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2.3.1. Head, Neck & Neuroanatomy > Functional Anatomy and Disorders of the Ear > Flashcards

Functional Anatomy and Disorders of the Ear Flashcards

1
Q

The ear can be broadly categorised into what 3 parts?

A

External

Middle

Inner

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2
Q

What is otalgia?

A

Ear pain

Can sometimes be referred pain from another site of the body

Diverse sensory innervation of the ear = sources outside of the ear that share similar nerve innervation may present with otalgia e.g. laryngeal cancers

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3
Q

What is tinnitus?

A

Ringing/buzzing

Damage and loss of the tiny sensory hair cells in the cochlea of the inner ear.

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4
Q

What is vertigo?

A

Feels like the room is spinning when it is not

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5
Q

Within which bone of the skull do we find parts of the ear?

A

Petrous part of the temporal bone

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6
Q

What is the main function of the external ear?

A

Collects, transmits and focuses sounds waves into the tympanic membrane

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7
Q

Describe the anatomy of the external ear

A

Shaped by cartilage

External acoustic meatus = sigmoid shape

Pinna

Lateral surface of tympanic membrane

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8
Q

Discuss some possible abnormalities of the pinna

A

Congenital

Inflam

Infective = reactivation of varicella-zoster virus in the geniculate ganglion - shingles can effect facial N giving ipsilateral facial palsy (Ramsey Hunt syndrome)

Traumatic = cauliflower deformities (bleeding between tissues, cartilage effects, shape distorted)

Pinna haematoma = blood between cartilage and perichondrium - deprives cartilage of blood supply and pressure necrosis of tissue – prompt drainage needed = untreated leads to fibrosis and new asymmetrical cartilage devel

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9
Q

Outline the structure of the external acoustic meatus

A

Skin-lined

S shaped = have to pull ear up and back when examining

Cartilaginous (outer 1/3) and bony (inner 2/3) parts

Cartilaginous = glands for wax, hairs for protection

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10
Q

How long is the external acoustic meatus?

A

2.5cm

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11
Q

What are the common conditions involving the external acoustic meatus?

A

Wax = can become impacted and stop vibrations reacting TM

Otitis externa = inflam, may have exudate (causes = infect, eczema) AKA swimmers ear

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12
Q

Describe some common abnormalities of the tympanic membrane

A

Perforation = trauma, pressure on the inside of TM

Bulging secondary to otitis media

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13
Q

What does a normal tympanic membrane look like?

A

Pale grey semitransparent ovoid cone shaped disc located at the end of the external auditory canal

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14
Q

What normal structures can be seen when visualising the tympanic membrane?

A

Incus

Umbo

Pars tensa

Cone of light

Manubrium of malleus

Short process of malleus

Pars flaccida

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15
Q

Describe the anatomy of the middle ear

A

Full of air

3 ossicles = translate vibrations from tympanic membrane to inner ear = transmit vibration from air to water

1) Malleus
2) Incus
3) Stapes (smallest bone in the body)

Connected via synovial joints

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16
Q

What is the role of the ossicles?

A

Relay vibrations from tympanic membrane to the cochlea via the oval window

Amplify vibrations

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17
Q

What muscles are involved in the acoustic reflex?

A

Tensor tympani

Stapedius – supplied by facial N

Muscles contract to dampen any potentially excessive vibration due to loud noice

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18
Q

What is hyperacoustis?

A

Facial N problem = loose stapedius that contracts to prevent excessive vibration

Sensitivity to loud noises

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19
Q

What is otosclerosis?

A

Fusion of the ossicles at articulations – particularly at base plate of stapes and oval window

Sound vibrations cannot be transmitted

Gradual hearing loss

20
Q

What is the eustachian tube?

A

Prevents -ve pressure getting to large = allows equilibration of pressure within middle ear cavity with that of the atmosphere

Also allows for ventilation of and drainage of mucus from the middle ear

21
Q

How is -ve pressure generated in the middle ear?

A

Mucous membrane continuously reabsorbing air

22
Q

Describe otitis media with effusion (glue ear)

A

Build up of transudate fluid and -ve pressure in middle ear = retracted tympanic mem

Due to eustachian tube dysfunction

Decreases mobility of tympanic mem = affecting hearing

Treat = resolve spontaneously, insert grommets to equilibrate pressure

23
Q

What is acute otitis media?

A

Middle ear infection

More common in infants/children = due to eustachian tube being shorter and more horizontal = easier for infect to track from back of the throat to middle ear

Red +/- bulging TM = loss of normal landmarks

24
Q

What are the potential complications of acute otitis media?

A

TM perforation

Facial N involvement

Mastoiditis

Intracranial complications = meningitis, brain abscess

25
Q

What is mastoiditis?

A

Inflam of mastoid process

= middle ear cavity communicated via mastoid antrum with mastoid air cells = potential route for middle ear infections to spread into the mastoid bone

26
Q

How does mastoiditis present?

A

Ear pushed forward

Bone swollen, red

27
Q

Outline the important relationship the middle ear has with the facial N

A

Chorda tympani runs through middle ear cavity

Facial N may be involved in middle ear pathology

28
Q

What is cholesteatoma?

A

Abnormal skin growth into middle ear behind TM

Can erode through ossicles

Present = painless smelly discharge, top of TM crusting (sac that is eroding into middle ear cavity)

29
Q

Describe the anatomy of the inner ear

A

Filled with liquid

Cochlea = converts vibration into electrical signal perceived as sounds

Vestibular apparatus = maintains our sense of position and balance

30
Q

Outline the stages of ‘how we hear’

A

Auricle and external auditory canal focuses and funnels sound waves towards tympanic membrane which vibrates

Vibration of the ossicles (stapes at the oval window) sets up vibrations/movement in cochlear fluid

Sensed by stereocilia (nerve cells) in the cochlear duct (part called the spiral organ of Corti)

Movement of the stereocilia in organ of Corti trigger action potentials in cochlear part of CN VIII

Primary auditory cortex (make sense of the input)

31
Q

What makes up the vestibular apparatus?

A

3 Semicircular ducts in diff planes - fluid filled

Saccule + Utricle = hair cell that sense motion of fluid

Fluid filled series of channels that respond to position and rotation

Maintain sense of balance

32
Q

Name some diseases of the inner ear

A

Meniere’s Disease = too much fluid in the cochlear duct and vestibular apparatus, issue with drainage, fullness, cant hear, ringing, episodes of vertigo

Benign Paroxysmal Positional Vertigo = short bursts of vertigo, crystals in vestibular apparatus fluid, movement dislodges crystals, moves fluid, moves stereocilia, sensation of movement

Labrynthitis = inner ear infect

33
Q

What signs and symptoms present with inner ear pathology

A

Vertigo

Hearing loss and tinnitus

Nystagmus

34
Q

How can hearing loss be assessed?

A

Whispering word

Webers test

Rinne test

35
Q

What is the difference between conductive and sensorineural hearing loss?

A

Conductive = pathology in external or middle ear

Sensorineural = pathology in inner ear, or CN, or CNS

36
Q

What is presbyacusis?

A

Sensorineural hearing loss

Most common type in >55

Old-aged related hearing loss, both ears

37
Q

In someone with normal hearing, what will be louder, bone or air conduction?

A

air

38
Q

Outline the air conduction pathway of sound

A

ear canal –> TM –> ossicles –> cochlea –> CN8 Vestibulocochlear N

39
Q

Outline the bone conduction pathway of sound

A

vibrations of skull bones –> cochlear –> CN8 Vestibulocochlear N

40
Q

What is conductive deafness?

A

deafness due to ear canal, TM or middle ear

bone conduction = better hearing

41
Q

What is sensorineural deafness?

A

deafness due to the cochlear, Vestibulocochlear N or brain

air conduction = better hearing BUT both reduced

42
Q

Outline the webers test

A

assess = compares sensitivity of both cochlear

tap tuning fork, place tuning fork on top of head, sound better on one side or another?

sound via bone conduction

  • normal = sound equal
  • unilateral sensorineural deafness = quieter in 1 ear
  • unilateral conductive deafness = louder in 1 ear (due to removal of background noise)
43
Q

Outline the rinne test

A

assess = compares air and bone conduction

tap tuning fork, place over mastoid process, then place in front of ear – which one was loudest?

  • normal = loudest in front of ear (air provides best sound conduction)
  • conductive = bone conduction louder
  • sensorineural = air conduction louder
44
Q

Name the 3 ossicles

A

1) Malleus
2) Incus
3) Stapes (smallest bone in the body)

45
Q

Which nerves are involved in carrying general somatic sensation from the external ear?

A

Cervical nerve (C2)

Mandibular division of trigeminal nerve

Vagus nerve

2.3.1. Head, Neck & Neuroanatomy (17 decks)

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