Understanding Ear Anatomy and Function

Why Do We Pop Our Ears?

• Protecting structures within the ear, especially the eardrum
• Preventing eardrum rupture due to pressure differences

Ear Anatomy Overview

• Sagittal Head Dissection: Used to study ear anatomy
• External Ear: External Auditory Canal
  • Part of the ear where ear wax forms
  • Contains ceruminous glands producing ear wax (cerumen)
  • Ear wax functions:
    • Prevents entrance of foreign bodies
    • Waterproofs the canal
    • Prevents the entry of pathogens

Ear Structures

• Eardrum (Tympanic Membrane): Divides external ear from middle ear
• Middle Ear (Tympanic Cavity):
  • Contains the smallest bones in the body: malleus, incus, stapes
  • Contains the smallest muscles: tensor tympani, stapedius
  • Important for hearing and protecting inner ear from loud sounds

How Hearing Works

• Sound waves enter the external auditory canal
• Tympanic membrane vibrates
• Vibrations transmitted through auditory ossicles
• Stimulates cochlea
• Information sent to the brain via vestibulocochlear nerve

Protecting the Inner Ear

• Muscles contract to limit vibrations from loud sounds
• Continuous loud sounds can be protected against; brief loud sounds cannot

Equalizing Ear Pressure

• Middle ear: closed system, air-filled; usually equalizes with atmospheric pressure
• Pressure differences can cause pain or rupture of tympanic membrane
  • Example: Scuba diving, atmospheric pressure increases, eardrum bulges inward
  • Example: Elevation changes, atmospheric pressure decreases, eardrum bulges outward
• Equalizing techniques: yawning, jaw movement, plugging nose and blowing

Eustachian Tube (Pharyngotympanic Tube)

• Connects middle ear to nasopharynx; normally closed
• Opens to equalize pressure through muscle contraction
• Dysfunction can prevent equalizing pressure, leading to pain and potential infections

Eustachian Tube Dysfunction

• Causes: Upper respiratory tract infections, colds
• Symptoms: Difficulty popping ears, fluid buildup, potential for middle ear infections (otitis media)
• More common in children due to anatomical differences

Middle Ear Infections (Otitis Media)

• More common in children
• Potential risks: eardrum rupture, pus buildup
• Debate in medical community about use of antibiotics
• Eardrums can heal on their own in 3-6 weeks
• Treatment: Tubes in eardrums to aid drainage