Ear & Taste Anatomy Flashcards

1
Q

Name the 5 foraminae in the temporal bone

A
  • External acoustic meatus
  • Internal acoustic meatus
  • Stylomastoid foramen
  • Petrotympanic fissure
  • Extracranial opening of carotid canal
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2
Q

What 2 structures make up the external ear?

A
  • Pinna (auricle)

- External acoustic meatus (ear canal)

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3
Q

What is the pinna of the external ear formed from?

A

Avascular elastic cartilage

so nutrients are gained from the skin

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4
Q

What is the function of the pinna?

A

To collect soundwaves and funnel them into the external acoustic meatus

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5
Q

The lateral 1/3rd of the external acoustic meatus is formed by…
A. Cartilage
B. Bone

A

A. Cartilage

The medial 2/3rds are formed by bone (the petrous part of the temporal bone)

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6
Q

Which cells in the epithelial lining of the external acoustic meatus produce earwax?

A

Ceruminous glands

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7
Q

What structure marks the medial end of the external acoustic meatus?

A

The tympanic membrane

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8
Q

Which spinal nerves supply the majority of the pinna of the external ear?

A

C2 and C3

via the lesser occipital and greater auricular nerves

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9
Q

Which nerve supplies the superior external acoustic meatus and most of the tympanic membrane?

A

CN V3

via the auriculotemporal nerve

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10
Q

Which nerve supplies the inferior external acoustic meatus and part of the tympanic membrane?

A

CN X - the vagus nerve

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11
Q

When using an otoscope to look in the ear, what direction should you pull the pinna in…
-An adult
-A child
?

A

Adults: posterosuperiorly (as the EAM is curved)

Children: posteroinferiorly (as the EAM is short and straight)

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12
Q

Name the thin part of the tympanic membrane

Is it superior or posterior?

A

Pars flaccida

Superior

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13
Q

Name the thick part of the tympanic membrane

Is it superior or posterior?

A

Pars tensa

Posteroinferior

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14
Q

What is the function of the middle ear?

A

To conduct soundwaves from the external ear through the tympanic cavity and towards the inner ear

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15
Q

Name the auditory ossicles of the middle ear

A

Malleus
Incus
Stapes

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16
Q

The auditory ossicles decrease in size from lateral to medial. This helps to…

A

Amplify sound

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17
Q

What type of joint connects the auditory ossicles?

A

Synovial joints

malleoincal and stapeoincal

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18
Q

What does the footplate of stapes connect to?

A

The oval window of the optic capsule of the inner ear

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19
Q

The middle ear is found in the tympanic cavity. Name the 2 parts of the tympanic cavity

A

Epitympanic recess (superior to tympanic membrane)

Tympanic cavity proper

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20
Q

Which nerve delivers sensory information to the mucosa lining the tympanic cavity?

A

CN IX - the glossopharyngeal nerve

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21
Q

Name the 2 muscles of the tympanic cavity

A

Tensor tympani

Stapedius

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22
Q

Tensor tympani:
Which auditory ossicle does it insert onto?
What nerve innervates it?

A
  • Malleus (runs from cartilaginous portion of eustachian tube to handle of malleus)
  • CN V3 (mandibular division of trigeminal)
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23
Q

Stapedius:
Which auditory ossicle does it insert onto?
What nerve innervates it?

A
  • Stapes (runs from the pyramidal eminence to the neck of stapes)
  • CN VII (facial nerve)
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24
Q

What is the function of…
-Tensor tympani
- Stapedius
?

A
  • Tensor tympani: dampens sound by reducing vibrations of the tympanic membrane (by pulling on the handle of malleus)
  • Stapedius: dampens sound by reducing vibrations of stapes on the oval window
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25
Q

Describe the acoustic reflex in relation to the tensor tympani and stapedius muscles

A

Loud noises cause tensor tympani and stapedius to contract, which dampens the sound to protect the nerves from damage

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26
Q

What is the function of the Eustachian tube?

A

To equalise air pressure between the middle ear and nasopharynx

This is ideal for vibration of the auditory ossicles

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27
Q

The cartilaginous portion of the Eustachian tube is usually collapsed. Which muscles contract to open it?

A

The soft palate muscles

tensor veli palatini and levator veli palatini muscles

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28
Q

When would the Eustachian tube be opened?

A

When atmospheric pressure changes

e.g., increased atm. pressure under water, decreased atm. pressure at high altitidues

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29
Q

Increased atmospheric pressure (e.g., under water) pushes the tympanic membrane IN/OUT, resulting in reduced vibrations of the ossicles and muffled hearing

A

IN

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30
Q

Decreased atmospheric pressure (e.g., in a plane) pushes the tympanic membrane IN/OUT, resulting in reduced vibrations of the ossicles and muffled hearing

A

OUT

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31
Q

The posterior 1/3rd of the Eustachian tube is formed by…
A. Cartilage
B. Bone

A

B. Bone

The remainder is formed by cartilage

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32
Q

What is the torus tubarius?

A

The opening of the Eustachian tube in the nasopharynx

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33
Q

Why can tonsilitis/pharyngitis cause otitis media?

A

Bacteria/ viruses can spread from the nasopharynx, through the Eustachian tube, and into the middle ear

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34
Q

Why is otitis media more common in children?

A

They have a shorter and more horizontal Eustachian tube

35
Q

Why can inflammation of the tonsils or pharynx lead to referred pain in the ear?

A

They have a common nerve supply:

The glossopharyngeal nerve (CN IX) provides sensory information to the mucosa of the…

  • Middle ear & eustachian tube
  • Naso- and oropharynx
  • Palatine tonsils
36
Q

Which branch of the glossopharyngeal nerve (CN IX) supplies the middle ear?

A

The tympanic branch (via the tympanic plexus lying on the promontory)

37
Q

What forms the promontory (bump) in the medial wall of the tympanic cavity?

A

The cochlear of the inner ear

38
Q

The internal carotid artery is closely related to the…
A. Roof of the tympanic cavity
B. Floor of the tympanic cavity
C. Anterior wall of the tympanic cavity

A

C. Anterior wall of the tympanic cavity

39
Q

The internal jugular vein is closely related to the…
A. Roof of the tympanic cavity
B. Floor of the tympanic cavity
C. Anterior wall of the tympanic cavity

A

B. Floor of the tympanic cavity

40
Q
The mastoid aditus/antrum opens into the air cells of the mastoid process. Which wall of the tympanic cavity is the mastoid aditus found in?
A. Anterior
B. Posterior
C. Lateral
D. Medial
A

B. Posterior

41
Q

Infection of the mastoid aditus (mastoiditis) can cause which condition?

A

Osteomyelitis

42
Q

How can the mastoid aditus be used in surgery?

A

It can provide surgical access to the tympanic cavity (but watch out for the facial nerve in the facial canal)

43
Q

What are the two main features of the anterior wall of the tympanic cavity?

A

The Eustachian tube

The chorda tympani

44
Q

What structure carries the facial nerve (CN VII) through the tympanic cavity?

A

The facial canal

45
Q

The stapes communicates with the inner ear via the…

A

Oval window

46
Q

Describe the location and structure of the inner ear

A
  • Located in the petrous portion of the temporal bone

- Consists of a bony otic capsule with an inner membranous labyrinth

47
Q

The bony otic capsule is full of PERI-/ENDO- lymph which is similar to EXTRA-/INTRA- cellular fluid

A

The bony otic capsule if full of PERIlymph which is similar to EXTRAcellular fluid

48
Q

The inner membranous labyrinth is full of PERI-/ENDO-lymph which is similar to EXTRA-/INTRA-cellular fluid

A

The inner membranous labyrinth is full of ENDOlymph which is similar to INTRAcellular fluid

49
Q

Why is the otic capsule made of denser bone than the rest of the temporal bone?

A

It is fully developed at birth (i.e., no bone turnover occurs)

50
Q

What are the 3 parts of the inner ear?

A
  1. Cochlear
  2. Vestibule (utricle + saccule)
  3. 3 semicircular canals
51
Q

Which parts of the inner ear are involved in…
-Hearing
-Balance and head movement
?

A
  • Hearing: Cochlear

- Balance: Vestibule + semicircular ducts

52
Q

Name the 3 semicircular ducts. How are they orientated in relation to each other?

A

Anterior, lateral and posterior semicircular duct

They are found at right-angles (90 degrees) to each other

53
Q

Which 2 semicircular ducts have a common stalk?

A

Anterior and posterior

54
Q

In the inner ear, the conversion of mechanical to neural stimuli is achieved by what type of cell?

A

Mechanoreceptors called hair cells

55
Q

How are hair cells stimulated in the vestibular apparatus?

A

By the movement of endolymph in the membranous labyrinth

56
Q

In what 2 locations are hair cells found in the vestibular apparatus of the inner ear?

A
  • The maculae of the utricle and saccule

- The ampullae of the semicircular ducts

57
Q
Angular movement change (e.g., nodding, shaking head, putting head on shoulders) is detected by hair cells in the...
- Utricle
- Saccule
- Semicircular ducts
?
A

Semicircular ducts

58
Q
Horizontal movement change is detected by hair cells in the...
- Utricle
- Saccule
- Semicircular ducts
?
A

Utricle

59
Q
Vertical movement change is detected by hair cells in the...
- Utricle
- Saccule
- Semicircular ducts
?
A

Saccule

60
Q

Hair cells convert fluid motion into neural stimuli. Which nerve carries the neural stimuli from the vestibular apparatus to the CNS?

A

The vestibular nerve

61
Q

The vestibular and cochlear nerve join to form which cranial nerve?

A

The vestibulocochlear nerve (CN VIII)

62
Q

Which part of the inner ear does the oval window connect with?

A

The cochlear

63
Q

Describe transition of pressure waves to neural stimuli in the cochlear

A
  • Vibration of stapes against the oval window creates pressure waves in perilymph and endolymph
  • Hair cells in the membranous labyrinth are moved
  • This stimulates action potentials which carry neural signals to the brain via the cochlear nerve
64
Q

What structure dampens the pressure waves in the cochlear apparatus?

A

The round window

65
Q

Name the 3 fluid-filled channels of the cochlear apparatus

A
  • Scala vestibuli
  • Cochlear duct (scala media)
  • Scala tympani
66
Q

Which of the chambers are part of the membranous labyrinth of the cochlear apparatus?

  • Scala vestibuli
  • Cochlear duct (scala media)
  • Scala tympani
A

The cochlear duct

The scala vestibuli and tympani are part of the bony labyrinth

  • Scala vestibuli
  • Cochlear duct (scala media)
  • Scala tympani
67
Q

At which site are the scala vestibuli and scala tympani continuous with each other?

A

At the apex of the cochlear - i.e., the helicotrema

68
Q

What is the modiolus?

A

The bony core of the cochlear

69
Q

Where are hair cells found in the cochlear apparatus?

A

The organ of Cortani in the cochlear duct (scala media)

70
Q

Hair cells convert fluid motion into neural stimuli. Which nerve carries the neural stimuli from the cochlear apparatus to the CNS?

A

The cochlear nerve (via the vestibulocochlear nerve - CN VIII)

71
Q

Where are cell bodies of the cochlear hair cells found?

A

In spiral ganglia in the modiolus

72
Q

Conductive hearing loss is due to problems in the external/middle/inner ear

A

External/middle

73
Q

Sensorineural hearing loss if due to problems in the external/middle/inner ear

A

Inner

74
Q

What structures pass through the internal acoustic meatus? (3)

A
  • Facial nerve (CN VII)
  • Vestibulocochlear nerve (CN VIII)
  • Labyrinthine artery + vein
75
Q

What are the 4 modalities of the facial nerve?

A
  1. Parasympathetic secretomotor supply to the lacrimal glands, minor glands of the nasal cavity, and the sublingual and submandibular glands
  2. Special sensation (taste) supply to the anterior 2/3rds of the tongue
  3. General sensation to the anterior 2/3rds of the tongue
  4. Somatic motor supply to the muscles of facial expression
76
Q

Where is the pterygopalatine ganglion located?

A

The pterygopalatine fossa (PPF) between the sphenoid bone and maxilla

77
Q

Which nerve supplies the posterior 1/3rd of the tongue?

A

CN IX (glossopharyngeal nerve)

78
Q

What is the pterygopalatine ganglion?

A

A parasympathetic ganglion in the neck that receives pre-ganglionic parasympathetic fibres from…

  • The greater petrosal nerve of the facial nerve (CN VII)
  • Maxillary division of the trigeminal nerve (CN V2)
79
Q

Describe the parasympathetic and sympathetic inputs to the pterygopalatine ganglion

A
  • The facial nerve (CN VII) runs through the facial canal in the temporal bone
  • The greater petrosal nerve (parasympathetic) arises from the facial nerve (CN VII) in the geniculate ganglion
  • It travels from the middle cranial fossa and joins the deep petrosal nerve (sympathetic) to form the vidian nerve of the pterygoid canal
  • The vidian nerve enters the pterygopalatine ganglion
80
Q

Where does the deep petrosal nerve come from?

A

The internal carotid artery

81
Q

What symptoms can facial nerve dysfunction present with?

A

Dry eyes, mucosa or mouth

Lack of taste in anterior 2/3rds of tongue

Facial paralysis

82
Q

When the vidian nerve enters the pterygopalatine ganglion, describe the route of the greater petrosal nerve

A
  • Greater petrosal nerve synapses in the PPG

- Post-synaptic parasympathetic fibres travel to glands in the nasal cavity, palate and pharynx

83
Q

When the vidian nerve enters the pterygopalatine ganglion, describe the route of the deep petrosal nerve

A

The deep petrosal nerve is already post-synaptic, so these post-synaptic sympathetic fibres pass straight through the PPG to supply sympathetic innervation to the vasculature of the nasal and oral mucosa