Functional Anatomy And Disorders Of The Ear Flashcards
What is the ear for?
Hearing and balance
What are the three parts of the ear?
External Middle Inner
What are the symptoms and signs of ear disease?
Otalgia (ear pain) Tinnitus Discharge Vertigo Hearing loss Facial nerve palsy
Why Can otalgia be referred pain from another site?
Diverse sensory innervation of the ear If share similar nerve innervation e.g. Laryngeal cancers
Within which bone of the skull do we find the parts of the ear?
Temporal bone
peatrus part of temporal bone
What is the external ear made up of?
Pinna External auditory meatus Lateral surface of tympanic membrane
What does the external ear do?
Collects Transmits and focuses sound waves onto tympanic membrane
What abnormalities of the pinna are there?
?
What causes a pinna haemotoma?
Secondary to blunt injury to the pinna (Compact sports)
What is a pinna haemotoma?
Accumulation of blood between the cartilage and perichondrium Deprives the cartilage of its blood supply and pressure necrosis of tissues
What is the treatment of pinna haematoma?
Prompt drainage Measures to prevent reaccumulation or reap position of two layers
What is the deformity if pinna haematoma is not treated properly?
Cauliflower deformity As leads to fibrosis and new asymetrical cartilage develops
What is the external acoustic meatus?
Ear canal (skin lined cul de sac)
What shape is the external acoustic meatus?
Sigmoid shape Pull Up and back when examining
What is the external acoustic meatus made of?
Outer 1/3 cartilage Inner 2/3 bony
Where is hair and waves produced within the external acoustic meatus?
Cartilaginous part
What does wax and hairs do within the external acoustic meatus?
Prevents objects entering deeper into the ear canal Aids in desquatmation and skin migration out of canal
How long is the external acoustic meatus?
Around 2.5 cm
What are some common conditions of the external acoustic meatus?
Wax Otitis externa
What are some common abnormalities of the tympanic membrane?
Perforation Bulging secondary to otitis medulla
What is the middle ear made up of?
Ossicles and an air filled cavity
What does the air filled cavity contain?
Three ossicles which amplify vibrations from the tympanic membrane to the choclea via the oval window
What are the three ossicles?
Malleus Indus Stapes
What are the ossicles connected by?
Synovial joints
What do ossicles transmit vibrations from and to (mediums)
Air medium to fluid medium
What is movement of the ossicles tampered by?
Tensor tympani Stapedius (Muscles)
If loud noice what happens to the tensor tympani and stapedius?
Contract if potentially excessive vibrations due to loud noice Protective- acoustic reflex
What is otosclerosis?
When ossicles become fused at articulation e.g. Between base plate of staples and oval window Sound vibrations not transmitted so causes deafness
In the middle ear what does the pharyngotypanic tube do?
Equilibriates pressure of middle ear with atmospheric pressure
How does pharyngotympanic tube equilibrilate pressure?
Mucous membrane of middle ear continuously reabsorbs air in the middle ear causing negative pressure So the tube allows equilibration of pressure with the atmosphere Allows Venitalation and drainage of mucus from middle ear
What is otitis media effusion?
Glue ear Not infection Build up of fluid and negative pressure in middle ear due to tube dysfunction This can predispose to infection Affects hearing as decreases motility of TM and ossicles Most resolve on there own in 2-3 months May require grommets to ventilate ear
What is acute otitis media?
Acute middle ear infection More common in infantsOtalgia so infants may tug or pull at the ear Temperature and other non-specific symptoms Red and bulging TM and loss of normal landmarks
What does the phayngotympanic tube being shorter and more horizontal mean for infants?
Shorter and more horizontal in infants so easier passage for infection from nasopharynx to middle ear and tube can block more easily so ventilation if compromised and drainage of middle ear means increasing risk of middle ear infection
What are some complications of acute otitis media?
Tympanic membrane perforation, facial nerve involvement Rare but potential life threatening complications e.g. mastoiditis, intracranial complications like meningitis, sigmoid sinus thrombosis and brain abscess
How does mastoiditis occur?
Middle ear cavity communicated via mastoid antrum with mastoid air cells, this provides a potential route for middle ear infections to spread into mastoid bone?
What is the middle ears relationship with the facial nerve?
Facial nerve and one of its branches- Chorda tympani runs through the middle ear cavity May therefore be involved in pathology
What is cholestaetoma?
Abnormal skin growth growing into middle ear behind the tympanic membrane Sac or cyst of skin cells
What are the symptoms of cholesteatoma?
Painless, smelly otorrheea (ear discharge) may have hearing loss, may have serious neurological complications Secondary to chronic ET dysfunction or ear infections
Is cholesteatoma malignant?
Not malignant but slowly grows and expands eroding sturctures like ossicles, mastoid bone and cochlea
What makes up the inner ear?
Vestibular apparatus and Chochlea (fluid filled tubes)
What is the cochlea?
Our organ of hearing Fluid filled tube
What does the cochlea do?
convert vibrations into electrical signals (action potentials which is percieved as sounds
How does the cochlea work?
Movements at oval window set up movements of fluid in the cochlea Waves of fluid cause movement of special sensory cells (stereocilia) within the cochlear duct which generate action potentials in the CN VIII
What does the vestibular apparatus do?
maintains our sense of position and balance
What are the three parts of the vestibular apparatus?
Semicircular ducts, saccule and utricle
What is the vestibular apparatus?
Fluid filled series of channels and sacs that respond to position and rotation and maintain out sense of balance
What are the diseases of the inner ear?
Meniere’s disease, Benign paroxysmal position vertigo, labrynthetis
What are the symptoms of diseases of the inner ear?
vertigo, hearing loss and tinnitus, nystagmus
What would you do with a patients with hearing loss?
Take a history Examine- inspect external ear and surround areas otoscopy If hearing loss then gross hearing assessment, tuning forks and referral for more formal audiometry testing
What do you do in a gross hearing assessment?
Whispering a work or number and a patient repeating back while masking the ear not being tested
What would be Rinne and Webers tuning test show?
Differentiates between conductive and sensorineural hearing loss
What is conductive hearing loss?
pathology involving external and middle ear Wax, otitis media, glue ear or otosclerosis
What is sensorineural hearing loss?
pathology involving the inner ear or CN VIII Prebyacusis, menieres disease, Acoustic neuroma, ototoxic medications
What happens in a Rinne and Weber test?
What can pinna abnormalities be?
Congenital
Inflammatory
Infective
Traumatic
What is ramsey hunt syndrome?
Ipsilateral facial weakness with vesicles around the ear
Shingles of the facial nerve
What is nystagmus?
Involuntary eye movement
What is otitis externa?
Inflammation of external ear
How otitis externa treated?
Antibiotic eardrops
What is another name for otitis externa?
Swimmers ear
What can cause ear perfuration?
Trauma e.g. from cotton bud
Build up of pressure on the other side
