Head and Neck, Session 5 Flashcards Preview

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Flashcards in Head and Neck, Session 5 Deck (85):
1

what is at the apex of the orbit?

foramen= optic canal

2

in addition to the optic canal, what permits passage of nerves into the orbit?

superior and inferior orbital fissures

3

protective mechanisms of front of eye?

lacrimal gland
eyelids

4

via which 2 muscles does movement of eyelids occur?

orbicularis oculi
levator palpebrae superioris

5

function of orbit?

affords protection of eyeball and its muscles, nerves, vessels and most of lacrimal apparatus

6

what forms the fascial sheath of the eyeball?

periosteum (periorbita) lining bones of orbit

7

where is the periorbita continuous with the periosteal layer of dura mater?

at optic canal and supraorbital fissure

8

what are the eyelids lined by in the inner surface?

conjunctiva

9

how are the eyelids strengthened?

tarsal plates- dense bands of CT

10

how are the eyelids prevented from sticking together when they close?

secretion from tarsal glands contained in tarsal plates, which lubricates edges of eyelids

11

what does the lacrimal apparatus consist of?

lacrimal glands, lacrimal ducts, lacrimal canaliculi

12

what is a blowout fracture?

indirect trauma or injury that displaces orbital contents

13

when does a stye form in the eyelid?

when ducts of ciliary glands become obstructed

14

facial nerve is damaged, how does this affect eye protection?

protection lost as loss of orbicularis oculi function which allows eyelids to close, so loss of protective blinking
so cornea becomes dry and is left unprotected from dust and other particulate mateial
eyeball irritation causes excessive tear formation

15

how is attachment of extraocular muscles provided?

by outer protective layer of eyeball, comprising sclera and cornea, which is fibrous

16

what does middle coat of eyeball comprise?

iris, choroid and ciliary body

17

what is the inner layer of the eyeball?

retina, consisting of optic and non-visual parts

18

what does the choroid lie between?

the sclera and the retina

19

what does the choroid terminate as anteriorly?

ciliary body

20

what does ciliary body connect?

the choroids with the iris

21

where is the aq humour that fills the chambers of the eye secreted from?

the ciliary body

22

where is the anterior chamber of the eyeball located?

between cornea and iris

23

where is posterior chamber of eyeball located?

between iris and ciliary body and lens

24

what name is given to the central aperture of the iris?

pupil

25

how is the lens attached to the ciliary body?

by suspensory ligaments

26

what does the cavity behind the lens contain?

vitreous humor- supports lens and holds retina in place

27

what is the area of most acute vision?

the fovea centralis

28

arterial supply of retina?

central artery of the retina

29

how would damage to opthalmic division of trigeminal nerve affect the eye?

cornea would be rendered vulnerable to foreign objects

30

what is opacity of lens known as?

cataracts

31

2 layers of optic retina?

neural layer- light-receptive
pigmented layer

32

where does optic nerve enter eyeball?

at optic disc

33

what is a detached retina?

separated neural and pigmented layers of retina, may occur with blow to the eye

34

what are the muscles of the orbit?

levator palpebrae superioris
superior, inferior, medial and lateral recti
superior and inferior oblique

all supplied by oculomotor except superior oblique- trochlear, and lateral rectus- abducent

35

where do recti muscle arise from?

common tendinous ring- fibrous cuff

36

where do opthalmic veins drain?

into cavernous sinus

37

result of blockage of central retinal veins?

gradual loss of vision

38

what may cause sudden painless loss of vision?

retinal vascular occlusion
retinal detachment

39

when is gradual painless loss of vision commonly seen?

in chronic simple glaucoma

40

when is pain in the eye seen with blinking?

corneal abrasions with presence of FBs in eye

41

why are diseases of cornea associated with significant pain?

rich nerve supply of cornea

42

when is pain on motion of eye seen?

optic neuritis

43

how may severe coughing spells and recurrent vomiting damage the eye?

can cause a conjunctival haemorrhage

44

how might a patient try and relieve diplopia?

by closing 1 eye or compensatory head posture

45

which bones form the roof of the orbit?

frontal and sphenoid

46

which bones form floor of orbit?

maxilla, zygomatic (and palatine)

47

which bones form medial wall of orbit?

ethmoid, maxilla and lacrimal bones

48

which bones form lateral wall of orbit?

zygomatic and sphenoid

49

within which bone is the optic canal?

sphenoid

50

which structures pass through superior orbital fissure?

lacrimal nerve
frontal nerve
trochlear nerve
superior branch of oculomotor nerve
nasociliary nerve
inferior branch of oculomotor nerve
abducent nerve
opthalmic veins
sympathetic nerves

51

why does a blockage of the central artery of the retina cause instant and total blindness?

terminal branches of artery are end arteries, so provide only source of blood to internal aspect of retina

52

what is inside each cavernous sinus?

internal carotid artery with its small branches, surrounded by carotid plexus of sympathetic nerves, and abduncent nerve. Oculomotor and trochlear nerves, plus 2 of the 3 divisions of trigeminal, embedded in lateral wall.
heat exchange occurs to conserve energy or cool arterial blood *similar to pampiniform venous plexus in spermatic cord

53

what is the 1st sign of compression of oculomotor nerve?

ipsilateral slowness of pupillary response to light- pupils slow to constrict

54

where does CNI leave skull base?

cribiform plate of ethmoid bone

55

where does CNII leave skull base?

optic canal

56

where does CNsIII, IV, Vi and VI leave skull base?

superior orbital fissure

57

where does CNVii leave skull base?

foramen rotundum

58

where does CNViii leave skull base?

foramen ovale

59

where do CNsIX, X and XI leave skull base?

jugular foramen

60

where does CNXII leave skull base?

hypoglossal canal

61

name of disease in which lacrimal fluid not produced, in association with xerostomia?

sjrogens syndrome

62

which sinuses may be involved in medial wall of orbit fracture?

ethmoidal and sphenoidal

63

which sinuses may be involved in inferior wall of orbit fracture?

maxillary

64

how can the superior wall of the orbit be penetrated?

sharp object may pass through it and enter frontal lobe of brain

65

which muscle lies on top of the superior rectus muscle?

levator palpebrae superioris

66

how is the superior oblique muscle tested for?

ask patient to look inwards and dwards e.g. reading a book

67

3 actions of superior oblique?

medial rotation
depression
abduction

68

arteries of orbit?

opthalmic- branch of internal carotid, via optic canal, gives rise to central artery of retina
infraorbital- branch of external carotid

69

veins of orbit?

S and I opthalmic, exit via superior orbital fissure to cavernous sinus
central vein of retina, either directly to cavernous sinus or joins opthalmic veins
INFECTION can spread to brain via veins

70

name given to opening created by retraction of upper and lower eyelids?

palpebral fissure

71

in what 4 ways is the blinking reflex triggered?

drying of cornea: blinking moistens cornea, lacrimal fluid
irritation of cornea: blinking to shut eye and prevent entry of irritants
touching of cornea: perceived as pain, triggering eye closure
sight of on-coming irritant to eye: in anticipation of painful stimuli irritating sensory apparatus

72

origin of central artery of retina?

opthalmic artery- branch of ICA

73

composition of lacrimal fluid?

water- from lacrimal glands
mucins- from conjuctival goblet cells
oil- from mebomian glands which forms a barrier against vapourisation of lacrimal fluid, so blink less
bactericidal enzymes + antibodies- from lacrimal gland
fluid swept across surface of eye on blinking, and keeps cornea moist and healthy
infermomedial drainage
provides some nutrients and dissolved O2 to cornea

74

where does the lacrimal gland lie?

in a fossa on superolateral part of orbit

75

what happens to lacrimal fluid formation if eyelids prevented from closing properly?

protective blinking lost so cornea becomes dry and left unprotected from dust and particulate material, so irritation of eyeball causes excessive tear formation

76

what happens to the eye if orbicularis oculi is paralysed?

failure to close
also paralysis of LPS as inserts into OO
failure to blink
failure to spread lacrimal fluid
likelihood of eye infection, can lead to blindness
can use eyedrops

77

what is harlequin syndrome?*

presentation of hemifacial sweating and flushin on unaffected side due to sympathectomy

78

how does aq humor drain?

via trabecular meshwork into scleral venous sinus

79

ciliary muscle function in near vision?

contracts in accomodation- lens made more convex under PSNS activity via CN III

80

what is mydriasis?

dilation of pupil, result of reduced PNS activity to sphincter pupillae, or increases SNS to dilator, may be due to raised IC pressure

81

what might a patient with a detached retina complain of?

flashes of light or specks floating in front of the eye

82

what is a coloboma?

an absence of a section of the iris

83

what is a hyphema?

Haemorrhage within the anterior chamber of the eyeball usually results from blunt force trauma to the eyeball.

84

what may cause unilateral exophthalmos?

aneurysm
haematoma

85

why can an increase in CSF pressure cause blindness?

may compress optic nerve as nerve surrounded by meninges with CSF in subarachnoid space, and this can then compress blood vessels supplying retina as run within optic nerve