1- Anatomy and physical examination of the auricle, external auditory canal and tympanic membrane

Describe the auricle

• composed of elastic cartilage covered with perichondrium and skin

What is the function of the auricle

• collect sound waves into the external ear canal → directional hearing

Describe the external auditory canal

• consists of an outer cartilaginous and inner bony part

• Canal curves and narrows to protect tympanic membrane

  • during otoscopy- ear is puleld upwards and back

What is the function of the external auditory canal

transmission of sound waves to the tympanic membrane

Describe the cartilaginous part of the external auditory canal

• covered by skin containing hair follicles and ceruminous glands that produce cerumen/ ear wax

• provides pathway for bacterial spread from parotid gland, infratemporal fossa and skull base

Describe the bony part of the external auditory canal

• covered by thin layer of skin, tightly adhering to periosteum

• glands and hair is absent

• between cartilaginous and bony part- stricture where foreign bodies can lodge

What is the tympanic membrane

• separates external ear from middle ear

• 3 layers- skin, fibrous tissue, mucosal layer

• thin, cone shaped membrane

What is the function of the tympanic membrane

• Sound waves cause vibration of the tympanic membrane

• → transmits these vibrations to the ossicles of the middle ear (malleus, incus, stapes)

What are the quadrants of the tympanic membrane

• anterior/ posterior + superior/ inferior

• 2 parts

  • Pars flaccida

  • pars tensa

What is the pars flaccida of the tympanic membrane

• has 2 layers- non fibrous tissue

• fragile

• associated with eustachian tube dysfunction and cholesteatomas

What is the pars tensa of the tympanic membrane

• has 3 layers

• comparatively robust

• “cone of light”- cone shaped light reflection of the otoscope light in anterior inferior quarant helps with orientation

• tympanic nerve passes in superior region

• for intervention, posteroinferior quadrant is chosen

What are the steps to examine the ear

• history

• inspection and palpatiion of auricle, mastoid and tissues around ear

• examination of external ear canal, first without speculum

• examine ear canal with aural speculum with head mirror and light source

• examine ear canal and tympanic membrane with otoscope

How do you examine the external ear canal without a speculum

• pull ear upwards and back

  • straightens external ear canal

• in infants- pull downwards

what are the types of otoscopy

• battery powered

  • battery powered light source with magnification

• pneumatic

  • detect perforation of tympanic membrane or fluid in middle ear

    • assess the mobility of tympanic membrane by applying positive and negative pressures with the rubber squeeze bulb

How do you clean the external ear

• can be blocked by ear wax/ cerumen, skin debris, purulent discharge

• wax removal and aural speculum + cerumen spoon or alligator forecepts

• fluid removal with suction or cotton tipped metal applicator

  • if no perforation of TM, can be cleaned by irrigation with water at body temperature

    • too warm or cold can cause vertigo