eye and ear SDL

Question 1

what strutures does light pass through to reach the retinal photoreceptors

Answer 1

cornea, aqueous humour, lens, vitrous jelly, fovea

Question 2

what and where is the conjunctiva and function

Answer 2

thin membrane, coats the inside of the eyelids - lubricates the eye, involved in immune system (passively)

Question 3

function of sclera

Answer 3

attachment for muscles, protection from injury

Question 4

function of iris

Answer 4

controls the amount of light entering eye

Question 5

what is the nerve supply to the sphincter pupillae muscle

Answer 5

CN3

Question 6

what does the constriction of the ciliary body do?

Answer 6

lens becomes more rounded and powerful

Question 7

what are cataracts

Answer 7

clouding of the lens

Question 8

Other than Lens control what else is the ciliary body involved with>

Answer 8

production of aqueous humour

Question 9

what does aqueous humour do?

Answer 9

helps to maintain shape or cornea, and refractive properties of the eye

Question 10

what is glaucoma

Answer 10

progressive optic neropathy cause by problems with drainage of aqueous humour

Question 11

what are the functions of the choroid layer of the eyeball

Answer 11

provide o2 and nutrients to the outer later of retina

limit uncontrolled reflection in the eye

Question 12

what is contained in the retina

Answer 12

outer pigment cell layer - single layer of cuboidal epithelial cells with melanin filled microvilli extending from inner surface
multi layered neural retina

Question 13

where do the axons of the retinal ganglion converge?

Answer 13

optic disk/papilla - then turn outwards to form optic nerve

Question 14

what is papilloedema

Answer 14

optic disk swelling caused by increased intracranial pressure

Question 15

causes of papilloeadma

Answer 15

epidural tumour, extradural tumour, increased CSF, hydrocephalus, craniosynostosis

Question 16

where is the macula lutea

Answer 16

yellow pigmented zone lateral to the optic disk - in the centre is the FOVEA

Question 17

how is the fovea specialised for visual activity

Answer 17

high density of cones

Question 18

where do the blood vessels that supply the retinal cells lie

Answer 18

choroid - continuous with iris and ciliary body anteriorly

Question 19

what is a detached retina

Answer 19

retina becomes detached from choroid - risk of permanent visual damage

Question 20

What is the function of - Tympanic Membrane

Answer 20

sound waves –> ossicles

focuses sound

Question 21

What is the function of - ossicles

Answer 21

lever arm factor 1.3 - transfer from air to liquid form

Question 22

What is the function of - oval window

Answer 22

14 foldd smaller than tympanic membrane - pressure gain of 18.1 x

Question 23

What is the function of - round window

Answer 23

vibrates in anti phase to the oval window to allow liquid to move

Question 24

What is the function of - auditory tube

Answer 24

connects middle to nasopharanx to allow pressure to remain constant with external conditions

Question 25

what is the external auditory canal lined by

Answer 25

ear wax producing skin

Question 26

how does ear wax move down the canal and what is it made of

Answer 26

jaw movements secretions of cerminous and sebaceous glands, skin cells and hair, long chain fatty acids, alcohols, squalene and cholesterol

Question 27

what is the function of the chorda tympani

Answer 27

special sensory fibres to anterior 2/3 of tongue | presynaptic parasympathetic fibres to submandibular ganglion

Question 28

what is the middle ear

Answer 28

air filled chamber, containing ossicles, lined by respiratory epithelium

Question 29

what connects the middle ear to the nasopharynx

Answer 29

eustachian tube

Question 30

what connects the middle ear posteriorly to the mastoid air cells

Answer 30

mastoid antrum

Question 31

what are complications of a middle ear infection

Answer 31

meningitis, sigmoid sinus thromobis and brain abscess | due to direct expansion, thrombophlebitis, hematogenous dissemination

Question 32

why is facial nerve damage a potential complications of middle ear infection

Answer 32

formation of cholesteatoma (inc in keratinising squamous cells in the middle ear) can damage CNVII

Question 33

Tensor Tympani - nerve supply, function

Answer 33

Tensor Tympani Nerve CNVIII | dampens noise caused by chewing tenses the tympanic membrane to dampen vibration in ossicles

Question 34

Stapedius Muscle *smallest in body - nerve supply, function

Answer 34

Nerve to Strapedius - CNII | Stops excessive movement of Stapes, helps control amplitude of sound waves

Question 35

where is the inner ear

Answer 35

cavity within the Petrous temporal bone

Question 36

what is the fluid in the inner ear called

Answer 36

perilymph

Question 37

what is the membranous labyrinth

Answer 37

a epithelial sac - filled with endolymph

Question 38

3 sensory receptors in the wall of the membranous labyrinth

Answer 38

maculae - vestibular receptor christae ampullaris - vestibular receptor spiral organ (organ of Corti) - auditory receptors

Question 39

where is the maculae located in the membranous labyrinth

Answer 39

utricle and saccule of vestibule

Question 40

the Maculae are involved with what type of sensory info?

Answer 40

regarding the position of the head in space - important for balance

Question 41

where in the membranous labyrinth are the Chrisae Ampullaris located

Answer 41

end of semicircular canal - arise for vestuble

Question 42

what do the christae ampullaris do?

Answer 42

give sensory info about the direction and speed of movement of the head

Question 43

what can injury to peripheral vestibular system cause?

Answer 43

nystagmus and vertigo

Question 44

what is nystagmus

Answer 44

involuntary eye movement

Question 45

what is the organ of corti

Answer 45

specalised region of the wall of the cochlear duct within the snail-shell shaped bony choclea

Question 46

what does the bony cochlea and enclosed cochlear duct contain

Answer 46

after spirallingg 2.5 times round central axis of the bone, the central region encloses the spiral ganglion made up of cell bodies from 1st order auditory neurones

Question 47

explain how the organ of corti works?

Answer 47

Fluid movement in the inner ear caused the basilar membrane to vibrate points of the basilar membrane vibrates maximally in response to sound of a certain frequency vibration of basilar membrane cause hairs (sterecilia) to deform against overlying gelatinous tectorial membrane causes depolarisation of sensory hair cells - generates action potential

Question 48

where is high frequency sound maximally responded to

Answer 48

base of cochlea

Question 49

where is low frequency sound maximally responded to

Answer 49

apex of membrane

Question 50

where are the cell bodies of the sensory fibres that contact hair cells

Answer 50

in the spiral cochlea ganglion - found in the models (central axis) of the cochlea

Question 51

what crania nerve do these first order sensoory fibres join and where does the nerve enter the brainstem

Answer 51

vestibulocochlear (CNVIII) | pontine medulla junction