Ophthalmology anatomy Flashcards
1
Q
What bones contribute to the orbit?
A
orbital plate of frontal orbital plate of ethmoid zygomatic maxilla sphenoid lacramil
2
Q
what passes through the infraorbital foramen?
A
infraorbital NVB
3
Q
In what bone do the optic canal and superior orbital fissure lie?
A
sphenoid
4
Q
what shape is the orbit?
A
pyramidal, optic canal forms the apex which lies quite medial
5
Q
Name the 4 margins of the orbit
A
superior, inferior, medial and lateral. together form orbital ring
6
Q
What is the function of the orbital ring?
A
anything larger in diameter than the orbital ring can’t cause direct trauma to the eye
7
Q
What orbital bones are most likely to break?
A
floor and medial walls (maxillary, ethmoid, lacrimal)
This is a blowout fracture and orbital contents can become trapped and infraorbital NVB can be damaged (V2) resulting in general sensory deficit of the facial skin
8
Q
If the zygoma fractures, which way does it usually rotate?
A
medially, towards the eye
9
Q
which bone does the suspensory ligament of the eye attach to?
A
zygoma
10
Q
What muscles makes up the external layer of the eyelid? What are its two parts?
A
Orbicularis oculi
orbital and palpebral parts
11
Q
What nerve supplies the orbicularis oculi?
A
facial nerve CNVII
12
Q
What are the dense bands of half moon shaped connective tissue on upper and lower eyelids called?
A
superior and inferior tarsus
give shape to the eyelid
13
Q
What tendon attaches to the superior tarsus? What is its function?
A
tendon of levator palpebrae superioris
lifts the superior eyelid
14
Q
What name is given to the connective tissue around the orbit that is continuous with the periosteum? What is its function?
A
orbital septum
barrier against infection
15
Q
What is the function of the tarsal glands?
A
lipid secretion to prevent eyelids sticking together and overflow of lacrimal fluid
16
Q
Is the cornea vascularised?
A
no
17
Q
Where is the lacrimal fluid produced?
A
lacrimal gland
18
Q
Where does the lacrimal fluid pass into?
A
inferior lacrimal puncta
19
Q
Where does the conjunctiva cover?
A
the sclera, lower eyelid and upper eyelid, the conjunctival fornix is where the conjunctiva folds between the sclera and eyelid
20
Q
What cranial nerve supplies the lacrimal gland?
A
parasympathetics from facial nerve
21
Q
What is the average diameter of an eye?
A
25mm
22
Q
What are the 3 main layers of the eye?
A
fibrous outer layer vascular layer (uvea) inner layer (retina)
23
Q
How much refractive power comes from the cornea?
A
2/3
24
Q
What structures make up the uvea?
A
iris
cilliary body
choroid
25
Where does most nutrition and gas exchange take place in the eye?
Choroid
26
What segments make up the eye?
anterior and posterior
27
What chambers make up the anterior segment?
anterior and posterior
28
Where does the anterior chamber of the eye lie?
between iris and cornea
29
Where does the posterior chamber lie?
between the iris and suspensory ligaments
30
What liquid is contained in the chambers of the anterior segment?
aqueous humour
31
Where does the avascular cornea get its nutrition?
aqueous humour posteriorly and lacrimal fluid anteriorly
32
What fraction of the eye is contained in the posterior segment?
2/3 of the eye
33
What liquid is contained in the vitreous body of the posterior segment?
vitreous humour (more gel like)
34
What segment of the eye lies behind the lens?
Posterior segment
35
What part of the eye can be seen through a slit lamp?
anterior segment
36
Where do the cornea and sclera meet?
limbus/corneoscleral junction, seen as a greyish line around the iris
37
Where does the iridocorneal angle lie?
between the iris and cornea
38
Where is aqueous humour produced?
The cilliary body
39
What components make up the cilliary body?
smooth muscle and blood vessels
40
What name is given to the foldings of the cilliary body where the aqueous humour is produced?
cilliary processes
41
How does the aqueous humour pass from the posterior to anterior chamber to nourish the cornea?
through the pupil
42
Where does aqueous humour pass back into the venous system?
scleral venous sinus (Canal of Schlemm) at iridocorneal angle
43
Why is balance of secretion and reobstruction of aqueous humour important?
maintenance of intraorbital pressure
44
The ophthalmic arteriy is a branch of which branch of the common carotid?
internal carotid
45
Which artery passes inside the optic nerve?
Central artery of the retina. This is an end artery.
46
The cilliary arteries are branches of which artery?
Ophthalmic artery
47
Which is the only vein draining the retina?
central retinal vein
48
How does venous drainage leave the orbit?
Superior and inferior ophthalmic veins. These join before draining into the cavernous sinus. The orbit also drains anteriorly into the facial vein and towards the jugulars. Blood flow in this area is not always unidirectional.
49
What are the areas of the fundus called?
optic disc
macula
fovea
50
What name is given to the posterior section of the retina?
Fundus
51
Why is the optic disc known as the blind spot?
no photoreceptors here
52
What structure forms the optic disc?
Optic nerve
53
What structures enter the eyeball at the optic disc?
central artery and vein
54
What is special about the macula?
Acute vision, lots of cones. The central area of the macula is called the fovea, where the most acute vision occurs
55
What are the layers of the retina? (posterior to anterior)
Photoreceptors
Ganglion cells
Axons
Branches of retinal arteries and veins
56
What layer of the retina forms the optic nerve?
Axons
57
Which is more nasal, the macula or optic disc?
optic disc
58
Where does the left visual field hit the retinae?
nasal retina in the left eye, temporal retina of the right eye.
59
Which parts of the vision cross at the optic chiasma?
nasal retinal images
60
Where in the brain is the right visual field processed?
Left visual cortex?
61
What 7 extraoccular skeletal muscles control eyeball movement?
```
superior rectus
inferior rectus
medial rectus
lateral rectus
superior oblique
inferior oblique
levator palpebrae superioris
```
62
Where do the rectus muscles originate from?
common tendinous ring
63
What bone does the superior oblique originate from?
sphenoid bone
64
What is the name given to sling that the superior oblique passes through?
trochlea
65
describe somatic motor innervation of extraocular muscles
LR6 SO4 AO3
Lateral rectus= anducent (only job)
Superior oblique= trochlear (only job)
All others= oculomotor
66
What names are given to the axes of the eyeball?
vertical
transverse
anteroposterior
67
What is movement around the vertical axis?
adduct and abduct
68
What is movement around the transverse axis?
elevation and depression
69
What is movement around the anteroposterior axis?
intorsion and extorsion
70
How must the eyeball be aligned to test muscle function and nerve supply?
Aligned along plane of muscle
71
Describe clinical testing of the extraocular muscles and their primary movements
lateral rectus= abduct (ABDUCent)
superior rectus= elevation (when abducted)
inferior rectus= depression (when abducted)
medial rectus= adduction
inferior oblique= elevation (when adducted)
superior oblique= depression (when adducted
72
Describe the muscles needed for pure elevation of the eye
superior rectus and inferior oblique, both want to elevate and cancel each other out in terms of rotation (superior=medial, inferior=lateral). Here they work as both synergists and antagonists
73
What cranial nerve gives sensation to the face?
Trigeminal
74
What branch of the trigeminal nerve gives sensation to the upper eyelid, cornea, conjunctiva and the skin of the root, bridge and tip on the nose?
Ophthalmic branch (CNV1)
75
What branch of the trigeminal nerve supplies the skin of the lower eyelid, skin of the maxilla, skin of the ala, skin and mucosa of the upper lip?
Maxillary nerve (CNV2)
76
Which branch of the trigeminal nerve gives off the infraorbital nerve?
Maxillary nerve (CNV2)
77
What nerves are involved in the blink reflex?
sensory afferent limb-Action potentials from the cornea via ophthalmic nerve to the trigeminal ganglion, then along trigeminal nerve to the pons.
Central CNS connections between trigeminal and facial nerves.
motor efferent limb- action potentials conducted via the facial nerve to the palpebral part of the orbicularis oculi
78
Why is the blink reflex important?
Prevents dessication of the eye, nourishes the cornea and helps wash away any foreign bodies
79
From what spinal levels do the sympathetic fibres exit?
T1-L2 and travel to the sympathetic trunks. They then pass into all spinal nerves (anterior and posterior rami)
80
Describe the cervical part of the sympathetic axis.
Axons exit at T1 then pass into the sympathetic chain and head up to the three cervical ganglia (superior, middle and inferior). They synapse at superior cervical ganglia. Post-synaptic axons pass onto the surfaces of the external and internal carotid arteries and become internal and external carotid nerves. This is a periarterial sympathetic plexus. The nerves follow the arteries in order to reach the organs. Sympathetic axons follow the internal carotid up the the ophthalmic artery and then into the eye.
81
What cranial nerves does parasympathetic innervation originate from?
CN III, VII, IX and X and sacral spinal nerves
82
What name is given to the parasympathetic ganglion in the head that supplies the eye?
ciliary ganglion in the orbit
83
What cranial nerve supplies presynaptic axons to the ciliary ganglion?
Oculomotor
84
What types of nerves pass through they ciliary ganglion?
sensory somatic
sympathetic
parasympathetics
85
What types of nerves pass through they ciliary ganglion?
sensory somatic (CNV1)
sympathetic
parasympathetics
86
What nerve, involved in the blink reflex, follows the path of the ophthalmic artery around the eyeball?
long ciliary nerve
87
Describe vestibulo-ocular reflex.
turns eyes in the opposite direction to head movement to stabilise gaze. CNS connections betweem CN VIII and CN III, IV and VI
88
Describe the oculocardiac reflex.
reflex bradycardia in response to tension on the extraocular muscles or pressure on the eye. Connections between CN V1 and CN X
89
Describe the action of sympathetic stimulation on the eye.
opens eyes wider
gets more light into the eyes
focus on far objects
90
Describe the action of parasympathetic stimulation on the eye.
allows orbicularis oculi to work
gets less light into eyes
focus on near objects
reflex lacrimation
91
what 2 sets of muscles surround the pupil?
dilator pupillae fibres
92
what 2 sets of muscles surround the pupil?
dilator pupillae fibres
| sphincter pupillae fibres
93
What name is given to a non-physiologically constricted pupil? When may it be seen?
miotic
Horner's syndrome
94
What muscle is at fault in fixed pin point and fixed dilated pupils?
sphincter pupillae fibres
95
What nerve give parasympathetic control to the sphincter pupillae fibres?
Oculomotor nerve
96
What is the affernet limb in pupillary light reflex?
Optic nerve
97
What is the efferent nerve of the pupillary light reflex?
oculomotor nerve
98
What happens in the other when when you stimulate one eye by shining light directly into it?
constriction of the pupil
99
How many neurones are involved in the pupillary light reflex?
4 neurone chain
100
Describe the 4 neurone chain in the pupillary light reflex.
1st neurones=retinal ganglion cells pass via the ipsilateral optic nerve to dessucate in the optic chiasm. They synapse in the pretectal nucleus in the midbrain.
FINISH SLIDE 21
101
Suspensory ligaments attach which structure to the lens?
Ciliary body
102
When is the ciliary muscle relaxed? What shape is the lens?
far vision
| Lens becomes longer and flatter
103
When is the ciliary muscle contracted? What shape is the lens?
Near vision
| lens becomes shorter and fatter
104
What 3 components are clinically assessed in the accomodation reflex? (bringing finger towards tip of nose)
Bilateral pupillary constriction
Bilateral convergence of both eyes towards the midline
Bilateral relaxation of the lens
105
What 3 components are clinically assessed in the accommodation reflex? (bringing finger towards tip of nose)
Bilateral pupillary constriction
Bilateral convergence of both eyes towards the midline
Bilateral relaxation of the lens
106
What nerve is tested in the accommodation reflex? (bringing finger tip towards nose)
Oculomotor
107
What is the afferent limb in lacrimation reflex?
Ophthalmic nerve
108
What is the efferent limb in lacrimation reflex?
Parasympathetic axons from facial nerve
109
Where does the common tendinous ring attach to the sphenoid bone?
around the orbital opening of the optic canal
110
What is the Monro-Kellie hypothesis?
You cannot change the pressure within the intracranial cavity without altering the brain size, blood volume, CSF as intracranial volume is constant
111
What name is given to the space between the arachnoid and pia?
Subarachnoid space
112
What are the layers of meninges covering the optic nerve?
Dura
Arachnoid
Pia
113
Which layer of the meninges has sensation? What nerve supplies this?
Dura
| Trigeminal
114
Where does the CSF drain into the venous system?
Arachnoid granulations occuring at the superior sagital sinus
115
At what spinal level would you take a lumbar puncture?
L3/4 or L4/6
116
At what level does the spinal cord end?
L2
117
At what level does the CSF end?
S2
118
Where is the CSF produced?
Choroid plexus of the ventricles
119
Through which 4 foramina can the CSF exit the 4th ventricle from?
2x Lateral foramina
Medial foramina
Spinal canal
120
What direction can the eye not move in in trochlear nerve palsy?
Inferomedially
