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Regional Anatomy > The orbit > Flashcards

The orbit Flashcards

1
Q

what bone forms the roof of the orbit

A

frontal bone

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2
Q

the frontal bone forms what parts of the orbit

A

roof, parts of medial and parts of lateral walls

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3
Q

the frontal bone has a notch for what

A

supraorbital nerve and artery

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4
Q

what deflects blows to the face away from the eyes

A

supraorbital ridge

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5
Q

what bone forms part of the lateral wall of the orbit (not frontal)

A

zygoma

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6
Q

what bone forms a large part of the floor of the orbit

A

maxilla

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7
Q

what bone forms the infraorbital foramen

A

maxilla

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8
Q

what passes through the infraorbital foramen

A

infraorbital branch of CNV2 exits skull via infraorbital foramen

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9
Q

what bone forms the naso-lacrimal duct

A

lacrimal

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10
Q

what is the purpose of the naso-lacrimal duct

A

carries excess lacrimal fluid (tears) into the nasal cavity

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11
Q

what bone forms part of the medial wall of the orbit but also contributes to the nasal cavities

A

ethmoid bone

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12
Q

what is the butterfly shaped bone in the skull called

A

sphenoid bone

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13
Q

what foramina does the sphenoid bone form

A

optic canal
superior orbital fissure
contributes to the inferior orbital fissure

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14
Q

what passes through the inferior orbital fissure

A

ophthalmic veins

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15
Q

what nerves pass through the superior orbital fissure

A

CN III
CN IV
CN V
CN VI

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16
Q

there is a tiny contribution from what in wall of inferior orbital fissure

A

palatine

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17
Q

what is contained in the orbit

A

eyeball
fat and connective tissue
extra-ocular muscles
nerves
blood vessels

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18
Q

the orbital contents are protected anteriorly by what

A

orbital septum composed of strong connective tissue

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19
Q

the corners of the eyelid are supported by what

A

medial and lateral palpebral ligaments

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20
Q

what is the function of the tarsal plates

A

dense connective tissue which support eyelid. also contain glands that release oily fluid and watery secretions to lubricate the surface of the eye

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21
Q

what is the function of the check ligaments

A

restrict the movements of the extra-ocular muscles - restrict medial and lateral recti

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22
Q

what is the function of the suspensory ligament of the eye

A

supports the position of the eyeball within the orbit

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23
Q

what forms the outer coat of the eyeball

A

cornea and sclera - fibrous layers

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24
Q

what is the middle layer of the eyeball

A

vascular layer - iris, ciliary body and choroid

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25
Q

what is the inner layer of the eye

A

retina

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26
Q

what is the blind spot

A

area where the optic nerve leaves the eye so it is void of rods and cones

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27
Q

what is the area of the retina that is rich in both rods and cones

A

macula lutea (fovea)

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28
Q

where is the anterior chamber of the eye

A

between the lens and the cornea

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29
Q

what is in the anterior chamber of the eye

A

aqueous humor - thin fluid

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30
Q

what makes aqueous humor

A

cells of the ciliary body

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31
Q

how is aqueous humour recycled

A

recycled back into veins at the junction of the cornea and sclera
(corneo-scleral junction - canal of Schlemm)

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32
Q

what fills the posterior chamber of the eye

A

vitreous humour (gel)

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33
Q

what is the function of the vitreous humor

A

supports the retina by gently pressing it against the choroid below

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34
Q

the choroid has what

A

blood vessels that supply the retina

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35
Q

what are the 2 types of muscles associated with the eyeball

A

extra-ocular (Extrinsic) muscles
intra-ocular (intrinsic) muscles

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36
Q

what is the function of the extra-ocular eye muscles

A

move the eyeball within the orbit

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37
Q

what is the function of the intra-ocular eye muscles

A

change the shape of structures inside the eyeball

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38
Q

what is the name of the small radial muscle fibres that pass from edge of the pupil out across iris

A

dilator pupillae

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39
Q

what happens when fibres of dilator pupillae contract

A

medial edges of the iris are pulled outward increasing the size of the pupils

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40
Q

contracting dilator pupillae causes the pupil to ____ in size

A

grow

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41
Q

what is the innervation of dilator pupillae

A

sympathetic nervous system

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42
Q

the sympathetic nervous system innervates dilator pupillae to do what

A

pupil to dilate to give as much light to the retina as possible to detect danger and in low light to let enough light in to maintain retinal cell function

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43
Q

the iris also has circular fibres around the pupil called

A

sphincter pupillae

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44
Q

what happens when sphincter pupillae contracts

A

narrow the pupil, restricting amount of light getting into eye to protect the delicate retinal cells from high light intensities

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45
Q

what is the innervation of sphincter pupillae

A

parasympathetic control

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46
Q

the parasympathetic innervation to sphincter pupillae comes from what

A

carried by oculomotor nerve CN III

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47
Q

the sympathetic innervation of dilator pupillae comes from where

A

carried on blood vessels

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48
Q

how can you test oculomotor function

A

shine a light briefly in someones eye and if pupil constricts then oculomotor is working

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49
Q

what muscles act to change the shape of the lens for accomodation

A

ciliary muscles

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50
Q

what nerve supplies the ciliary muscle

A

oculomotor nerve (parasympathetic)

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51
Q

in the absence of nerve stimulation, the ciliary muscle is relaxed which causes the lens to do what

A

ciliary muscle relaxed
zonular fibres under tension
–> lens is stretched thin to refract light for distant vision

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52
Q

when the ciliary muscle receives nerve stimulation, it contracts causing the lens to do what

A

ciliary muscle contracts
zonular fibres relax
lens becomes more spherical to refract light for near vision

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53
Q

far vision requires a ____ lens and _____ ciliary muscle

A

thin lens
relaxed ciliary muscle

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54
Q

near vision requires a _____ and ____ ciliary muscle

A

fat
contracted

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55
Q

how many extra-ocular muscles are there

A

7

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56
Q

what are the extraocular muscles

A

levator palpebrae superioris
superior inferior medial and lateral rectus
superior and inferior oblique

57
Q

what are the attachments of levator palpebrae superioris

A

orbital roof to upper eyelid

58
Q

what are the attachments of the recti

A

annular ring to sclera (anterior to equator)

59
Q

what are the attachments of superior oblique

A

lesser wing of sphenoid to the sclera

60
Q

what are the attachments of inferior oblique

A

orbital floor to sclera (posterior to equator)

61
Q

what does levator palpebrae superioris do

A

raises upper eyelid

62
Q

does LPS move the eyeball

63
Q

where do the recti attach to the sclera in terms of the equator

A

4 cardinal points - north south east west - infront of the equator

64
Q

the oblique muscles attach infront/behind equator

65
Q

where does the optical axis run

A

through centre of eyes - line of gaze

66
Q

which side of the eyeball is more exposed

A

lateral side of eyeball more exposed as medial wall extends further out anteriorly from skull

67
Q

what determines the axis of the orbit

A

bony cavity

68
Q

what can eye muscles move eye in more than one direction

A

axes of orbit and optical axis different

69
Q

adduction of the eye is movement towards

70
Q

what is the action of levator palpebrae superioris

A

raise upper eyelid

71
Q

what is the action of superior rectus

A

elevation
adduction
intorsion

72
Q

what is the action of inferior rectus

A

depression
adduction
extorsion

73
Q

what is the action of medial rectus

74
Q

what is the action of lateral rectus

75
Q

what is the action of superior oblique

A

intorsion
depression
abduction

76
Q

what is the action of inferior oblique

A

extorsion
elevation
abduction

77
Q

what is the pneumonic for remembering eye muscle action

A

RADSIN

Recti ADDuct (except LR)
Superiors INtort

78
Q

what is intorsion

A

posterior part of the eye moves inwards

79
Q

what is the pneumonic for remembering eye muscle innervation

A

LR6 SO4 AO3

80
Q

what does LR6 SO4 AO3 mean

A

Lateral rectus - CN VI
Superior oblique - CN IV
all others - CN III

81
Q

the optic nerve leaves the orbit via

A

optic canal

82
Q

the optic nerve forms a chiasma where

A

over pituitary fossa

83
Q

what happens after the chiasma

A

optic tracts are sent towards the brain, e.g. to thalamus

84
Q

the optic radiations take information to be processed where

A

primary visual cortex

85
Q

where is the primary visual cortex

A

occipital lobe

86
Q

the other cranial nerves enter the orbit via

A

superior orbital fissure

87
Q

what supplies sensory innervation to the orbit

A

trigeminal nerve

88
Q

the trigeminal nerve carries fibres from what nerve to the lacrimal gland

A

facial nerve

89
Q

before the cranial nerves reach the superior orbital fissure they pass through what

A

cavernous dural venous sinus

90
Q

where is the cavernous dural venous sinus

A

lies around the body of the sphenoid bone and pituitary fossa

91
Q

what nerves pass along the walls close to the dura of the cavernous dural venous sinus

A

CN III, IV and V

92
Q

what nerve passes through the middle of the cavernous dural venous sinus

93
Q

CN VI passes through the middle of the cavernous dural venous sinus close to what

A

internal carotid artery

94
Q

what nerves pass through the annular ring

A

optic nerve CN II
oculomotor (inferior and superior division) CN III
abducent CN VI
nasociliary nerve

95
Q

what nerves pass outside the annular ring

A

lacrimal nerve (CN V1)
frontal nerve
trochlear nerve (CN IV)

96
Q

CN V1 is the ophthalmic division of the trigeminal nerve. it passes into what foramen

A

superior orbital fissure

97
Q

what branches of CN V1 lie superior to the extraocular muscles

A

frontal branches

98
Q

the frontal branch of CNV1 divides to give what

A

supraorbital and supratrochlear branches

99
Q

the supraorbital and supratrochlear nerves pass onto the face via what

A

supra-orbital notch

100
Q

what supplies sensory innervation to the skin of the forehead

A

supraorbital and supratrochlear branches

101
Q

what branch of CNV1 forms ethmoidal branches

A

nasociliary

102
Q

the _____ nerve acts as a carrier for parasympathetic secretomotor fibres from the facial nerve

103
Q

the frontal branch of CN V1 passes over the superior surface of what

104
Q

what nerve is the main supply to the extra-ocular muscles

A

oculomotor nerve CN III

105
Q

the superior division of the oculomotor nerve supplies motor innervation to what

106
Q

the inferior division of the oculomotor nerve supplies motor innervation to

107
Q

the oculomotor nerve also carries parasympathetic innervation to what

A

intrinsic muscles of the eye

108
Q

what is the name of the small piece of nerve tissue posterior to the eye which communicates with CN III and sends short ciliary nerves into the eyeball

A

ciliary ganglion

109
Q

does CN III or CN V1 lie deeper in the orbit

A

CN III lies deeper in the orbit

110
Q

the ciliary ganglion also receives sympathetic fibres carries by what

A

vessels of the orbit

111
Q

CN VI is associated with the surface of what muscle

112
Q

CN IV crosses the superior surface of

113
Q

blood supply to the orbit is from

A

ophthalmic artery

114
Q

the ophthalmic artery is a branch of what

A

internal carotid artery

115
Q

the ophthalmic artery gives what branches to the forehead and scalp

A

supraorbital, supratrochlear and zygomaticotemporal

116
Q

what branches does the ophthalmic artery give to the nose

A

dorsal nasal and ethmoid arteries

117
Q

the ophthalmic artery enters the orbit through

A

optic canal with optic nerve

118
Q

the ophthalmic veins of the orbit communicate with cavernous venous sinus through the …

119
Q

the ophthalmic veins of the orbit communicate with pterygoid venous plexus via

A

inferior orbital fissure

120
Q

the ophthalmic veins of the orbit communicates with what other vein

121
Q

describe the path of tears

A

tears released by lacrimal gland, they wash across the surface of the eye and are then gathered through lacrimal punctum into the lacrimal canaliculi and then into the lacrimal sac

122
Q

the lacrimal sac communicates with what part of the nose and how

A

lacrimal sac communicates with the inferior meatus of the nose via the nasolacrimal duct

123
Q

what is the innervation of the lacrimal duct

A

secretomotor fibres from the facial nerve (CN VII) carried in trigeminal (CN V1)

124
Q

what are the 2 parts of the lacrimal gland

A

orbital part
palpebral part

125
Q

how does the facial nerve supply secretomotor fibres to the submandibular and sublingual salivary glands

A

via the chorda tympani by joining lingual nerve (CN V3)

126
Q

parasympathetic fibres to the lacrimal gland also travel with the trigeminal nerve - what part?

A

CN V1 and V2

127
Q

why is the greater petrosal nerve called that

A

passes across the petrous part of the temporal bone and is the bigger nerve - lesser petrosal nerve is related to the pathway of CN IX to the parotid

128
Q

the greater petrosal nerve carries

A

parasympathetic secretomotor fibres

129
Q

the greater petrosal nerve joins with what to form what

A

deep petrosal nerve (sympathetic fibres from a plexus around the ICA) to form the nerve of the pterygoid canal

130
Q

the nerve of the pterygoid canal passes to what

A

pterygopalatine ganglion

131
Q

where is the pterygopalatine ganglion

A

at the fissure on the wall of the infratemporal fossa

132
Q

the nerve of the pterygoid canal joins with what

A

zygomatic branch of CNV2

133
Q

once the nerve of the pterygoid canal has joined with the zygomatic branch of CN V2, it then joins with to reach where

A

lacrimal nerve (CN V1) to finally reach the lacrimal gland

134
Q

the lesser petrosal is parasympathetic from

135
Q

the greater petrosal nerve is parasympathetic from

136
Q

deep petrosal is what kind of fibre

A

sympathetic

137
Q

nerve of the pterygoid canal has what kind of fibre

A

both sympathetic and parasympathetic

138
Q

how does the facial nerve supply tiny glands in the nose

A

small nerves passing from the pterygopalatine ganglion

Regional Anatomy (36 decks)

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