7 Flashcards
(67 cards)
1
Q
What are the 3 parts of the ear?
A
External, middle and inner
2
Q
What makes up the external ear?
A
- pinna
- external auditory meatus
- skin-lined
3
Q
What parts make up the middle ear
A
- air filled cavity
- ossicles
- lined with respiratory epithelium
- Pharyngotympanic tube connects it to oropharynx to help it communicate with each other
- allows it to maintain an equilibrium of pressure
4
Q
What parts make up the inner ear?
A
- cochlea
- semicircular canals
- fluid filled
5
Q
What are the four components of the temporal bone?
A
- squamous part
- petromastoid part
- tympanic plate
- styloid process
6
Q
What parts of the ear does the petrous part of the temporal bone contain?
A
Middle and inner ear
7
Q
What parts of the face does the branch of CN IX bring general sensation to?
A
- tonsils and pharynx
- posterior tongue
- middle ear
- medial surface of tympanic membrane
- mastoid air cells
8
Q
What parts of the ear does the nervus intermedius (CN VII) bring general sensation to?
A
- lateral surface of tympanic membrane
- external acoustic meatus
- concha
9
Q
What parts of the ear do the the cervical spine nerves bring general sensation to?
A
- posterolateral scalp
- superior pinna
- supra-auricular scalp
- angle of jaw
- majority of pinna
- skin over parotid gland and mastoid process
10
Q
What cranial nerve carries special sensory hearing and balance?
A
CN VIII vestibulocochlear
11
Q
What is significant about mastoid air cells?
A
- they are small air-filled spaces within the mastoid process
- there is a communication between these mastoid air cells and the middle ear cavity via the mastoid antrum
- has clinical relevance for the potential spread of middle ear infections to the mastoid air cells
12
Q
Why is the external ear shaped in such a way?
A
-in order to collect, transmit and focus sound waves onto the tympanic membrane
13
Q
Describe the auricle/pinna
A
- is cartilaginous and covered with skin
- has earlobe
- cartilage arranged in a number of ridges that act as guards for the external acoustic meatus
14
Q
What are some pinna/auricle abnormalities?
A
Perichondiritis
-inflammation of the pinna
Facial palsy and a painful, red ear with vesicles
- means you have an infection most likely caused by a varicella-zoster
- Ramsey-Hong syndrome: pt’s with facial nerve palsy and have rash on ear, may be on the inside of ear as well
- will have one side of face drooping
Pinna haematoma
- can lead to cauliflower ear
- often happens to rugby players
15
Q
What is a pinna haematoma?
A
- an accumulation of blood between cartilage and its overlying perichondrium
- secondary to blunt injury to the pinna
- subperichondrial haematoma: cartilage is deprived of blood supply since perichondrium is stripped off, which potentially can cause pressure necrosis of the tissue
- treatment: drainage and revent re-accumulation/re-apposition of two layers
- must apply special roll that pushes perichondrium on to cartilage so that bleeding stops
- if left untreated then fibrosis will occur, new asymmetrical cartilage development resulting in cauliflower deformity
16
Q
How long is the external acoustic meatus?
A
-2.5cm in length
17
Q
Describe the external acoustic meatus
A
- outer 1/3 is a cartilaginous tube but inner 2/3 is a bony canal (formed by tympanic plate)
- lined with keratinising, stratified squamous epithelium which is continuous onto lateral surface of tympanic membrane
- lining secretes cerumen (modifies sebum like wax) which protects the skin (only in cartilaginous part)
- is in a sigmoid shape
18
Q
Explain the self-cleaning function of the external acoustic meatus
A
- epithelial migration
- prevents skin shedding to block ear canal
- dead skin cells migrate laterally from tympanic membrane out to external acoustic meatus
- mixes with the secreted cerumen to form wax
19
Q
What are the common conditions present in the external acoustic meatus? Describe them
A
- Wax
- Foreign bodies
- Otitis externa: inflammation of the external ear
- ear canal becomes inflamed, swollen and may have discharge
- could be associated with eczema
- also can be caused by pseudomonas aeruginosa
- if it is malignant it is not cancerous, just very bad
- malignant can happen in immunocompromised or diabetics and it is very serious
20
Q
Describe the appearance of the tympanic membrane
A
- shaped like a shallow cone with apex pointing medially
- translucent
21
Q
What are some common abnormalities of the tympanic membrane?
A
Normal
-em
22
Q
What is a cholesteatoma?
A
- crusting of the pars flaccida
- retraction of pars flaccida forms a pocket
- this pocket traps stratified squamous epithelium and keratin
- the trapped cells morph into a cholesteatoma which will eat through everything
- usually secondary to a chronic Eustachian tube dysfunction
- the increasing negative pressure pull the “pocket” into the middle ear
- painless, often smelly otorrhea (ear discharge, with or without hearing loss)
- not malignant but slowly grows and expands
- potentially more serious consequences due to enzymatic bony destruction (eg. Erode ossicles, makes its way into brain)
- look at anatomy of ear slide 15
23
Q
Describe the middle ear
A
- aka tympanic cavity
- air filled space with some tiny bones
- ossicles connected via synovial joints and vibrations cause them to move
- they amplify and relay vibrations from the TM to oval window of cochlea
- lined with pseudostratified columnar epithelium (resp. Epithelium) which allows it to secret mucus and reabsob air to maintain NEGATIVE PRESSURE
- general sensation carried by glossopharyngeal nerve
24
Q
What is the significance of the pharyngotympanic tube (eustachian)?
A
- allows for communication between middle ear and external environment
- tube arises from nasopharynx
- allows for equalization of air pressure between middle ear and atmospheric necessary for transfer of sound energy
- allows for ventilation and drainage of mucus from middle ear
- but is also a potential route for infection to spread into middle ear
25
What are the three bones of the middle ear?
Malleus, Incus, Stapes
26
What muscles help to protect the cochlea from really intense vibrations?
- tensor tympani
- stapedius
- contract when there are excessive vibrations
27
What is otosclerosis?
- one of the most common causes of acquired hearing loss in young adults
- both genetic and environmental causes
- ossicles fused at articulations due to abnormal bone growth particular between base plate of stapes and oval window
- mature bone replaces with woven bone
- sound vibrations cannot be transmitted effectively to cochlea
- present with gradual unilateral or bilateral conductive hearing loss
- look at anatomy of ear slide 17
28
What is Otitis media with effusion (“glue ear”)?
- not an ACTUAL iNFECTION but can predispose to
- TM will appear retracted and have straw colour
- due to ET dysfunction
- increasing fluid and negative pressure in middle ear
- decreases mobility of TM and ossicles since they are in fluid, so will affect hearing
- often occurs in kids but will resolve spontaneously in 2-3 months
- may persist leading to speech and language impediment and development/school performatnce
- treatment: grommets (tympanostomy tube) which act to maintain pressure equilibrium by preventing buildup of negative pressure and make pressure equal to atmosphere pressure
29
What is acute otitis media?
- acute middle ear INFECTION
- more common in kids
- will have otalgia (infants may pull or tug at ear b/c earache)
- high temperature
- red and possibly bulging TM, loss of normal landmarks
- mostly viral aetiology
- occasional bacterial causes: streptococcus pneumonia, haemophilus influenzae
30
Why is it more common for kids to get middle ear infections?
- ET is shorter and more horizontal in babies
- so easier passage for infection from nasopharynx to middle ear
- tube can block more easily, compromising ventilation and drainage of middle ear, increasing risk of middle ear infection and “glue ear”
31
What are some complications of acute otitis media?
- tympanic membrane perforation
- facial nerve involvement (rare)
- close relationship to middle ear cavity (via facial canal)
- two intrapetrous branches run through middle ear cavity (Chorda tympani, nerve to stapedius)
- mastoiditis (osteomyelitis of mastoid bone)
- intracranial complications: meningitis, sigmoid sinus thrombosis, brain abcess
32
How is the facial nerve closely related to the middle ear?
- Chorda tympani runs across middle ear cavity and over TM, carrying taste from anterior 2/3 of tongue
- nerve to stapedius innervates stapedius
- thus middle ear pathology can potentially affect facial nerve
33
Describe the inner ear (labyrinth)
- contains structures involved in hearing and position sense/balance
- cochlea converts fluid movement (from stapes) into action potentials (in CN VIII) perceived as sound
- vestibular apparatus converts fluid movement (from head rotation) into actions potentials perceived as position sense and balance
- disease of the inner ear can present with hearing loss, tinnitus, disturbances to balance and vertigo
34
Describe the cochlea
- fluid-filled tube with specialized hair cells that generate action potentials when moved
- movements at the oval window set up movements of the fluid in the cochlear duct
- houses the spiral organ of Corti
- waves of fluid cause movement of special sensory cells (stereocilia) which generate action potentials in CN VIII
35
On a fundamental level, how do we hear?
- auricle and external auditory canal focuses and funnels sound waves towards tympanic membrane which vibrates
- vibration of the ossicles (stapes at oval window) set up vibrations movement in cochlear fluid
- sensed by stereocilia (nerve cells) in the cochlear duct (part called spiral organ of cartilage)
- movement of stereocilia in organ of Corti trigger action potentials in part of CN VIII
- primary auditory cortex (make sense of input)
36
Describe the vestibular apparatus
- includes semicircular ducts, saccule and uricles
- these are fluid-filled tubes containing stereocilia
- fluid movements due to moving position or rotation of head, bends stereocilia which generate action potentials via CN VIII to brain
- perceive and maintain sense of balance
37
What is presbycusis?
- sensorineural hearing loss associated with old age
- bilateral and gradual
- due to inevitable aging of hearing symptoms
38
What is benign paroxysmal positional vertigo?
- vertigo only
- short-lived episodes; triggered by movement of head
- only affects balance and the semicircular canals
- brain perceives that you are moving since the hairs are still moving but you’re actually not moving
- like spinning around in a chair really fast
- only affects inner ear
39
What is Ménière’s disease?
- vertigo, hearing loss and tinnitus (typically unilateral)
- too much endolymph in inner ear
- may feel nausea/vomiting
- symptoms longer-lasting
- recurrent episodes but recovery in between
- hearing may deteriorate over time
40
Compare and contrast acute labrythitis and acute vestibular neuronitis
- both have history of upper resp. Tract infection
- AL: involvement of all inner ear structures, associated with hearing loss/tinnitus, vomiting and vertigo
- AVN: usually no hearing disturbance or tinnitus
- sudden onset of vomiting and sever vertigo (lasting days)
- same symptoms as AL but hearing is spared
41
If a patient presents with hearing loss what tests would you do?
- inspect and palpate ear
- otoscopy
- gross hearing assessment (whisper words)
- tuning fork tests: Webers and Rennes
- Webers: on forehead
- Rinnes: on mastoid process
42
What is the difference between conductive and sensorineural hearing loss?
Conductive
- pathology involving external or middle ear such as:
- wax
- acute otitis media
- otitis media with effusion
- ostosclerosis
Sensorineural
- pathology involving the inner ear structures or CN VIII such as
- presbyacusis
- noise-related hearing loss
- Ménière’s disease
- ototoxic medications
- acoustic neuroma
43
What are the functions of the nose?
- sense of smel (olfaction)
- provides a route for inspired air
- filters inspired air by trapping particles in nasal hair mucus
- moistens (humidifies) and warms inspired air
- pseudostratified columnar with cilia lines the nasal cavity
- very vascular area so rich blood supply
- resonating chamber for speech
44
Describe the external nose
- mainly cartilaginous but also some bone
- frontal processes and maxillae of two nasal bones form the root (can be felt on nose bridge)
- common area for nasal bone fractures
45
What is the vestibule and what is it lined with?
- part of external nose that you feel when you stick your finger up your nose
- lined with skin containing sebaceous/sweat glands and hair
- filters inspired air
- inspired air enters via vestibule (of external nose)
46
What are the boundaries of the nasal cavity?
- roof: cribiform plate
- lateral walls: not smooth, has irregular surfaces
- medial wall: nasal septum
- floor: hard palate (roof of oral cavity)
- posteriorly communicates with nasopharynx and has opening into ET
47
Why are the lateral walls irregular?
-due to presence of bony projections which are formed by plates of bone covered by resp. Mucosa
3 bony projections (conchae)
- superior (part of ethmoid)
- middle (part of ethmoid)
- inferior
3 meatuses
- superior
- middle (has opening into maxillary air sinus
- inferior
- slows airflow by causing turbulence of airflow
- increases surface area over which air passes
- gives time for air to be humidified
48
Why do some people get runny nose when they cry?
- because nasal lacrimal duct connects the orbits into nasal cavity
- paranasal air sinuses also open into nasal cavity
- allows for drainage
49
Describe the nasal septum and what injuries can occur there
- front part of septum is made of cartilage while deeper part is made of bone
- bony part formed by perpendicular plate of ethmoid bone and volmer bone
- cartilage of septum receives rich blood supply from overlying perichondrium
- injury to nose can buckle perichondrium of septum and shear blood vessels
- as a result blood will accumulate between cartilage and perichondrium (sub-perichondrium) which will deprive cartilage of blood supply
- known as SEPTAL HAEMATOMA
- will cause necrosis of cartilage and affect shape of external nose
- treatment: aspirate blood and then tamponade it
- will see haematoma by looking up someone’s nose?
50
If a septal haematoma is left untreated, what can occur?
- can lead to avascular necrosis of cartilaginous septum
- saddling of nasal dorsum (saddle-nose deformity)
- pressures from blood causes necrosis of cartilage
- can also develop infection in the collecting haematoma
- septal abcess formation further increases likelihood of avascular necrosis of septum
51
While picking her nose one morning, the queen accidentally catches her nail on the nasal mucosa. The pain is intense, causing her to wince. Which CN carries general sensation from the nasal cavity?
- Trigeminal
| - facial nerve only carries parasympathetics to mucosal glands of nasal cavity
52
What are the two membranous linings of the nasal cavity?
Olfactory mucus membrane
- houses olfactory receptor neurones
- CN 1
Respiratory mucus membrane
- pseudostratified columnar ciliated epithelium rich in goblet cells
- filters using mucus/cilia
- humidifies using water secretions
- warms (rich blood supply)
53
What are nasal polyps? Explain
- fleshy, benign swellings of nasal mucosa
- usually bilateral: common (>40 years)
- pale or yellow in appearance, sometimes may be fleshy and reddened
- polyps usually come out just underneath the middle turbanate
- not really felt when poked
Symptoms
-blocked nose and water rhinorrhoea
-post-nasal drip (causes a tickly cough)
-decreased smell and reduced taste
-unilateral polyp with blood tinged secretion may suggest tumour
Look at nose and paranasal sinuses slide 14
54
What is rhinitis? Explain
- inflammation of the nasal mucosal lining
- many causes, all lead to similar symptoms:
- nasal congestion
- rhinorrhea (runny nose due to excess mucus production)
- sneezing
- nasal irritation
- postnasal drip
- common causes: simple acute infective rhinitis (viral, common cold)
- allergic rhinitis
55
6 y/o is brough to GP with discharge coming from his right nostril only. Over the last few days the discharge has become “smelly” and blood stained. Otherwise he is well. What is the likely diagnosis?
Foreign body
56
Explain why there is a rich blood supply to the nasal mucosa
- allows for warming and humidification of inspired air’
- mucosa and blood vessels are easily injuries
- causes nose bleed (epistaxis which can come from anterior or posterior side)
- arterial supply to nasal cavity arises from branches of opthalmic and maxillary artery
- arterial anastomoses in anterior septum (Kiesselbach’s plexus) are the most common source of bleeding in epistaxis
- easily treatable with simple first aid measure
- pinch nose and lean FORWARD b/c if you lean back, blood will go into GI tract and blood is very toxic which will make you sick
- venous drainage from nasal cavity into pterygoid venous plexus (also drainage to cavernous sinus and facial vein)
57
What areas of the nose will bleed?
- majority in kiesselbachs plexus
- 10% in sphenoplatine artery (branch of maxillary artery( (posterior)
- sphenoplatine is very difficult to treat because much harder to tamponade
58
What are paranasal sinuses?
- air filed spaces that are extensions of nasal cavity (rudimentary or absent at birth)
- four major ones: maxillary (2), frontal (2), ethmoid (2) and sphenoid
- lined with respiratory mucosa (ciliated and secrete mucus)
- help humidify and warm inspired air (reduce weight of skull)
- all drain into nasal cavity via small channels called Ostia into a meatus (mostly in middle meatus)
- infections in nasal cavity can involve sinuses (sinusitis)
- maxillary sinus is commonly affected
59
What are the anatomical relations of the paranasal sinuses?
- nasal cavity, orbit and anterior cranial fossa
- all sinuses drain into nasal cavity
- roots of upper teeth can sometimes project in maxillary sinus so problems in either teeth or sinus can affect the other
- general sensory innervation is from branches of CN V
- frontal, ethmoid and sphenoid —> Va
- Maxillary —> Vb
60
What is acute sinusitis?
- symptomatic inflammation of mucosal lining of nasal cavity and paranasal air sinuses
- often secondary to viral infection of nasal cavity or dental infections
- symptoms typically peak early but resolve gradually (last <10 days)
- can get pain and tenderness over the sinus involved
- clinical diagnosis (based on history and examination)
- recent URTI
- blocked nose and rhinorrhoea, potentially green/yellow discharge
- Pyrexia
- headache/facial pain (in area of affected sinus)
- worse on leaning forward
- self-limiting: treatment is symptomatic (ex. Analgesics, antipyretic, steam inhalation)
61
What is the pathophysiology of acute sinusitis?
- primary infection (ex. Rhinitis) leads to reduced ciliary function, oedema of nasal mucosa and sinus Ostia and increased nasal secretions
- drainage from sinus is impeded
- maxillary sinus is the most commonly affected
- stagnant secretions within the sinus become ideal breeding ground for bacteria (secondary infections)
- commonest bacteria include streptococcus pneumoniae, haemophilus influenzae, and moraxella catarrhalis
- acute BACTERIAL sinusitis is more likely if symptoms are particularly severe at onset and if they occur >10 days without improvement, and worsen after INITIAL improvement
62
How would you examine the ear canal in an otoscopy?
-pull pinna upwards, backwards and outwards
63
What does it mean if after doing a tuning fork test (Webers and Rinnes), you feel the vibrations more in the right ear than left ear?
- right ear is affected (conductive hearing loss)
| - left ear may be normal or have sensorineural hearing loss
64
Why can otitis media with effusion predispose to acute ear infection?
-increasing negative pressure will draw out trans update from middle ear which creates an environment for bacteria
65
What is an acoustic neuroma?
Non-cancerous growth that develops on CN VIII
66
What will Rinne’s and Weber’s test show for normal, conductive and sensorineural hearing loss?
Normal: AC>BC, centre
Conductive hearing loss: ACBC, lateral uses away from pathology
-external ambient noise is blocked out in bad ear
67
Which way will an acoustic neuroma grow?
- it will expand upwards and compress the trigeminal nerve
| - will not expand downwards and compress facial nerve
