Knowledge Base

Workings of otoscope

• Use largest speculum
• External auditory canal is very sensitive. Nerve endings are one cell thick.
• Air inflation otoscopy

Principle behind air insufflation otoscopy (Pneumo-otoscope)

Anatomy of external auditory canal and ear drum

• Age and direction of canal. External ear canal is crooked. To straighten
  • In Adults: Pull External ear upward and backward
  • In Children: Downward and backward
• External auditory canal is very sensitive. Nerve endings are one cell thick.
• Ear drum
  • Blood supply :Radial
  • Ossicles
    • Malleus, Chorda tympani, Stapes

• Diseases affecting external auditory canal
  • External Ottitis
  • Wax
  • Foreign body
• Diseases affecting ear drum
  • Perforation
  • Ottitis media
    • Red tympanic membrane
    • Bulging
    • Dull or absent light reflex
    • Diminished movement
    • Purulent material (air fluid level)

• Pathology of lesions affecting ear drum and external auditory canal

Ref:

1. Bates, A Guide to Physical Exam...