Ear Flashcards
What nerves carry general sensation from the ear?
Cervical spinal nerves C2-3
Vagus
Trigeminal (auricotemporal)
Glossopharyngeal (tympanic)
What makes up the external ear?
Pinna
External auditory meatus
Lateral surface of tympanic membrane
What is the role of the external ear?
Collect, transmit and focus sound waves onto tympanic membrane
What is a pinna haematoma also known as?
Cauliflower ear
What causes a pinna haematoma?
Blunt injury to the pinna
What is a pinna haematoma?
Accumulation of blood between cartilage and its overlying perichondrium
What is the risk of a pinna haematoma?
Subperichondrial haematoma deprives cartilage of its blood supply
Risk of necrosis
How is a pinna haematoma managed?
Drainage and compression to prevent re-accumulation of blood
What is the external acoustic meatus?
Connects outer ear to tympanic membrane
How long is the external acoustic meatus?
~2.5 cm in length
What lines the external acoustic meatus?
Keratinising stratified squamous epithelium
What forms the structure of the external acoustic meatus?
Outer 1/3 = cartilaginous
Inner 2/3 = bony
What is the shape of the external acoustic meatus?
Sigmoid
How is the external acoustic meatus protected?
Cartilage part is lined by hair, sebaceous and ceruminous glands
What are ceruminous glands?
Wax producing glands
What are common conditions affecting the external acoustic meatus?
Wax
Otitis externa
What is otitis externa?
Inflammation of the external acoustic meatus
What is otitis externa also known as?
Swimmer’s ear
What can cause otitis externa?
Water trapped in ear
Damage to skin in ear
Skin problems
Wax build up
What are the symptoms of otitis externa?
Itching/pain in ear canal Watery discharge from ear canal Dry flaky skin around outside of ear and in canal Reduced hearing Discomfort when moving jaw
How is otitis externa managed?
Antibiotic + steroid ear drops
What are common abnormalities of the tympanic membrane?
Perforation
Bulging - due to otitis media
What is the middle ear?
Air filled cavity between tympanic membrane and inner ear containing ossicles
What is the role of the middle ear?
Amplify and relay vibrations from the tympanic membrane to the oval window tof the cochlea
What bones make up the ossicles?
Malleus
Incus
Stapes
What muscles are involved in the middle ear?
Tensor tympani
Stapedius
What is one of the most common causes of acquired hearing loss in young adults?
Otosclerosis
What is otosclerosis?
Condition where ossicles are fused at articulations due to abnormal bone growth
What bone is most commonly effected by otosclerosis?
Stapes
What type of hearing loss occurs in otosclerosis?
Conductive
What is the role of the pharyngotympanic tube?
Equilibrate pressure of middle ear with atmospheric pressure
Ventilation of middle ear
Drainage of mucus from middle ear
What is the pharyngotympanic tube also known as?
Eustachian tube
What is the pressure in the middle ear?
Negative pressure - mucous membrane reabsorbs air I middle ear
What is a cholesteatoma?
Sac of trapped epithelial cells that proliferate and erode
What causes cholesteatoma?
ET dysfunction - negative pressures pull ‘pocket’ into middle ear
What is the pathophysiology of cholesteatoma?
Retraction of area of tympanic membrane - forms a sac/pocket
Traps epithelial cells which proliferate and form cholesteatoma
What are the symptoms of cholesteatoma?
Painless smelly otorrhea
+/- hearing loss
What is the risk of a cholesteatoma?
Grows slowly and expands
Enzymatic bony destruction
What is otitis media with effusion?
Build up of fluid and negative pressure in middle ear
What is otitis media with effusion also known as?
Glue ear
What can cause otitis media with effusion?
ET dysfunction
What can be seen on otoscopy in otitis media with effusion?
Tympanic membrane retracted and straw coloured
How is otitis media with effusion managed?
Most resolve within 2-3 months
Grommets
What is acute otitis media?
Middle ear infection
Who does acute otitis media effect more commonly?
Infants/children
What are the symptoms of acute otitis media?
Otalgia
Fever
Red +/- bulging tympanic membrane
Why are ear infections more common in infants?
Eustachian tube is more horizontal and shorter
What are complications of acute otitis media?
Tympanic membrane perforation
Facial nerve involvement
Mastoiditis
Meningitis
What is mastoiditis?
Infection of mastoid air cells
What is the sign of mastoiditis?
Swollen red area behind ears
How does mastoiditis occur?
Middle ear cavity communicates with mastoid air cells via mastoid antrum - route for infections to spread
What is the inner ear?
Vestibular apparatus and cochlea
What is the role of the cochlea?
Converts vibration into an electrical signal which is perceived as sound
What is the role of the vestibular apparatus?
Maintaining our sense of position and balance
What is the cochlea?
Fluid-filled tube with specialized hair cells (stereocilia) that generate action potentials when moved
What cranial nerve is associated with the cochlea?
CN VIII - vestibulocochlear
What type of hearing loss is associated with cochlea/CNVIII dysfunction?
Sensioneural
How do we hear?
Auricle and external acoustic meatus focus sound waves towards tympanic membrane
Tympanic membrane vibrates
Ossicles vibrate and set up vibrations in cochlear fluid
Vibrations sensed by stereocilia in cochlear duct
Movement triggers CNVIII
Primary auditory cortex
What is the vestibular apparatus?
Semicircular ducts, saccule and utricle - fluid filled tubes that generate action potentials to do with balance
What cranial nerve is associated with the vestibular apparatus?
CNVIII
What conditions can affect the inner ear?
BPPV
Meniere’s disease
Labrynthitis
What is BPPV?
Benign paroxysmal positional vertigo
- short bursts of vertigo
- due to movements of head
- little crystals in vestibular apparatus
What is Meniere’s disease?
Progressive disease affecting vestibular apparatus and cochlear
What is labyrinthitis?
Infection of inner ear
What is the normal pattern in a Rinne’s test?
Air > bone
What occurs in Rinne’s test with sensorineural hearing loss?
Air > bone
What occurs in Rinne’s test with conductive hearing loss?
Bone > air
What is the normal pattern in a Weber’s test?
Midline
What occurs in Weber’s test with sensorineural hearing loss?
Lateralises to normal ear
What occurs in Weber’s test with conductive hearing loss?
Lateralises to the affected ear
What causes conductive hearing loss?
Pathology involving external or middle ear
Wax
Acute otitis media
Otitis media with effusion
Otosclerosis
What causes sensorineural hearling loss?
Pathology involving inner ear or CN VIII
Presbyacusis Noise-related hearing loss Meniere's disease Ototoxic medications Acoustic neuroma
What is presbyacusis?
Age-related hearing loss