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MBBS2/ANATOMY~HEAD & NECK > Head & Neck special senses > Flashcards

Head & Neck special senses Flashcards

1
Q

whats the function of the eye

A

self-focus light

adjusts light intensity

converts light into electrical impulses interpreted by brain

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2
Q

where are orbits located

A

upper half of face below anterior cranial fossa and anterior to the middle cranial fossa

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3
Q

whats the bony orbit

A

a pyramidal bony cavity of facial skeleton

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4
Q

the apex of the bony orbit extends

A

posteromedially -towards optic cavity

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5
Q

what 7 bones contribute to the framework of each orbit

A

maxilla

zygomatic

frontal

ethmoid

lacrimal

sphenoid

palatine

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6
Q

the bony orbit is lined by

A

periorbita which is fascia sheath of the eye

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7
Q

the periorbita is continuous at

A

optic canal

superior orbital fissure

inferior orbital fissure

dural fascia

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8
Q

what are the contents of the orbit

A

eyeball

optic nerve

extra-ocular muscles

lacrimal apparatus

adipose tissue

fascia

nerves and vessels

conjunctival sac

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9
Q

the orbital margin is formed by what bones

A

frontal
maxillary
zygomatic

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10
Q

how many walls does the orbit have

A

4 and apex

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11
Q

the superior wall (roof) of the orbit is formed by

A

orbital part of the frontal bone which has lacrimal fossa with lacrimal gland

lesser wing of sphenoid near the apex

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12
Q

the medial wall ( paper thin wall) of the orbit is formed by

A

ethmoid bone
frontal bone
lacrimal bone
sphenoid bone (body)

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13
Q

medial wall of the orbit is indented by

A

lacrimal fossa for lacrimal sac

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14
Q

what separates the 2 medial walls of the orbit

A

ethmoid sinuses

nasal cavity

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15
Q

what forms the inferior wall (floor) of the orbit

A

maxilla bone at the orbital surface

part of zygomatic and palatine bones

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16
Q

the lateral wall of the orbit is formed by

A

frontal process of zygomatic bone

greater wing of sphenoid bone

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17
Q

where is the apex of the orbit

A

at optical canal in lesser wing of sphenoid b one, medial to superior orbital fissure

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18
Q

what can cause exophthalmos

A

fracture of the orbit

blowout fracture- where there is intra-orbital bleeding

periorbital ecchymosis-where blows to periorbital causes bleeding and swelling

orbital tumors

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19
Q

what do eyebrows do

A

provide shade and are a shield for perspiration

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20
Q

what are eyelids (palpebrae)

A

skin covered folds with tarsal plates made of connective tissue

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21
Q

what does levator palpebrae superioris muscle do and what innervates it

A

opens eye

occulomotor nerve

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22
Q

superior tarsal muscle portion is what and what innervates it

A

smooth muscle

post ganglion sympathetic fibers

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23
Q

what accounts for accumulation of fluid (blood) when injured during periorbital ecchymosis

A

thin layer of connective tissue and loose arrangement

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24
Q

whats the sensory innervation of the eyelids

A

supra-orbital, supra-trochlear, infra-trochlear, infra-orbital nerves (v2) which are terminal branches of the frontal nerve, which is the largest branch of the ophthalmic division of the trigeminal nerve

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25
Q

whats the motor innervation of the eyelids

A

branches of the :

facial nerve (CN VII) which innervates palpebral part of orbicularis oculi

oculomotor nerve (CN III) which innervates levator palpebral superioris

sympathetic fibers which innervate superior tarsal muscle

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26
Q

what is the canthus

A

the corner of the eye

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27
Q

what does the lacrimal caruncle make

A

eye sand at medial corner

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28
Q

what do tarsal glands make

A

oil to slow drying of canthus

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29
Q

eyelash has what gland at the hair follicule

A

ciliary gland

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30
Q

eyelashes are sensitive to

A

touch

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31
Q

what does the mucous membrane of the eye do

A

it coats the inner surface of the eyelid (palpebral part) and then folds back onto the surface of the eye (ocular part)

32
Q

what is the mucous membrane of the eye

A

a thin layer of connective tissue which is transparent

and shows blood vessels underneath (blood-shot eyes)

33
Q

what lines the mucous membrane of the eye

A

stratified columnar epithelium with goblet cells which secrete mucous to keep eyes moist

34
Q

why is vitamin A necessary for all epithelial secretions

A

because its lack leads to conjunctiva drying up and the formation of scaly eye

35
Q

lacrimal apparatus is involved in

A

production, movement and drainage of fluid on the surface of the eyeball

36
Q

the lacrimal apparatus is composed of

A

lacrimal glands

lacrimal duct (nasolacrimal duct)

tears

37
Q

describe the components of the lacrimal apparatus

A

lacrimal glands- which are superficial/lateral in orbit and produce tears

lacrimal duct- is in the medial corner of the eye and carries tears to the nasal cavity (is closed in newborns and usually opens by 1 yr)

tears- contain mucous, antibodies and lysozyme (anti-bacterial)

38
Q

whats the pathway for tears

A

they’re produced by the lacrimal gland~ then spread over eyeball~ then enter the lacrimal lake~ then Lacrimal canaliculi~ then lacrimal sac~ then nasolacrimal duct~ and out trough the inferior nasal meatus

39
Q

what are the 2 groups of muscles within the orbit

A

extrinsic muscles- which are involved in movement of the eyeball and raising upper eyelids

intrinsic muscles- which control the shape of the lens and size of the pupil

40
Q

extrinsic muscles of the eye include

A

levator palpebrae

superior rectus

inferior rectus

superior oblique

inferior oblique

medial rectus

lateral rectus

41
Q

what innervates the eye muscles

A

oculomotor

abducent

trochlear

42
Q

innervation of the muscles of the eye can be summarized as

A

SO4, LR6 and remainder 3 i.e.

Superior oblique is innervated by trochlea (CN IV)
Lateral rectus is innervated by abducens (CN VI)
The remaining 3 muscles are innervated by oculomotor nerve (CN III)

43
Q

what are the eye movements

A

elevation- moving pupil superiorly

depression-moving pupil inferiorly

abduction- moving the pupil laterally

adduction- moving the pupil medially

44
Q

whats intorsion (internal rotation) of the eye and what causes it

A

medial (inward) rotation of the upper pole of cornea

superior oblique and superior rectus

45
Q

whats extorsion (external rotation) of the eye and what causes it

A

lateral (outward) rotation of the superior pole of the cornea

inferior rectus and inferior oblique

46
Q

axis of each orbit is directed

A

slightly lateral

47
Q

axis of each eyeball is directed

A

anteriorly

48
Q

whats the origin and insertion of the levator palpebrae superioris muscle

A

lesser wing of sphenoid to insert at the anterior surface of the tarsal

49
Q

whats the function and innervation of the levator palpebrae superioris

A

elevation of upper eyelid

oculomotor nerve (CN III)

50
Q

superior tarsal muscle is what type of muscle

is innervated by

and does what

A

smooth muscle

post ganglion sympathetic fibers from superior cervical ganglion

maintains eyelid elevation

51
Q

loss of function of either levator palpebrae or superior tarsal muscle results in

A

ptosis or drooping of the upper eyelid

52
Q

loss of innervation of orbicularis oculi by facial nerve causes

A

inability to close the eye tightly and the lower eyelid droops away spilling tears

53
Q

loss of innervation of levator palpebral superioris by oculomotor nerve causes what

A

inability to open the upper eyelid voluntarily producing a complete ptosis

54
Q

loss of innervation of superior tarsal muscle by sympathetic fibers causes

A

constant partial ptosis

55
Q

what causes Horner’s syndrome

A

lesion e.g. tumor eroding the cervicothoracic ganglion which leads to sympathetic function in the head

56
Q

Horner’s syndrome is characterized by

A

pupillary constriction (miosis)- which is paralysis of the pupillary dilator muscle

partial ptosis- which is paralysis of the superior tarsal muscle

absence of ipsilateral sweating (loss of sweating of the face)

57
Q

where do the rectus muscles of the eye originate from

A

a common tendinous ring at the apex of the orbit

58
Q

where do the superior and inferior rectus muscles insert

A

anterior half of the eyeball - hence directed laterally

59
Q

what is the movement and innervation of the:
superior oblique

lateral rectus

medial rectus

superior rectus

inferior rectus

inferior oblique

A

depresses eye, turns medially- trochlear (CN IV)

turns laterally -abducens (CNVI)

turns medially- oculomotor (CN III)

elevates- oculomotor (CN III)

depresses eye- oculomotor (CN III)

elevates eye, turns laterally- oculomotor (CN III)

60
Q

what is strabismus

A

a vision disorder in which the eyes don’t properly align when looking at an object (the eye thats focused on an object can be altered)

61
Q

strabismus can be categorized by

A

the direction of the turned or misaligned eye i.e.

inward turning (esotropia)
outward turning (exotropia)
upward turning (hypertropia)
downward turning (hypotropia)
62
Q

what are the 3 layers of the eye

A

outer fibrous layer

middle vascular (pigmented) layer

inner layer

63
Q

a lesion at CN III will cause

A

complete ptosis (drooping of upper eyelid)

64
Q

the external white fibrous coat of the eyeball consists of

A

sclera and cornea

65
Q

whats the sclera

A

the white fibrous layer covering 5/6 of the eye

66
Q

whats the cornea

A

the transparent structure forming the anterior 1/6 of the outer coat

67
Q

the middle vascular pigmented coat of the eyeball consists of

A

the choroid
ciliary body
iris

68
Q

whats the choroid and its function

A

outer pigmented and inner vascular layer which invests 5/6 of the eye

it nourishes the retina and darkens the eye

69
Q

whats the ciliary body

A

the thickened portion of the vascular coat between the choroid and iris

70
Q

what does the ciliary body consist of

A

ciliary ring
ciliary processes
ciliary muscles

71
Q

whats the iris

A

the thin contractile circular pigmented diaphragm with central aperture pf the pupil

72
Q

the internal nervous coat consists of

A

retina - which is the outer pigmented inner nervous

73
Q

whats the posterior and anterior part of then internal nervous coat like

A

posterior part- photosensitive

anterior part- not photosensitive

74
Q

what does the optic disc (blind spot) consist of

A

optic nerve fibers formed by axons of ganglion cells which connect to rods and cones

75
Q

the optic disc has no

A

receptors hence is not photosensitive

MBBS2/ANATOMY~HEAD & NECK (13 decks)

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