Anatomy Flashcards
(93 cards)
1
Q
what is the iris?
A
thin diaphragm
2
Q
what does the iris control?
A
size of the pupil which is an opening in the iris
3
Q
what is sclera covered by?
A
conjunctiva
4
Q
what is the iris covered by?
A
cornea
5
Q
what are the three layers of the eye?
A
- fibrous (outer layer)
- uvea (vascular/middle layer)
- retina (photosensitive/ inner layer)
6
Q
what does the fibrous layer consist of?
A
sclera
cornea
7
Q
what does the uvea consist of?
A
iris
ciliary body
choroid
8
Q
what are the two segments of the eye?
A
- anterior segment
2. posterior segment
9
Q
where is the anterior segment?
A
in front of the lens
10
Q
what is the anterior segment split into?
A
anterior chamber
posterior chamber
11
Q
where is in the anterior chamber?
A
between cornea and iris
12
Q
where is the posterior chamber?
A
between iris and suspensory ligaments
13
Q
where is the posterior segment?
A
behind the lens
14
Q
what does the posterior segment contain?
A
vitreous body to secrete vitreous humour
collagen can clump together to form floaters
15
Q
what secretes aqueous?
A
ciliary body has ciliary processes that secrete aqueous
16
Q
where is aqueous reabsorbed?
A
Canal of Schlemm at the iridocorneal angle
17
Q
role of aqueous
A
nourishes avascular structures
18
Q
describe the arterial supply to the eye
A
ICA gives off the ophthalmic artery which branches into ciliary arteries and central artery of the retina
19
Q
how does the ICA get into the cranial cavity?
A
carotid canal
20
Q
what does the ophthalmic artery pass through?
A
optic canal
21
Q
what is the fundus?
A
area on the retina where light is focused
22
Q
what does the fundus contain?
A
optic disc
macula
fovea
23
Q
what is the optic disc?
A
CNII formation
point of entry/exit for blood vessels and axons
24
Q
where is the fovea found?
A
centre of the macula
25
where are objects in the right visual field processed in the brain?
left visual cortex
26
what are the 6 extraocular muscles?
```
lateral rectus
superior rectus
inferior rectus
medial rectus
inferior oblique
superior oblique
```
27
role of LR
abduct the eye
| brings into plane of SR and IR
28
role of SR
when in abduction, it elevates
29
role of IR
when in abduction, it depresses
30
role of MR
adducts
| brings into plane of SO and IO
31
role of IO
when in adduction, it elevates
32
role of SO
when in adduction, it depresses
33
innervation of the extraocular muscles
LR6, SO4, AO3
34
role of levator papillae superioris
elevates the eyelid
35
innervation of levator papillae superioris
CNIII
36
what does the SO run through before inserting onto sclera?
trochlea
37
where do all the rectus muscles originate from?
common tendinous ring (annulus ring)
38
where does SO originate from?
sphenoid
39
where does IO originate from?
maxilla
40
where do all the extraocular muscles insert?
sclera
41
what supplies somatosensory innervation to the face?
CNV
42
what does CNV1 (ophthalmic division) provide sensation to?
upper eyelid
cornea
conjunctiva
43
what branch of CNV1 supplies the face and how does it get there?
supraorbital branch passes through the supraorbital foramen
+ nasal skin branches
44
what does CNV2 (maxillary branch) provide sensation to?
skin of lower eyelid
| skin over maxilla
45
what branch of CNV2 supplies the face and how does it get there?
infraorbital nerve via the infraorbital foramen
46
what does CNV3 (mandibular branch) provide sensation to?
skin over mandible
| TMJ, except angle of the mandible
47
what is the corneal reflex?
blinking
48
describe the pathway of the corneal reflex?
AP conducted from cornea via CNV1 to trigeminal ganglia along CNV to pons to CNVII to orbicularis oculi
49
sympathetic effect on the eye
opens eyes wider
gets more light into the eyes
focuses on far objects
50
parasympathetic effect on the eye
less light (protection/ when asleep)
focus on near objects
reflex lacrimation
51
what is the vestibulo-ocular reflex?
eyes turn in opposite direction to head movement
| stabilises gaze
52
cranial nerve connections in vestibulo-ocular reflex
CNVII and CNIII, IV and VI
53
what is the oculocardiac reflex?
reflex bradycardia in response to tension in extraocular muscles/ pressure on eye
54
what division of the nervous system is involved in pupillary constriction?
parasympathetic innervation along CNIII to sphincter pupillae
55
what is pinpoint pupils an issue with?
pontine
56
what division of the nervous system causes pupillary dilation?
sympathetic innervation to dilator pupillae
57
what is the pupillary light reflex?
response to shining light into the eye causes pupillary constriction of both eyes
58
what nerve connections are involved in the pupillary light reflex?
ipsilateral CNII
midbrain (PTN > EWN > ciliary ganglion > ciliary nerve)
bilateral CNIII (direct and consensual response)
59
what is the lens accommodation reflex?
changes in the lens shape to look at close and distant objects
60
lens accommodation reflex in far vision
ciliary muscle relaxes causing ligaments to tighten and lens to flatten
61
lens accommodation reflex in near vision
ciliary muscle contracts
ligaments relax
lens adopts a spherical shape
62
what cranial nerve is responsible for the lens accommodation reflex?
CNIII
63
three types of lacrimation
1. basal tears
2. reflex tears
3. emotion
64
what bones make up the orbit?
```
frontal
zygomatic
maxillary
sphenoid
ethmoid
lacrimal
```
65
which bones have orbital plates?
frontal
ethmoid
maxillary
66
what are orbital plates?
areas of thinner bone that are more likely to fracture
67
what is a blow-out fracture?
pressure is transferred to orbital plates causing fracture
68
what is a trapdoor fracture?
contents such as fat, muscle, nerves can herniate through a blow-out fracture
69
location of the optic canal in the orbit?
posteromedial
70
which bone is the superior orbital fissure found?
sphenoid bone
71
what does the superior orbital fissure allow passage of?
CNIII
CNIV
CNVI
72
what is the external eyelid composed of?
orbicularis oculi
73
what are the two parts of orbicularis oculi and their roles?
orbital (screwing shut)
| palpebral (gentle closure)
74
what is the internal eyelid composed of?
fibrous skeleton of superior and inferior tarsus with medial and lateral palpebral ligaments and orbital septum
75
what are tarsal glands?
glands in the eyelid that secrete lipids to line the eyelid and stop lacrimal fluid overflowing
76
where is the lacrimal gland located?
superolateral
77
what innervates the lacrimal gland?
CNVII
78
what does the lacrimal gland do?
produces fluid that passes into the cornea and washes over it collecting medially at the lacrimal lake
79
where does the lacrimal gland fluid drain?
lacrimal puncta into canaliculi through the lacrimal sac into the nasolacrimal duct (inferior nasal meatus)
80
pathway of sympathetic innervation to the head and neck
AP exit T1 and ascend within the sympathetic chain to superior cervical sympathetic ganglion
travels with ICA and ECA following opthalmic artery into the orbit
81
what are the four parasympathetic ganglia in the head and neck?
ciliary
pterygopalatine
otic
submandibular
82
what cranial nerve synapses in the ciliary ganglia?
CNIII to become the ciliary nerve
83
what do the meninges cover?
brain and spinal cord
84
layers of the meninges
dura mater (CNV)
arachnoid mater
sub-arachnoid space
pia mater
85
what level does the spinal cord end?
L2
86
what level does the subarachnoid space end?
S2
87
describe circulation of CSF
1. secreted by choroid plexus in lateral and third ventricles
2. flow into 4th ventricle via the cerebral aqueduct
3. drains into sub-arachnoid space and is reabsorbed by arachnoid granulations
4. passes into dural venous sinuses
88
why do people with raised ICP report visual symptoms?
optic nerves are also covered by the meninges
pressure is transmitted and can compress the nerve, central artery or vein of the retina
leads to papilloedema
89
CNIII oculomotor nerve palsy cause
compressed due to herniate of the uncal (medial lobe)
90
presentation of oculomotor nerve palsy CNIII
```
slowed light reflex
dilated pupil
ptosis
eye down and out
loss of accommodation
```
91
what can damage the CNVI?
stretching as it runs through the dura
92
presentation of CNVI palsy
eye is unable to move lateral causing medial deviation
93
presentation of CNIV palsy
on adduction there is upwards movement as IO is unopposed
