Lectures 17 & 18 Eye & Orbit Flashcards
(105 cards)
1
Q
List bones of orbit?
A
- Frontal
- Zygomatic
- Maxillary
- Lacrimal
- Sphenoid - optic canal passes through sphenoid
- Ethmoid (orbital plate)
- Palatine bone (orbital process - a small contribution medial to inferior orbital fissure)
2
Q
Superior orbital fissure is crossed by?
A
Oculomotor, branches of V1 (lacrimal, frontal, nasociliary), trochlear, abducens nerve
3
Q
Openings of the orbit
A
- superior orbital fissure
- inferior orbital fissure
- infraorbital groove & foramen
- optic foramen
- lacrimal canal
- anterior & posterior ethmoid foramina
- zygomatico-orbital foramin
- supraorbital foramen
- trochleal fovea or spine
4
Q
Infraorbital groove & foramen are crossed by?
A
Maxillary/infraorbital nerve (CNV/2)
5
Q
Optic foramen is for which nerve?
A
Optic nerve (CN2)
6
Q
Trochleal fovea or spine is located where and for what?
A
Halfway between supraorbital notch/foramen & frontolacrimal suture, for superior oblique muscle
7
Q
Where does levator palpebrae superioris arise?
A
Arises lesser wing sphenoid, above superior rectus & optic canal
8
Q
Function of levator palpebrae superioris
A
Raises upper eyelid
9
Q
Frontal nerve is inferior to levator palpebrae superioris
A
False, it is superior
10
Q
Rectus muscles insert where?
A
Recti insert into sclera about 6mm behind cornea & anterior to insertion of obliques
11
Q
Superior, inferior, and medial recti arise?
A
Arises tendinous ring around optic nerve
12
Q
______ has two heads - from lateral part of tendinous ring and from adjoining margin of ___________ ( _____ )
A
Lateral rectus, superior orbital fissure (sphenoid)
13
Q
Oblique extrinsic muscles insert?
A
Obliques insert further back, behind equator of eyeball
14
Q
__________ arises from body of sphenoid superomedial to optic canal.
A
Superior oblique muscle
15
Q
___________ passes forwards along medial wall of orbit to tendinous band (called a trochlea) attached to trochleal fovea
A
Superior oblique muscle tendon
16
Q
Where does superior oblique tendon insert?
A
Inserts into sclera between superior and lateral rectus
17
Q
___________ arises orbital surface of maxilla lateral to nasolacrimal groove.
A
Inferior oblique
18
Q
Where does inferior oblique muscle pass ?
A
Passes between inferior rectus and orbital floor and then between orbit and rectus lateralis
19
Q
Inferior oblique muscle inserts?
A
Behind equator between rectos inferior and rectus lateralis
20
Q
Medial and lateral recti rotate eye around horizontal axis
A
False, it rotates around vertical axis
21
Q
Eye movement of superior and inferior rectus?
A
Elevation and depression
22
Q
Eye movement of superior obliques
A
Down and out
23
Q
Eye movement of inferior oblique
A
Turns eye up and out
24
Q
List the structures of palpebral area
A
- tarsal plate
- tendon of levator palpebrae superioris
- lateral & medial palpebral ligaments
- orbital septum
- sebaceous tarsal glands
25
What is 'orbital septum'?
Fascial sheet attached to periosteum of orbital rim & levator tendon
26
What are eyelids lined with?
Conjunctiva which is continuous with cornea
27
What does conjunctiva contain?
Goblet cells
28
Another name of sebaceous tarsal glands?
Meibom's glands
29
Where do sebaceous tarsal glands empty into?
Free margin of the eyelid. The oily secretion spreads out over the tear film & contributes to its stability
30
Location of lacrimal glands
Mostly in superolateral orbit, some in eyelid lateral to tarsal plate between conjunctiva & palpebral fascia.
31
Composition of tears?
Mix of serous (from lacrimal glands), mucus (from conjunctiva goblet cells) and sebaceous (from sebaceous tarsal glands)
32
Where do tears drain?
Tears drain into medial corner of the eye & from there into the nasolarcimal duct via lacrimal canaliculi (one per eyelid, above & below plica semilunaris) & lacrimal sac
33
What is the canal of schlemm?
- Scleral venous sinus (trabecular meshwork)
| - drainage of aqueous humour
34
What is the ora serrata?
- Junction of sensory and non-sensory retina
35
List the 3 layers of the wall of the eyeball?
- Sclera/cornea
- Uvea
- Retina
36
What is the cornea/sclera?
Fibrous outer coat
37
What is the uvea?
Vascular intermediate coat, includes choroid (underlies sensory retina) & anterior parts of ciliary body & iris
38
Retina has two which parts?
- Sensory retina
| - non-sensory retina
39
Describe sensory retina
10 cell layers thick - photoreceptors (rods & cones) & other neurons
40
Describe non-sensory retina
2 cell layers thick - which forms the posterior parts of ciliary body & iris
41
Hollow centre of eyeball consists of anterior, posterior & vitreous chambers containing humours
True
42
Location of anterior chamber?
It's between cornea & iris
43
Location of posterior chamber?
Behind iris and in front of lens
44
Location of vitreous chamber
Behind lens
45
Refractive media of eye includes?
- Conrea,
- Aqueous humour
- Lens
- Vitreous humour
46
What is the main refractive apparatus (focusing light onto retina)?
Cornea
47
Function of iris?
Variable aperture to control amount of light onto retina
48
Structure of iris?
Anterior part - uvea
| Posterior part - non sensory retina (just 2 cells thick)
49
Which muscle contracts and expands iris?
Circular muscle around pupil contracts (sphincter) & expand (dilate)
50
Innervation of iris?
- Parasympathetic fibres of oculomotor origin - dilation via radial muscle extending outwards from pupil
- Sympathetic innervation
51
Two functions of ciliary body?
- Production of aqueous humour
| - Accommodation for far and near vision
52
Structure of ciliary body?
- Anterior part: uvea
| - Posterior part: non-sensory retina (2 cell layers thick)
53
Function of lens?
Accommodation for near & far vision
54
Describe structure of lens
- Flexible cellular structure
| - Attached to ciliary body by zonule fibres
55
What is 'accommodation'?
Adjusting focus to be able to see near or far objects. Lens, ciliary body and zonule fibres are involved.
56
How are lens attached to ciliary body?
Via zonule fibres (complex structure including collagen)
57
When ________ (circular muscle) of ciliary body contracts (parasympathetic control) the diameter of the ciliary body is reduced & there is less tension on zonule fibres
Sphincter, this in turn means less 'pull' on lens which rounds out/becomes less fat
58
A rounder lens accommodates for?
Near vision
59
How many layers of sensory retina?
10 layers
60
How to recognise sensory retina?
Thickened region on inner surface of posterior & lateral eyeball.
61
Junction of sensory retina and non-sensory retina of ciliary body?
Ora serrata
62
From outer to inner surface of sensory retina:
Pigment epithelium -> photoreceptors -> inner surface of retina
63
How thick is pigment epithelium? Location and function?
1 cell thick, and lies outside rods and cones and phagocytoses worn out components of rods and cones
64
What do photoreceptors consist of and location?
Rods and cones, and are in outer retina adjacent to posterior pigment epithelium
65
In sensory retina, the visual signal first goes inwards through a chain of neurons then over the inner surface of retina to the optic nerve.
True
66
What is the 'blind spot'?
Special areas of the sensory retina include the optic disc at the site of the entry of the optic nerve (lacks photoreceptors)
67
What is the 'macula/fovea'?
Region adjacent to the optic disc where the elements of the retina except the cones are reduced - region of greatest visual acuity.
68
There is an actual attachment between pigment epithelium & outer sensory retina which can become separated from the pigment epitheliulm (detached retina)
False, there is no actual attachment
69
Which type of humours fill which chambers in the eye?
- Aqueous humour fills anterior and posterior chambers.
| - Vitreous humour fills vitreous chamber
70
Describe properties of aqueous humour
- Fluid similar to blood plasma, constantly renewed
- Aqueous humour is produced in folds of ciliary body
- Transported into posterior chamber
- Passes through pupil and into anterior chamber
71
Where does aqueous humour drain?
Drains from eye into scleral venous sinus (canal of Schlemm) & from there into OPTHALMIC VEINS
72
Describe vitreous humour
- Fluid connective tissue, not constantly renewed
| - Stored in vitreous chamber, behind lens
73
The nerves oculomotor, ophthalmic, trochlear, abducent nerves pass through ______ along with internal carotid ______________.
Cavernous sinus, carrying carotid sympathetic plexus
74
Sympathetic fibres are transferred in the _______ from carotid plexus to other nerves crossing _______.
Cavernous sinus, cavernous sinus
75
List the nerves supplying extrinsic eye muscles
- Oculomotor
- Trochlea
- Abducent
76
What does oculomotor nerve supply?
Supplies all but two muscles of orbit
- superior division supplies superior rectus & levator palpebrae superioris
- inferior division supplies inferior & medial rectus, inferior oblique
77
What does trochlea nerve supply?
Superior oblique nerve
78
What does abducens nerve supply?
Lateral rectus
79
What does ophthalmic nerve supply?
Supplies structures within or near eyeball apart from intrinsic muscles & retina.
80
List branches of ophthalmic nerve
- Lacrimal
- Frontal
- Nasociliary
81
How do branches of ophthalmic nerve arise?
Arise as sensory nerves but lacrimal & nasociliary carry hitchikers
82
Lacrimal supplies lacrimal gland and skin
True
83
Parasympathetic fibres from the greater petrosal branch of facial nerve via pterygopalatine ganglion & maxillary nerve also supply lacrimal gland
True
84
Branches of frontal nerve?
Supratrochlear nerve, supraorbital nerve
85
Where does supraorbital nerve pass over?
Supraorbital nerve passes over superior surface of levator palpebrae superioris.
86
List branches of nasociliary branch of ophthalmic nerve
- sensory ganglion branches
- long ciliary nerves
- posterior ethmoidal
- infratrochlear nerve
- anterior ethmoid nerve
87
Sensory ganglion branches of nasociliary goes to parasympathetic ciliary ganglion
True
88
___________ (sympathetic & sensory) via sclera to dilator muscles of pupil & cornea
Long ciliary nerves
89
Posterior ethmoidal branches of nasociliary goes via posterior ethmoid foramina
True
90
What are the two terminal branches of nasociliary?
- Infratrochlear nerve
| - Anterior ethmoid nerve
91
Describe infratrochlear nerve
A cutaneous nerve which emerges just medial to inner corner of eye
92
Describe anterior ethmoid nerve
Goes to anterior ethmoid sinuses, nasal cavity and has a cutaneous branch the external nasal nerve
93
_________ is about 1cm in front of the tendinous ring & between lateral rectus & optic nerve
Ciliary ganglion
94
Describe the roots of the ciliary ganglion
- Sensory fibres from nasociliary nerve via the short ganglion branches
- Preganglionic parasympathetic fibres from the (inferior division) of the oculomotor
- Sympathetic fibres from the ophthalmic artery plexus
95
What do ciliary ganglion branches supply and how many?
6-10 short ciliary nerves via sclera supply iris & ciliary body & to the cornea.
96
Parasympathetic innervation of iris and ciliary body are required to:
- contract sphincters of pupil & ciliary body
- contraction of ciliary muscle -> decrease tension on zonule fibres connecting ciliary body & lens result in a decrease in the diameter of the ciliary body. This results in lens becoming more round and gives accommodation for near vision - focusing light onto retina.
97
Sympathetic innervation is required to:
- dilate pupil
| - vasomotor (constriction) to blood vessels
98
Describe the pupillary reflex
Light into one eye then both pupils should contract as retina sends fibres into optic tracts of both sides. If the parasympathetic supply to the sphincter of iris (oculomotor nerve) is compromised then sphincter is slow ("2 in, 3 out")
99
Describe the corneal reflex
Afferent via ophthalmic nerve, efferent via facial to orbicularis oculi ("5 in, 7 out")
100
________ is a branch of the internal carotid - enters optic canal with optic nerve.
Ophthalmic artery
101
Ophthalmic artery supplies?
Both orbit & eyeball.
102
Orbital branches of ophthalmic artery supply?
- Orbital structures - lacrimal gland, sclera, choroid, iris & ciliary body
- Supraorbital & supratrochlear branches to eyelids & skin of forehead
- Branches to ethmoid, frontal & sphenoid sinuses
- Some of the meninges
- Retinal branch
103
Define retinal branch and its supply
Central artery of retina (arises below optic nerve, enters retina at optic disc, divides into branches).
104
Central artery is the only supply to retina, no anastomosis between branches.
True
105
Describe the venous drainage of the retina
- Retinal veins - converge on optic disc & enter optic nerve as central vein of retina. These drain into superior ophthalmic vein -> cavernous sinus
- Inferior ophthalmic vein drains orbit -> cavernous sinus. Thus both ophthalmic veins have linkages with pterygoid venous plexus.
