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Medicine phase 1 > week 12 - special senses > Flashcards

week 12 - special senses Flashcards

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1
Q

structural components of the eye

A 
sclera
pupil
iris 
cornea
optic nerve
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2
Q

structure of sclera

A

White of the eye, fibrous and elastic tissue, outer layer of eye - allows for the contrast of the eye to determine where a person/animal is looking

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3
Q

structure of the pupil

A

middle of the iris
wider in dark
smaller in light

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4
Q

structure of iris

A

smooth muscle structure which controls the diameter of the pupil via two muscles - sphincter pupillae and dilator pupillae

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5
Q

structure of cornea

A

avascular

common for use in transplant as it cannot reject the tissue due to blood supply as it does not have one

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6
Q

optic nerve structure

A

appears as a solid white structure roughly in the middle of the retina
surrounded by the meningeal layers of the brain, any pressure increases intracranially (eg bleed, tumour or other space occupying lesion) will be transmitted along the nerve and causes bulging of the optic disc - This is called papilloedema and requires investigation as to the cause

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7
Q

what is keratoconus

A

thinning of the cornea resulting in a coning shape and can cause blurring and double vision of the eyes
Surgery may have to be done in more severe cases of a corneal transplant

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8
Q

what is aqueous humour

A

produced in anterior and posterior chambers of the eye from the ciliary bodies
maintains the pressure inside the eye, provides nutrients to eye and protects the eye

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9
Q

what is vitreous humour

A

a gel which occupies the space between the lens anteriorly and the retina posteriorly
mainly contains phagocytes to remove cell debris and is mainly water with no blood vessels

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10
Q

describe the retina

A

the light sensitive layer of tissue of the eye and where the rods and cones are for black and white and colour vision respectively

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11
Q

pathway of nerve fibres in eye

A
  • Visual input comes through pupil -> vitreous humour -> retina -> optic nerves -> optic tract -> optic chiasm -> optic tract -> optic radiation -> occipital lobe
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12
Q

where are tears proudced

A

lacrimal gland

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13
Q

function of tears

A

lubricates movement

removes debris - debris moves from lateral to medial direction into nose

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14
Q

why does your nose run when you cry

A

nasolacrimal duct (in nasolacrimal canal) takes tears from lacrimal gland to nasal cavity

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15
Q

7 bones of the orbit

A 
frontal 
sphenoid
zygomatic
palatine
ethmoid
lacrimal
maxilla
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16
Q

where are the paranasal sinuses

A

maxillary - under eyes
frontal - forehead
ethmoid - posterior to nose
sphenoid - posterior to nose

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17
Q

function of paranasal sinuses

A

reduces weight of skull
allows circulation of mucous
contributes to resonance of sounds

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18
Q

which cranial nerves control eye movement

A

III
IV
VI

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19
Q

7 extraocular muscles and their movements

A

levator palpebrae superioris - keeping upper eyelid open
Superior rectus – elevation of eyeball (also adduction of eyeball and medial rotation)
Inferior rectus – depression of eyeball (adduction and lateral rotation)
Medial rectus – Adducts the eyeball
Lateral rectus – Abducts the eyeball
Superior oblique – depression of eyeball, abduction and medial rotation
Inferior oblique – Elevation, abduction and lateral rotation of the eyeball

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20
Q

which eye nerves supply which muscles

A

Trochlear nerve only supplies superior oblique
Oculomotor nerve – inferior oblique, superior rectus, medial rectus, inferior rectus
Abducent nerve – lateral rectus

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21
Q

how structure of nose relates to its function

A 
incoming air is warmed, humidified, filtered
nose does this best due to:
rich, superficial blood supply,
mucous provides moisture
mucous and hairs trap particles
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22
Q

describe the location of the cribriform plate

A

The olfactory bulb, part of the brain, lies on the superior surface of the cribriform plate, above the nasal cavity
Branches of the olfactory nerve run through the cribriform plate to provide special sensory innervation to the nose

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23
Q

conchae in the nasal cavity

A

increase surface area

increase chance of olfactory exposure

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24
Q

innervation to tongue

A

CN IX - taste and sensation from posterior 1/3
CN XII - motor control of most tongue muscles
lingual nerve - carries axons from CN V and VII for taste and sensation in anterior 2/3

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25
describe the surfaces in the mouth
buccal surface - side of the mouth where the surface is towards the cheeks as a surface of the teeth lingual surface - faces the tongue as a surface of tongue floor of mouth - mylohyoid muscle and overlying stratified squamous epithelium
26
epiglottis
elastic cartilage which helps close over the trachea during swallowing
27
describe the ossicles in ear
malleus - attached to tympanic membrane incus stapes they transmit vibrations through middle ear
28
what is the oval/vestibular window
opening into the vestibule of inner ear | closed by base of stapes
29
what is the cochlear/round window
opening into the cochlear portion of inner ear
30
tympanic cavity contains...
tympanic membrane vestibular/oval window cochlear/round window
31
what is the helicotrema
the location where the tympanic duct and the vestibular duct merge, at the apex of the cochlea
32
what is Reissner's membrane
separates the vestibular duct (scala vestibuli) from the cochlear duct (scala media)
33
function of cochlea
sound amplification conversion from vibration to electrical signal signal transmitted via cochlear part of CN VII
34
function of semicircular canals
balance | vestibular part of CN VIII
35
CN in nose
CN I
36
CN in ears
CN VIII
37
CN in eyes
CN II for vision | CN III IV VI for eye movements
38
what is sound
changes in pressure over time - spreads out as a wave of pressure from the source Sound will dissipate through any medium as long as the particles in that medium can vibrate
39
high pitch
high frequency low wavelength
40
intensity/loudness
amount of energy/strength of vibrations - height of wave
41
range of hearing for a young human adult
20-20,0000 Hz
42
inner ear parts
cochlea and vestibule
43
middle ear parts
tympanic membrane ossicles eustachian tube
44
outer ear parts
pinna - amplifies and filters incoming sounds | ear canal - has hairs and wax on outer third
45
mechanisms that amplify sound in middle ear
difference in size between tympanic membrane and oval window | lever action - ossicles act as little levers adding a small amount of amplification
46
why does the middle ear amplify sound
transmission of sound from air to fluid-filled inner ear is inefficient due to impedance mismatch
47
branchial arches in ear
First arch turns into mandible which gives rise to malleus and incus Second arch gives rise to stapes
48
describe the protective muscles in the middle ear
stapedius reflex and tensor tympani they contract when ear is exposed to very loud sounds - there to stiffen the stapes so it does not vibrate and damage cochlea
49
structure of eustachian tube
connects nasopharynx to middle ear | lined with mucosa
50
function of eustachian tube
Keeps the air pressure in the middle ear space the same as the ambient atmospheric pressure - This is important to enable the tympanic membrane to vibrate
51
describe conductive hearing loss
sound does not reach cochlea - inner ear still working but sound does not reach there caused by: • Ear canal – wax, foreign body, congenital atresia • Tympanic membrane – perforation • Ossicles – congenital fusion, damage from infection • Middle ear space – fluid instead of air
52
describe the vestibular apparatus
contains sensory structures for balance and head movements utricle and saccule which are there for static position semicircular canals are there for rotatory acceleration in three planes
53
describe the scala media
contains endolymph
54
where is perilymph
scala vestibuli and scala tympani
55
structure of organ of corti
has a basilar membrane which the the hair cells sit on tectorial membrane covers the hair cells one row of inner hair cells and 3 rows of outer hair cells
56
how does the organ of corti work
sound vibrations in scala vestibuli and scala tympani set up vibrations in basilar membrane inner hair cells pick up vibrations on basilar membrane and send neural impulses along auditory nerve outer hair cells are motile and change shape and stiffness when stimulated by the vibrations - acts as an amplifier to increase amount of vibration as BM vibrates, stereocilia are bet against tectorial membrane - opens an ion channel - hair cell membrane is depolarised and NTs are released
57
describe hair cell depolarisation and hyperpolarisation
tallest cilium is the kinocilium on hair cell kinocilium moves away from sterocilia causing depolarisation kinocilium moves towards sterocilium causing hyperpolarisation
58
describe sensorineural hearing loss
the root cause lies in the inner ear or sensory organ (cochlea and associated structures) or the vestibulocochlear nerve
59
loss of inner hair cells
no signal to brain | loss of hearing
60
loss of outer hair cells
basilar vibration is insufficiently amplified some loss of hearing loss of discrimination - can hear speech but not understand it
61
describe the travel of an impulse generated by a sound wave
first order neurons in spiral ganglion of the cochlea -> CN VIII -> synapse on juction of medulla and pons -> pons -> midbrain -> thalamus -> cortex -> temporal lobe
62
what is the auditory nerve
one of two parts of CN VIII
63
describe the anterior 2/3 of tongue
innervated by CN V and VII | tuberculum impar is the midline
64
describe the tongue muscles
genioglossus, hyoglossus and styloglossus suspended from mandible, hyoid and styloid bones muscles work with palatoglossus to move tongue
65
function of filiform papillae
rough surface of tongue for manipulation of food
66
where are taste buds
scattered across tongue in fungiform papillae
67
5 tastes and where they come from
``` sour (acid, H+) salty (Na+) sweet (glucose) bitter (coffee, beer, quinine, blue cheese, olives) savoury/umami (glutamate) ```
68
chorda tympani in tongue
branch of the facial nerve that originates from the taste buds in the front of the tongue, runs through the middle ear, and carries taste messages to the brain
69
pathway of nerve impulses caused by taste
taste runs along lingual nerve and leave in chorda tympani which runs through middle ear to join facial nerve - runs with facial nerve to brainstem
70
lingual nerve
branch of CN V (trigeminal)
71
turbinates on nose
projections from either side of the nose with thick vascular mucosa to warm and humidify the air
72
pathway of smell
odorant molecules in air dissolve in nasal mucus odour receptor cells are then stimulated and axons pass through the little holes in cribiform plate up into olphactory bulb
73
describe olfactory receptors
exist on dendrites of receptor cells | each receptor responds to more than one odourant and each odourant stimulates more than one receptor
74
where does CN I project to
amygdala, hippocampus, parahippocampal gyrus
75
what is congenital anosmia
lifelong inability to smell | can be assoicated with kallmans syndrome
76
causes of anosmia
``` base of skull fracture covid 19 brain tumour early sign of Alzheimer’s, Parkinson’s, MS rhinosinusitis ```

Medicine phase 1 (14 decks)

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