Ear Anatomy + Disorders Flashcards
1
Q
What are the 3 key regions of the ear
A
External ear
Middle ear/ tympanic cavity
Inner ear/ Labyrinth
2
Q
What are the 4 parts of the Temporal Bone?
A
- Petromastoid
- Squamous
- Tympanic plate
- Styloid process
3
Q
Which part of temporal bone contains the middle and inner ear?
A
Petrous
4
Q
What opening is found on the inferior surface of the Petrous bone and what passes through?
A
Carotid canal, internal carotid passes through
5
Q
What are the Mastoid air cells?
A
Small air filled spaces within the mastoid process
6
Q
What do the Mastoid air cells communicate with and via what channel?
Why is clinically significant?
A
- Communicate with Middle Ear cavity
- Via the Mastoid Antrum (a bony channel)
- Potential spread of infection from Middle ear to mastoid air cells-> Acute Mastoiditis
(Entry to Mastoid Antrum from Middle Ear is called the Aditus)
7
Q
How is Acute Mastoiditis treated?
A
Surgery and IV Antibiotics
8
Q
What are the 2 parts of the External ear?
A
- Pinna/ auricle
- External Auditory/ Acoustic Meatus (EAM)
9
Q
Describe the Pinna/ Auricle of the External ear
A
- Cartilaginous And covered with skin
- Fleshy, fatty lobule at inferior end (Earlobe)
- Arranged into curved ridges, including a Helix and Tragus
- The Tragus guards the EAM
10
Q
Cauliflower ear results from what untreated condition?
A
Pinna Haematoma
11
Q
What is a Pinna Haematoma?
How is it treated?
A
Blood accumulation between cartilage and its overlying periochondrium
Drainage
Prevent re-accumulation
12
Q
Describe the EAM of the External ear
A
- Starts as a cartilaginous tube laterally-> Continues as a bony canal medially, formed by Tympanic Plate
- Lined with skin, which secretes Cerumen for protection (Not the inner bony part)
13
Q
What are 2 components of Earwax?
A
- Cerumen secreted from the EAM skin
- Discarded cells of the EAM skin
14
Q
Common conditions involving the EAM are;
- Wax
- Foreign bodies
- Otitis Externa
What is Otitis Externa?
A
- Inflammation of the External Ear Canal/ EAM
- Also called ‘Swimmer’s Ear’
15
Q
What is Malignant/ Necrotising Otitis Externa?
A
This is when the bacterial infection becomes more invasive and erodes through the bone of the ear
(Can affect facial nerve-> Palsy)
16
Q
List 5 causes of Otitis Externa
A
- Skin irritation from water/ shampoo/ soap
- Damage to skin in ear canal
- Increased build up of wax+H20-> Irritation + infection
- Skin problems (Eczema, Psoriasis)
- Hot humid weather
17
Q
What are 5 symptoms of Otitis Externa?
A
- Itching/ pain/ discomfort
- Watery discharge
- Dry flaky skin around outside of ear and along ear canal
- Discomfort moving jaw (chewing/ speaking)
- If severe, reduced hearing
18
Q
What is Medial and Lateral to the Tympanic membrane
A
Lateral: EAM
Medial: Middle ear
19
Q
Describe the Tympanic Membrane
A
- Fibrous
- Cone shaped, with apex pointing medially
- Translucent
20
Q
Describe 4 structural features of the Middle Ear
A
- Air filled
- Contains Ossicles
- Connected to Nasopharynx via Pharyngotympanic/ Eustachian Tube
- Lined with respiratory epithelium (ciliated pseudostratified columnar)
21
Q
What do the Ossicles do?
Name them from Lateral to Medial
A
Transmit vibrations from Tympanic Membrane to Inner Ear structures
Malleus, Incus, Stapes
22
Q
What is the purpose of Eustachian/ Pharyngotympanic Tube?
What is the clinical significance of the tube?
A
- Allows equalisation of air pressure between atmosphere and middle ear
- Necessary for efficient transfer of sound from middle to internal ear
- Potential route for infection to spread into middle ear
23
Q
What nerve carries general sensation from the middle ear?
A
Tympanic branch of Glossopharyngeal nerve (IX)
IX Also carries sensory info from Oropharynx
24
Q
Middle ear infections can also spread through bone to to structures in the cranial cavity.
Suggest 3
A
- Meninges
- Temporal Lobe
- Sigmoid Sinus
25
What kind of joints are the articulation between the Ossicles?
Describe the articulation between Stapes and the Inner Ear
Synovial joints
Stapes articulates with the Inner Ear at the Oval Window of the Cochlea
26
How does Osteosclerosis present?
- Gradual
- Unilateral or bilateral
- Conductive hearing loss
27
Describe the function of the Ossicles
- Transmit vibrations from an air medium to a fluid medium within the Cochlea
- Amplifying and Concentrating sound
28
Why can Osteosclerosis lead to hearing loss?
- Causes mature bone to be replaced with woven bone-> Footlate of Stapes FUSES to Oval Window
- Vibrations can’t be transmitted to inner ear-> Hearing loss
(Fusion can also be between Ossicles)
29
The Eustachian tube is usually closed.
| When is it intermittently opened?
By the pull of attached palate muscles when swallowing or yawning
30
What does the Stapedius muscle do?
What other muscle has same overall effect?
Dampens excessive vibration of the Stapes footplate at the Oval Window
Tensor tympani
31
What branch of the facial nerve runs over the inner surface of the Tympanic Membrane?
Chorda Tympani
32
Describe how a Cholesteatoma comes about
- Chronic negative pressure in middle ear-> Retraction of Pars Flaccida forms a Sac/ Pocket
- Trapping of Strat. Squamous epithelia+ keratin-> Proliferation into a Cholsteatoma
33
How does a Cholesteatoma present?
- Painless
- Smelly otorrhea
- May have hearing loss
34
What is the usual cause of a Cholesteatoma?
Chronic Eustachian Tube dysfunction-> Negative pressure in middle ear
35
A Cholesteatoma is not malignant but it slowly grows and expands.
Suggest a complication
Enzymatic destruction of bone (Ossicles/ petrous/ mastoid)
36
Describe the self cleaning function of the EAM
Epithelial Migration:
| - Epithelia moves laterally outwards from Tympanic Membrane
37
Suggest 3 non-otological causes of Otalgia
- TMJ dysfunction (Vc)
- Oropharynx diseases (IX)
- Larynx and pharynx diseases (IX and X)
38
Compare the appearance of the Tympnic Membrane in;
- Acute Otitis Media
- OM with Effusion
Acute OM;
- Outwards/ Lateral Bulging (due to raised pressure)
OM with Effusion;
- Retracted (pulled in medially)
- Evidence of fluid in middle ear
39
Describe Otitis Media with effusion
What is the usual cause?
How is treated?
- AKA ‘Glue Ear’, NOT an infection
- Fluid buildup and negative pressure in middle ear
- Eustachian tube dysfunction
- Most resolve spontaneously in 2 to 3 months
40
Why does OM with effusion cause hearing loss?
This condition is usually in children, how can it be managed temporarily?(resolves on its own in 2-3 months)
Fluid decreases mobility of TM and ossicles-> Hearing loss
Using Grommets, which act to equilibrate pressures between atmospheric pressure and middle ear
41
What is Acute Otitis Media?
What are 4 symptoms?
- An acute middle ear infection, more common in children/ infants
- Otalgia (Infants may pull/ tug at ear)
- Nonspecific infection symptoms (fever)
- Red TM, may be bulging
42
Describe the Aetiology of Acute Otitis Media
- Mostly viral
Occasionally bacterial;
- Strep pneumoniae
- Haemophilus influenzae
43
Why are children more susceptible to middle ear pathology than adults?
Eustachian tube is shorter + more horizontal so;
- Easier passage for infection to spread
- Tube can block more easily-> Impaired ventilation and drainage of middle ear
44
List 4 complications of Acute OM
- TM perforation
- CN VII involvement
- Mastoiditis
- Intracranial complications (Meningitis, sigmoid sinus thrombosis, brain abscesses)
45
What are the 4 parts of the Inner Ear/ Labyrinth?
- Cochlea
Vestibular apparatus;
- Utricle
- Saccule
- 3 Semicircular ducts and canals
46
What are 3 Semicircular canals/ ducts? (One for each possible plane of head rotation)
- Anterior
- Posterior
- Lateral
47
What do you call the fluid that fills the structures of the inner ear?
Endolymph
48
The Cochlea is the part of the Inner Ear responsible for hearing.
Describe how this works
- Stereocilia in the spiral Organ of Corti
- Respond to fluid motion (generated by Stapes ‘tapping’ on Oval Window) and generate an AP
- The AP moves down the Cochlear part of CN VIII to be perceived as sound
49
The Vestibular Apparatus is responsible for balance and position.
Describe this
- Stereocilia in Utricle and Saccule respond to Rotation Acceleration AND Pull of Gravity
- Stereocilia in Semicircular ducts/ canals respond to Rotational Acceleration in 3 different planes
- Head/body movement-> Fluid movement-> Bending of stereocilia-> Generating an AP
- The AP travels down Vestibular part of CN VIII to be perceived as our sense of Position and Balance
50
What are 3 general possible symptoms of inner ear pathology
- Hearing loss
- Tinnitus
- Disturbances to balance and vertigo
51
Compare Conductive and Sensorineural hearing loss
Conductive;
- Associated with Middle and External Ear
Sensorineural;
- Associated with Internal Ear
52
Some conditions affect BOTH hearing and balance, some affect ONLY one of the two.
List;
- 2 conditions that affect BOTH hearing and balance
- 1 condition that affects ONLY HEARING
- 1 condition that affects ONLY BALANCE
Affects Both;
- Meniere’s Disease
- Labyrinthitis
Affects only hearing;
- Presbycusis (Age related)
Affects only balance;
- Benign Positional Paroxysmal Vertigo (BPPV)
53
Describe the most common cause of Sensorineural hearing loss
How can it be treated?
Presbycusis;
- Associated with old age
- Hearing loss prevents Gradually and Bilaterally
- Initially affects ability to hear higher pitched sounds
- Can be treated with hearing aids
54
Describe the presentation of most common cause of Vertigo
| Only affects balance
Benign Positional Paroxysmal Vertigo, BPPV;
- Intermittent, short episodes of Vertigo (Seconds)
- Triggered by head movement
55
Name the test used to diagnose BPPV.
What’s the treatment?
Test: Dix-Hallpike
Treat: Epley manoeuvres
56
What is the typical triad of symptoms of Ménière’s disease?
Name 3 other symptoms
- Vertigo
- Hearing loss
- Tinnitus
- Nystagmus
- Aural fullness
- Nausea and vomiting
(Hearing May deteriorate over time)
57
Suggest 2 broad types of infection of inner ear
What is 1 similarity between them
- Acute Labyrinthitis
- Acute Vestibular Neuronitis
- History of Upper Respiratory Tract infection
58
What is the difference between Acute Labyrinthitis and Acute Vestibular Neuronitis
AL;
- ALL inner ear structures involved-> Vomiting, Vertigo and Hearing loss/ Tinnitus
AVN;
- Usually NO hearing disturbance/ tinnitus
- Sudden onset of Vomiting and severe vertigo (lasting days)
59
What can Rinne’s and Weber’s tests be helpful with?
When may we use them?
(Weber-forehead, Rinne- sides)
- Helpful to distinguish between Conductive and Sensorineural hearing loss
- When no immediately obvious cause can be identified
60
During an ear examination, examine both ears and avoid standing/ having to bend over.
How do we begin an ear examination?
Inspect and palpate the;
- Skin around Pinna
- Mastoid process
- Pinna itself
61
How is the EAM examined using an Otoscope?
- In an adult, pull Pinna UP, OUT and BACK to straighten EAM
| - In a child, pull Pinna DOWN and BACK
62
Describe 3 visual features of a normal Tympanic Membrane when looking through and Otoscope
- Translucent
- Handle/ Manubrium of Malleus seen near the centre
- TM is oblique so that Superior margin is closer to examiner’s eye
63
What does a bulging Tympanic Membrane indicate?
What do you call white plaques on the Tympanic Membrane?
Fluid or pus in Middle Ear
Tympanosclerosis
64
How would you differentiate between Meniere’s and Acute Labyrinthitis?
Meniere’s;
- Episodic, typically lasting a few hours
- Possible prior history of Aural Fullness
Acute Labyrinthitis;
- Symptoms last longer (days to weeks)
- Often sudden onset, possible prior history of URT Infection
