Lecture 9 - Anatomy + Ear Conditions Flashcards by Callum Donoher

What are the 3 parts of the ear?

External ear
Middle ear
Inner ear

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What are some signs and symptoms of ear diseases in general?

Hearing loss
Otalgia
Otorrhoea
Tinnitus
Vertigo
Facial nerve lesions/palsy

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What is otalgia?

Ear pain

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What is otorrhoea?

Ear discharge

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What is tinnitus?

When sound is perceived but is not actually coming from an external source
Like ringing, humming and whistling…

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What situation does facial nerve lesion/palsy occur as a result of ear disease and why?

Disease of the middle ear

Since the facial nerve (VII) runs through the canal of the Petrous bone

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What makes up the external ear?

Pinna
External auditory meatus
External auditory canal
Lateral surface of tympanic membrane

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What is the pinna/auricle?

The outside cartilaginous bit of the ear which most people refer to as the ear

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What type of cells line the external auditory canal?

Keratinised squamous epithelium

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What is the tympanic membrane?

What everyone refers to as the ear drum

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What type of cavity is the middle ear?

Air filled cavity

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What is found in the air filled cavity of the middle ear?

Ossicles

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What structures does the middle ear connect to?

Nasopharynx via Eustachian tube/pharyngotympanic tube (PT)

Mastoid process

Sigmoid dural venous sinus

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What fills the ducts/tubes of the inner ear?

Fluid

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What are the structures of the inner ear?

Vestibulocochlear nerve (VIII)

Semicircular canals

Vestibule = utricle + saccule

Cochlea

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What are the ossicles in the ear from attached to the tympanic membrane to deep?

Malleus
Incus
Stapes

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Go to the last slide and label the ear:

1 = Pinna
2 = External auditory canal/meatus
3 = Tympanic membrane
4 = Malleus
5 = incus
6 = stapes
7 = Eustachian tube/pharyngotympanic tube
8 = cochlea
9 = semicircular Canals
10 = cochlear nerve
11 = vestibular nerve
12 = external ear
13 = middle ear
14 = internal ear

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What cells line the inner ear?

Sterocilia

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What is the important bone relevant to the ear?

Temporal bone (Petrous part in particular)

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What are the 2 membranous sacs making up the vestibule portion of the inner ear?

Utricle

Saccule

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Which of the 2 membranous sacs of the inner ear (vestibule) receive the 3 semicircular canals?

Utricle

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What does the saccule connect to?

Cochlea

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What are the nerves supplying the external ear with general sensation?

Cervical nerves C2 and C3
Trigeminal nerve
Vagus
CN VII

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What nerve supplies the middle ear cavity and medial surface of tympanic membrane with sensation?

Glossopharyngeal (IX)

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What are some causes of refered pain to the ear (non ontological causes of otalgia)?

TMJ dysfunction Oropharyngeal disease like pharyngitis Laryngeal and pharyngeal cancers

Why can TMJ dysfunction lead to otalgia?

TMJ supplied by the Mandibular division of the Trigeminal nerve (Vc) The auriculotemporal nerve supplying the ear is a branch of the mandibular division of the Trigeminal nerve (Vc)

Why can pharyngitis lead to referred ear pain?

Pharynx supplied by the Glossopharyngeal nerve (IX) Glossopharyngeal nerve supplies middle ear

Why can laryngeal and pharyngeal cancers cause referred pain?

Pharynx and larynx supplied by CN IX and X Middle ear = IX External ear = X

What is the function of the external ear?

Focuses and transmits sound waves to the tympanic membrane

What is the pinna made of?

Cartilage Perichondrium Skin and fatty tissue (lobule)

What is the shape of the external accoustic meatus in adults?

Sigmoid shape

How does the structure of the outer 1/3 and inner 2/3 of the external acoustic meatus differ?

Outer 1/3 = cartilage Inner 2/3 = bone Both lined with skin

Which part of the external acoustic meatus is the hair, sebaceous and ceruminuos glands (wax producing) located?

Cartilage part

What happens to the dead desquamed keratinised squamous cells in the external acoustic meatus?

They migrate laterally away from the tympanic membrane where they mix with the wax

What can be seen with an otoscope?

External acoustic meatus External surface of tympanic membrane

How should the ear be manipulated to view the ear using an otoscope in an adult and why?

Pull up and back Since sigmoid shape

What bone is usually visible using an otoscope when looking at the tympanic membrane?

Malleus

What is the top of the tympanic membrane called?

Pars flaccida/attic

What is the bottom part of the tympanic membrane called?

Pars tensa

What is visible as a result of the otoscope examination process on the tympanic membrane?

Cone of light

Look at the last slide, label the tympanic membrane structures:

1 = manibrium of malleus 2 = pars flaccida 3 = pars tensa 4 = incus

What nerve can sometimes be visible on otoscopy? If damaged what symptoms can someone get?

Chords tympani Lose taste or dry mouth (parasympathetic lost)

What nerve can sometimes be visible on otoscopy? If damaged what symptoms can someone get?

Chords tympani Lose taste or dry mouth (parasympathetic lost)

What are white plaques on the tympanic membrane called?

Tympanic sclerosis

What causes tympanic sclerosis?

Previous trauma or irritation leading to healing being needed

What changes can occur to the tympanic membrane with middle ear pathology?

Bulging and erythematous Or Over retracted (normally retracted) Can indicate fluid in middle ear when it should be air

What is the function of the ossicles?

Relay and amplify vibrations from the Tympanic membrane to the oval window which then transmit these vibrations into waves in the fluid of the cochlea

What muscles dampen the vibrations of the ossicles if the nosies are very loud?

Tensor tympani Stapedius

What is the reflex called when the tensor tympani and stapedius muscles contract when the noise is too loud to dampen the noise?

Acoustic reflex

What is the condition called when the acoustic reflex is ineffective??

Hyperacusis

What can cause hyperacusis and why?

Facial nerve lesion Since a branch of the facial nerve is the nerve to stapedius , if this is damaged the stapedius muscle wont move the stapes bone

What lines the middle er?

Mucus membrane

What is special about the middle ear in terms of air flow?

Constantly drawing air into it so pressure in there is negative

What structure is important in equalising the negative pressure in the middle ear so it matches the pressure on the external ear side of the tympanic membrane?

Pharyngotympanic tube (Eustachian tube)

What happens to the tympanic membrane if there’s dysfunction in the pharyngotympanic tube?

Negative pressure builds up in middle ear retracting and pulling TM inwards

What diseases are caused by dysfunction of the pharyngotympanic tube?

Otitis media with effusion (glue ear) Cholesteatoma

Why are problems/complications with the pharyngotympanic tube more common in children/infants?

Its shorter nd more horizontal More easily blocked Opens to andenoid tonsils which are larger in kids Shorter pathway for infections to spread to middle ear

What are some important anatomical features related to the middle ear?

Eustachian tube Facial nerve Mastoid cells Sigmoid dural venous sinus Brain and cerbellum near (surrounded by meninges)

Why is a middle ear infection potentially dangerous?

Connects to many things Septic thrombi could form in sigmoid dural venous sinus Infection could spread to infect the meninges Abscess could compress brain Mastoid could get infected

What part of the inner nears is essential for sound?

Cochlea

What part of the inner ear is needed for balance?

Semicircular canals, utricle and saccule

What can disease of the inner ear cause?

Hearing loss Tinnitus Balance disturbance and vertigo (vestibular apparatus)

How does the vestibular system detect movement/balance?

Head movements move fluid in the semicircular canals Movement of this fluid moves the gelatinous matrix which the Sterocilia are embedded The movement of the Sterocilia generates action potentials to be sent along the vestibular portion of the vestibulocochlear nerve (VIII)

What are the calcium carbonate crystals Called found in the utricle and saccule?

Otoliths

How does the cochlea lead to hearing?

Vibrations of stapes at teh oval window makes waves in the fluid in the cochlea This moves the Sterocilia in the spiral organ of corti in the cochlea This generates action potentials to be sent along the vestibularcochlear nerve (VIII)

What is the process of hearing from sound to brain ?

Pinna and external auditory meatus focuses sound onto tympanic membrane This vibrates which sends vibrations across stapedius, incus to stapes which is at the oval window of the cochlea Waves generated in cochlear fluid This is sensed by Sterocilia in spiral organ of corti which generates action potentials in cochlear part of CN VIII Impulses send to temporal lobe (primary auditory cortex)

Go to the last slide and label the pinna:

1 = helix 2 = superior crus 3 = anti helix 4 = anti Tragus 5 = lobule 6 = tragus 7 = concha 8 = inferior crus