Special Senses

Question 1

what is the structure and function of the sclera of the eye?

Answer 1

white of the eye covered by bulbar conjunctive
formed from fibrous and elastic tissue
allows contraction of eye, load bearing and maintains refractive status with the cornea

Question 2

what is the iris of the eye?

Answer 2

smooth muscle structure controlling pupil diameter

Question 3

what 2 muscles control the pupil diameter?

Answer 3

sphincter papillae (constriction)
dilator papillae (dilation)

Question 4

why is the cornea of the eye most used for transplants?

Answer 4

it’s avascular so it’s less likely to reject new tissue

Question 5

explain the outcome of the optic nerve when brain pressure increases

Answer 5

pressure travels along the optic nerve causing bulging of optic disk (papilloedema)

Question 6

what is keratoconus?

Answer 6

thinning of the cornea causing a cone shaped cornea and vision blurring

Question 7

what happens in the anterior and posterior chamber of the eye?

Answer 7

produces humerus fluid and circulates it between anterior and posterior to maintain eye pressure

Question 8

explain the function of the lens of the eye

Answer 8

helps focus visual info to the back of the retina

Question 9

describe the composition of the vitreous chamber

Answer 9

contains vitreous humour, a gel like structure
contains phagocytes to remove cell debris
composed of water/electrolytes
no blood vessels

Question 10

explain the function of the retina

Answer 10

interpretates black and white vision (rods) and coloured vision (cones)

Question 11

explain the journey of the impulses of vision from eye to brain

Answer 11

optic nerve -> optic chiasm -> optic tract -> radiation -> occipital lobe of brain

Question 12

where does tear production occur?

Answer 12

lacrimal gland

Question 13

what are the functions of tears?

Answer 13

lubricates movement
removes debris (washed across eye from lateral to medial)

Question 14

what are the 7 bones of the orbit?

Answer 14

frontal, sphenoid, zygomatic, palatine, ethmoid, lacrimal, maxilla

Question 15

what are the 3 sinal cavities?

Answer 15

orbital, nasal and oral cavities

Question 16

what are the 4 types of paranasal sinuses?

Answer 16

maxillary (under eyes)
frontal (forehead)
ethmoid/sphenoid (posterior to nose)

Question 17

what is the function of sinuses?

Answer 17

mucous circulation
contributes to sound resonance
reduces skull weight

Question 18

what is the function of extraocular muscles?

Answer 18

repsonsible for movement of the eye structures

Question 19

name the 7 extraocular muscles and which cranial nerve innervates it

Answer 19

levator palpebrae superioris (CN3)
superior rectus (CN3)
inferior rectus (CN3)
medial rectus (CN3)
lateral rectus (CN6)
superior oblique (CN4)
inferior oblique (CN3)

Question 20

what is the function of the levator palpebrae superioris muscle?

Answer 20

keeping upper eyelid open

Question 21

what is the function of the medial and lateral rectus muscles?

Answer 21

medial - adducts eyeball (towards nose)
lateral - abducts eyeball (away from nose)

Question 22

what is the function of the superior/inferior rectus muscles?

Answer 22

superior - elevation of eyeball (up/towards nose)
inferior - depression of eyeball (down/towards nose)

Question 23

what is the function of the superior/inferior oblique muscles?

Answer 23

superior - depression of eyeball (down/away from nose)
inferior - elevation of eyeball (up/away from nose)

Question 24

how does the nose control the features of the air entering?

Answer 24

rich/superficial blood supply to warm air
mucous provides moisture to air
mucous and hair traps patricles to filter air

Question 25

what is the purpose of the olfactory nerve?

Answer 25

converts chemical energy to electrical energy located in superior surface of nasal cavity

Question 26

what are the folds in the nasal cavity called and what is their function?

Answer 26

conchae - increase surface area and increase chance of olfactory exposure

Question 27

name 2 unusual characteristics of the tongue muscle

Answer 27

boneless contains both intrinsic and extrinsic muscle

Question 28

what are the 2 parts of the tongue?

Answer 28

oral - at front pharyngeal - at back

Question 29

what are the sublingual glands?

Answer 29

salivary glands producing mucous like secretion

Question 30

name the 2 surfaces within the mouth

Answer 30

buccal - cheek lingual - inner gums

Question 31

what is the muscle at the bottom of the mouth?

Answer 31

mylohyoid muscle

Question 32

name the 6 structures of the tongue

Answer 32

foramen caecum terminal sulcus foliate papillae fungiform papillae vallate papillae filiform papillae

Question 33

name the nerve innervating the front 2/3 of the tongue and the 2 nerve branches which combine to form it

Answer 33

lingual nerve formed from chorda tympani (from CN7) and 3rd branch of CN5

Question 34

what functions do cranial nerves 9 and 12 have in the back 1/3 of the tongue

Answer 34

CN9 carries taste and sensation CN12 allows motor control

Question 35

what strucures are found in the external ear?

Answer 35

ear drum/tympanic membrane

Question 36

what structures are present in the middle ear?

Answer 36

malleus/incus/stapes bones oval window

Question 37

what features are found in the inner ear?

Answer 37

semicircular canal cochlear

Question 38

what cranial nerves are found in the internal acoustic meatus'?

Answer 38

CN7 and CN8

Question 39

what are the 2 portions of the temporal bone?

Answer 39

petrous and squamous

Question 40

what is the function of the ossicles?

Answer 40

transmit vibrations through middle ear

Question 41

what is found in the lateral wall of the middle ear?

Answer 41

tympanic membrane (ear drum)

Question 42

what is found in the medial wall of the middle ear?

Answer 42

vestibular window - opening into vestibule of inner ear, closed by stapes base cochlear window - opening into cochlear portion of inner ear

Question 43

what is the function of the cochlea?

Answer 43

sound amplification, conversion from vibration to electrical signal, signal transferred through CN8

Question 44

what is the function of the semicircular canals?

Answer 44

balance, innervated by CN8 (vestibular part)

Question 45

what does the auditory (eustachian) tube do?

Answer 45

links middle ear with pharynx to maintain pressure

Question 46

explain sound waves

Answer 46

vibration of a medium spreads out as a pressure wave

Question 47

name the measurements for different aspects of sound

Answer 47

frequency - hertz intensity (loudness) - decibels

Question 48

name the basic structures in each section of the ear

Answer 48

outer - pinna, canal middle - tympanic membrane, ossicles inner - cochlea, vestibules

Question 49

what is the function of the pinna?

Answer 49

amplifies & filters incoming sounds (directional dependant)

Question 50

how does the middle ear overcome impedance mismatch?

Answer 50

collects sound over large area (tympanic membrane) converts air vibration into bone vibration (dense) concentrates energy onto small area (oval window) uses bone as piston to transfer energy in fluid

Question 51

what is the main advantage of a 3 ossicle system?

Answer 51

increased high frequency range

Question 52

what are the 2 protective muscles of the middle ear?

Answer 52

stapedius reflex and tensor tympani

Question 53

when does the eustachian tube open?

Answer 53

during swallowing and valsalva (ear popping)

Question 54

name some reasons for conductive hearing loss

Answer 54

canal - wax, foreign body tympanic membrane - perforation ossicles - congenital fusion, infection damage middle ear - fluid instead of air

Question 55

what structural feature of the ear allows amplification?

Answer 55

the tympanic membrane being much larger than oval window

Question 56

how do vibrations enter the cochlea?

Answer 56

oval window faces into vestibule vestibule contains sensory epithelia for saccule/utricle vestibule leads into scala vestibuli (upper cochlear duct)

Question 57

explain the structure of the organ of corti

Answer 57

sits on basilar membrane, connected to auditory nerve fibres, contains spiral ganglion

Question 58

how does the basilar membrane contribute to frequency analysis?

Answer 58

stiff and light at one end but flexible and heavy at another end

Question 59

explain the hair cell structure in the cochlea

Answer 59

hair cells of epithelial origin (resembling stomach cells) stereocilia form bundles at atypical pole of hair cell arranged from shortest to tallest

Question 60

explain how stereocilia contribute to membrane polarisation

Answer 60

if stereocilia pushes towards tallest hair cells -> depolarisation and K+ channels open into endolymph vice versa

Question 61

what do inner hair cells do?

Answer 61

turn vibrations into neural signals

Question 62

name some things that in the inner ear that can cause hearing loss

Answer 62

loss of inner hair cells (no signal to brain) loss of outer hair cells (basilar vibration impaired)

Question 63

what fluid is contained in the scala media and what is unique about it?

Answer 63

endolymph - high potassium and low sodium

Question 64

what fluid is contained in the scala vestibuli/tympani?

Answer 64

perilymph

Question 65

what is the function of the stria vascularis?

Answer 65

regulates ionic and metabolic functions of scala media

Question 66

how do outer hair cells (OHCs) amplify vibration?

Answer 66

when stimulated (basilar membrane movement) they change shape/stiffness feeding energy into BM which acts as an amplifier (increases BM total vibration)

Question 67

how does the nose conduct quiet breathing?

Answer 67

laminar airflow over the inferior turbinate

Question 68

what does sniffing do in terms of odorants?

Answer 68

mixes air and sends odorants towards roof of nose towards olfactory receptors

Question 69

explain the function of odorants being detected by olfactory receptors

Answer 69

odorant molecules dissolved in nasal mucous which is then detected by rhodopsin

Question 70

what feature of odorants and receptors have that allows smell identification?

Answer 70

odorants can stimulate more than one receptor and receptors can respond to more than 1 odorant

Question 71

where does the olfactory nerve project to?

Answer 71

amygdala, hippocampus, parahippocampal gyrus

Question 72

what surgeries can loss of taste be a side effect of?

Answer 72

ear/salivary gland surgeries