The orbit Flashcards
1
Q
what bone forms the roof of the orbit
A
frontal bone
2
Q
the frontal bone forms what parts of the orbit
A
roof, parts of medial and parts of lateral walls
3
Q
the frontal bone has a notch for what
A
supraorbital nerve and artery
4
Q
what deflects blows to the face away from the eyes
A
supraorbital ridge
5
Q
what bone forms part of the lateral wall of the orbit (not frontal)
A
zygoma
6
Q
what bone forms a large part of the floor of the orbit
A
maxilla
7
Q
what bone forms the infraorbital foramen
A
maxilla
8
Q
what passes through the infraorbital foramen
A
infraorbital branch of CNV2 exits skull via infraorbital foramen
9
Q
what bone forms the naso-lacrimal duct
A
lacrimal
10
Q
what is the purpose of the naso-lacrimal duct
A
carries excess lacrimal fluid (tears) into the nasal cavity
11
Q
what bone forms part of the medial wall of the orbit but also contributes to the nasal cavities
A
ethmoid bone
12
Q
what is the butterfly shaped bone in the skull called
A
sphenoid bone
13
Q
what foramina does the sphenoid bone form
A
optic canal
superior orbital fissure
contributes to the inferior orbital fissure
14
Q
what passes through the inferior orbital fissure
A
ophthalmic veins
15
Q
what nerves pass through the superior orbital fissure
A
CN III
CN IV
CN V
CN VI
16
Q
there is a tiny contribution from what in wall of inferior orbital fissure
A
palatine
17
Q
what is contained in the orbit
A
eyeball fat and connective tissue extra-ocular muscles nerves blood vessels
18
Q
the orbital contents are protected anteriorly by what
A
orbital septum composed of strong connective tissue
19
Q
the corners of the eyelid are supported by what
A
medial and lateral palpebral ligaments
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
21
Q
what is the function of the check ligaments
A
restrict the movements of the extra-ocular muscles - restrict medial and lateral recti
22
Q
what is the function of the suspensory ligament of the eye
A
supports the position of the eyeball within the orbit
23
Q
what forms the outer coat of the eyeball
A
cornea and sclera - fibrous layers
24
Q
what is the middle layer of the eyeball
A
vascular layer - iris, ciliary body and choroid
25
what is the inner layer of the eye
retina
26
what is the blind spot
area where the optic nerve leaves the eye so it is void of rods and cones
27
what is the area of the retina that is rich in both rods and cones
macula lutea (fovea)
28
where is the anterior chamber of the eye
between the lens and the cornea
29
what is in the anterior chamber of the eye
aqueous humor - thin fluid
30
what makes aqueous humor
cells of the ciliary body
31
how is aqueous humour recycled
recycled back into veins at the junction of the cornea and sclera
(corneo-scleral junction - canal of Schlemm)
32
what fills the posterior chamber of the eye
vitreous humour (gel)
33
what is the function of the vitreous humor
supports the retina by gently pressing it against the choroid below
34
the choroid has what
blood vessels that supply the retina
35
what are the 2 types of muscles associated with the eyeball
extra-ocular (Extrinsic) muscles
| intra-ocular (intrinsic) muscles
36
what is the function of the extra-ocular eye muscles
move the eyeball within the orbit
37
what is the function of the intra-ocular eye muscles
change the shape of structures inside the eyeball
38
what is the name of the small radial muscle fibres that pass from edge of the pupil out across iris
dilator pupillae
39
what happens when fibres of dilator pupillae contract
medial edges of the iris are pulled outward increasing the size of the pupils
40
contracting dilator pupillae causes the pupil to ____ in size
grow
41
what is the innervation of dilator pupillae
sympathetic nervous system
42
the sympathetic nervous system innervates dilator pupillae to do what
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
43
the iris also has circular fibres around the pupil called
sphincter pupillae
44
what happens when sphincter pupillae contracts
narrow the pupil, restricting amount of light getting into eye to protect the delicate retinal cells from high light intensities
45
what is the innervation of sphincter pupillae
parasympathetic control
46
the parasympathetic innervation to sphincter pupillae comes from what
carried by oculomotor nerve CN III
47
the sympathetic innervation of dilator pupillae comes from where
carried on blood vessels
48
how can you test oculomotor function
shine a light briefly in someones eye and if pupil constricts then oculomotor is working
49
what muscles act to change the shape of the lens for accomodation
ciliary muscles
50
what nerve supplies the ciliary muscle
oculomotor nerve (parasympathetic)
51
in the absence of nerve stimulation, the ciliary muscle is relaxed which causes the lens to do what
ciliary muscle relaxed
zonular fibres under tension
--> lens is stretched thin to refract light for distant vision
52
when the ciliary muscle receives nerve stimulation, it contracts causing the lens to do what
ciliary muscle contracts
zonular fibres relax
lens becomes more spherical to refract light for near vision
53
far vision requires a ____ lens and _____ ciliary muscle
thin lens
| relaxed ciliary muscle
54
near vision requires a _____ and ____ ciliary muscle
fat
| contracted
55
how many extra-ocular muscles are there
7
56
what are the extraocular muscles
levator palpebrae superioris
superior inferior medial and lateral rectus
superior and inferior oblique
57
what are the attachments of levator palpebrae superioris
orbital roof to upper eyelid
58
what are the attachments of the recti
annular ring to sclera (anterior to equator)
59
what are the attachments of superior oblique
lesser wing of sphenoid to the sclera
60
what are the attachments of inferior oblique
orbital floor to sclera (posterior to equator)
61
what does levator palpebrae superioris do
raises upper eyelid
62
does LPS move the eyeball
no
63
where do the recti attach to the sclera in terms of the equator
4 cardinal points - north south east west - infront of the equator
64
the oblique muscles attach infront/behind equator
behind
65
where does the optical axis run
through centre of eyes - line of gaze
66
which side of the eyeball is more exposed
lateral side of eyeball more exposed as medial wall extends further out anteriorly from skull
67
what determines the axis of the orbit
bony cavity
68
what can eye muscles move eye in more than one direction
axes of orbit and optical axis different
69
adduction of the eye is movement towards
the nost
70
what is the action of levator palpebrae superioris
raise upper eyelid
71
what is the action of superior rectus
elevation
adduction
intorsion
72
what is the action of inferior rectus
depression
adduction
extorsion
73
what is the action of medial rectus
adduction
74
what is the action of lateral rectus
abduction
75
what is the action of superior oblique
intorsion
depression
abduction
76
what is the action of inferior oblique
extorsion
elevation
abduction
77
what is the pneumonic for remembering eye muscle action
RADSIN
```
Recti ADDuct (except LR)
Superiors INtort
```
78
what is intorsion
posterior part of the eye moves inwards
79
what is the pneumonic for remembering eye muscle innervation
LR6 SO4 AO3
80
what does LR6 SO4 AO3 mean
Lateral rectus - CN VI
Superior oblique - CN IV
all others - CN III
81
the optic nerve leaves the orbit via
optic canal
82
the optic nerve forms a chiasma where
over pituitary fossa
83
what happens after the chiasma
optic tracts are sent towards the brain, e.g. to thalamus
84
the optic radiations take information to be processed where
primary visual cortex
85
where is the primary visual cortex
occipital lobe
86
the other cranial nerves enter the orbit via
superior orbital fissure
87
what supplies sensory innervation to the orbit
trigeminal nerve
88
the trigeminal nerve carries fibres from what nerve to the lacrimal gland
facial nerve
89
before the cranial nerves reach the superior orbital fissure they pass through what
cavernous dural venous sinus
90
where is the cavernous dural venous sinus
lies around the body of the sphenoid bone and pituitary fossa
91
what nerves pass along the walls close to the dura of the cavernous dural venous sinus
CN III, IV and V
92
what nerve passes through the middle of the cavernous dural venous sinus
CN VI
93
CN VI passes through the middle of the cavernous dural venous sinus close to what
internal carotid artery
94
what nerves pass through the annular ring
optic nerve CN II
oculomotor (inferior and superior division) CN III
abducent CN VI
nasociliary nerve
95
what nerves pass outside the annular ring
```
lacrimal nerve (CN V1)
frontal nerve
trochlear nerve (CN IV)
```
96
CN V1 is the ophthalmic division of the trigeminal nerve. it passes into what foramen
superior orbital fissure
97
what branches of CN V1 lie superior to the extraocular muscles
frontal branches
98
the frontal branch of CNV1 divides to give what
supraorbital and supratrochlear branches
99
the supraorbital and supratrochlear nerves pass onto the face via what
supra-orbital notch
100
what supplies sensory innervation to the skin of the forehead
supraorbital and supratrochlear branches
101
what branch of CNV1 forms ethmoidal branches
nasociliary
102
the _____ nerve acts as a carrier for parasympathetic secretomotor fibres from the facial nerve
lacrimal
103
the frontal branch of CN V1 passes over the superior surface of what
LPS
104
what nerve is the main supply to the extra-ocular muscles
oculomotor nerve CN III
105
the superior division of the oculomotor nerve supplies motor innervation to what
LPS
| SR
106
the inferior division of the oculomotor nerve supplies motor innervation to
MR
IR
IO
107
the oculomotor nerve also carries parasympathetic innervation to what
intrinsic muscles of the eye
108
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
ciliary ganglion
109
does CN III or CN V1 lie deeper in the orbit
CN III lies deeper in the orbit
110
the ciliary ganglion also receives sympathetic fibres carries by what
vessels of the orbit
111
CN VI is associated with the surface of what muscle
LR
112
CN IV crosses the superior surface of
SO
113
blood supply to the orbit is from
ophthalmic artery
114
the ophthalmic artery is a branch of what
internal carotid artery
115
the ophthalmic artery gives what branches to the forehead and scalp
supraorbital, supratrochlear and zygomaticotemporal
116
what branches does the ophthalmic artery give to the nose
dorsal nasal and ethmoid arteries
117
the ophthalmic artery enters the orbit through
optic canal with optic nerve
118
the ophthalmic veins of the orbit communicate with cavernous venous sinus through the ...
SOF
119
the ophthalmic veins of the orbit communicate with pterygoid venous plexus via
inferior orbital fissure
120
the ophthalmic veins of the orbit communicates with what other vein
facial
121
describe the path of tears
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
the lacrimal sac communicates with what part of the nose and how
lacrimal sac communicates with the inferior meatus of the nose via the nasolacrimal duct
123
what is the innervation of the lacrimal duct
secretomotor fibres from the facial nerve (CN VII) carried in trigeminal (CN V1)
124
what are the 2 parts of the lacrimal gland
orbital part
| palpebral part
125
how does the facial nerve supply secretomotor fibres to the submandibular and sublingual salivary glands
via the chorda tympani by joining lingual nerve (CN V3)
126
parasympathetic fibres to the lacrimal gland also travel with the trigeminal nerve - what part?
CN V1 and V2
127
why is the greater petrosal nerve called that
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
the greater petrosal nerve carries
parasympathetic secretomotor fibres
129
the greater petrosal nerve joins with what to form what
deep petrosal nerve (sympathetic fibres from a plexus around the ICA) to form the nerve of the pterygoid canal
130
the nerve of the pterygoid canal passes to what
pterygopalatine ganglion
131
where is the pterygopalatine ganglion
at the fissure on the wall of the infratemporal fossa
132
the nerve of the pterygoid canal joins with what
zygomatic branch of CNV2
133
once the nerve of the pterygoid canal has joined with the zygomatic branch of CN V2, it then joins with to reach where
lacrimal nerve (CN V1) to finally reach the lacrimal gland
134
the lesser petrosal is parasympathetic from
CN IX
135
the greater petrosal nerve is parasympathetic from
CN VII
136
deep petrosal is what kind of fibre
sympathetic
137
nerve of the pterygoid canal has what kind of fibre
both sympathetic and parasympathetic
138
how does the facial nerve supply tiny glands in the nose
small nerves passing from the pterygopalatine ganglion
