with anti-inflammatory, anti-bacterial or antifungal drugs 

What is conductive deafness

happens when sound waves cannot travel properly through the outer or middle ear to reach the cochlea in the inner ear. Sounds often feel muffled, quieter, or blocked