Module 3C ENT - LOs

Question 1

Basic anatomy of sinusitis
- what structures become blocked
- name the 4 paranasal sinuses

Answer 1

• The paranasal sinuses are hollow spaces within the bones of the face, arranged symmetrically around the nasal cavity
• They produce mucous and drain into the nasal cavities via holes called ostia
• Blockage of the ostia prevents drainage of the sinuses, resulting in sinusitis.
  .
  There are four sets of paranasal sinuses:
• Frontal sinuses (above the eyebrows)
• Maxillary sinuses (either side of the nose below the eyes)
• Ethmoid sinuses (in the ethmoid bone in the middle of the nasal cavity)
• Sphenoid sinuses (in the sphenoid bone at the back of the nasal cavity)

Question 2

Basic ear anatomy:
- Pinna
- External auditory canal
- Tympanic membrane
- Eustachian tube
- Malleus, incus, and stapes
- Semicciruclar canals
- Cochlear
- Vestibulocochlear nerve

Answer 2

• Pinna –> the external portion of the ear
• External auditory canal –> the tube into the ear
• Tympanic membrane –> the eardrum
• Eustachian tube –> connects the middle ear with the throat to equalise pressure
• Malleus, incus and stapes –> the small bones in the middle ear that connect the tympanic membrane to the structures of the inner ear
• Semicircular canals –> responsible for sensing head movement (the vestibular system)
• Cochlea –> responsible for converting the sound vibration into a nervous signal
• Vestibulocochlear nerve –> transmits nerve signals from the semicircular canals and cochlea to the brain

Question 3

Why would we use audiometry?

Answer 3

• Aduiograms can help identify and differentiate conductive and sensorineural hearing loss

Question 4

An example of a normal audiogram

Answer 4

• X-axis –> frequency (Hz)
• Y-axis –> decibels (dB)
• hearing is tested to establish the quietest volume at which a patient can hear each frequency
• Air and bone conduction are tested independently
• X –> left-sided air conduction
• O - right-sided air conduction
  .
• A pt with normal hearing should have readings in between 0 and 20 dB at the top of the chart

Question 5

Audiogram example –> sensorineural hearing loss

Answer 5

• Both air and bone conduction readings will be more than 20dB *plotted below the 20dB line on the chart

Question 6

Audiogram example –> conductive hearing loss

Answer 6

• you can see that the bone conduction readings are normal (between 0 and 20dB)
• air conduction readings are greater than 20dB (plotted below the 20dB line on the chart
• Bone conduction > Air conduction

Question 7

Audiogram example –> Mixed hearing loss

Answer 7

• Both air and bone conduction readings will be greater than 20dB
• However, there will be a difference of more than 15dB between the two (bone conduction > air conduction)

Question 8

What is the role of the Eustachian tube?

Answer 8

• Eustachian tube connects the middle ear and throat
• It’s main role is to equalise the air pressure in the middle ear and drain fluid from the middle ear
• If Eustachian tube is not functioning properly then fluid can build within the middle ear and air pressure becomes inequal
• Eustachian tube dysfunction may be related to a viral URTI, allergies, or smoking

Question 9

Tympanometry –> describe the process

Answer 9

• A device is insrted into the external auditory canal –> creating different air pressures in the canal
• A sound is sent in the direction of the tympanic membrane
• The amount of sound reflected back off the tympanic membrane is measured
• A tympanogram (graph) is plotted of the sound absorbed (admittance) at different air pressures
  .
  Note: the amount of sound absorbed by the tympanic membrane and middle ear (not reflected back to the device) is known as the admittance