Anatomy Flashcards
1
Q
What makes up the roof border of the orbit
A
The frontal plate of the frontal bone and the lesser wing of the sphenoid
2
Q
Role of the roof border
A
separates the orbit from the anterior cranial fossa
3
Q
What makes up the lateral border of the orbit
A
The zygomatic bone and the greater wing of the sphenoid
4
Q
role of the lateral border of the orbit
A
separates the temporal fossa from the orbit
5
Q
What makes up the floor of the orbit
A
maxillary bone and the zygoma
6
Q
role of the roof of the orbit
A
separates the orbit from the maxillary air sinuses
7
Q
role of the medial border of the orbit
A
separates the orbit from the ethmoidal air sinuses
8
Q
what makes up the medial border of the orbit
A
the maxilla, the orbit plate of the ethmoid, the body of the sphenoid and the lacrimal bone
9
Q
what is the apex of the orbit and what does it contain
A
the orbit canal and it contains the optic nerve and ophthalmic artery
10
Q
orbital blow out #
A
medial and inferior walls are thin so a direct blow may cause a #
11
Q
risks of a medial orbit wall #
A
ethmoidal and sphenoidal sinuses may be involved
12
Q
risks of a inferior wall #
A
the maxillary air sinuses may be involved and the infraorbital nerve which can cause altered sensation of cheek. May also have diplopia.
13
Q
What does an eye lowered to the inferior orbital floor and diplopia suggest?
A
zygoma # which has rotated medially
- remember the suspensory ligaments are attached laterally to the zygoma
14
Q
The layers of the eyelid from superficial to deep
A
skin and superficial fascia orbicularis occuli tarsal plates levator apparatus conjunctiva
15
Q
Parts of the orbicularis occuli muscle
A
orbital part and the palpebral part
16
Q
innervation of the orbicularis occuli
A
facial nerve CNVII
17
Q
role of the orbicularis occuli muscle?
A
orbital part - tightly close the eye
palpebral part- gently close eyelid
18
Q
What is the orbital septum and where is it found?
A
sheet of fascia between the orbicularis occuli and the tarsal plates that helps prevent the spread of infection from superficial to deep
19
Q
What are tarsal plates?
A
2 plates deep to the palpebral region of the orbicularis muscle. 2 plates: superior tarus (upper eyelid) and the inferior tarus (lower eyelid)
20
Q
role of the tarsal plates
A
contain tarsal glands(Meibomian gland) that secrete an oily substance to keep the eyes moist and prevent them sticking when eyes are closed
also give structure
21
Q
what is the levator apparatus
A
2 muscles that act to open the eyelid: levator palpebrae superialis (LPS)and the superior tarsal muscles
only present in the upper eyelid
22
Q
role of the LPS and innervation
A
opens the eyelid and is innervated by the oculomotor nerve CNIII
23
Q
Location of the superior tarsal muscle, innervation and role
A
Underneath the LPS
assists the LPS in opening the eye
sympathetically innervated
24
Q
what is conjunctiva
A
thin mucous membrane folded onto the sclera
25
What is the pupil?
gap in the iris which allows light to be passed through before being focused on the retina
26
What is the limbus?
where the cornea and sclera meet- the corneascleral junction
27
what secretes lacrimal fluid and where is it secreted?
lacrimal gland
| secretes fluid onto the conjunctiva and cornea of the eye
28
where is the lacrimal gland located?
anterior in the superiolateral aspect of the orbit in the lacrimal fossa (depression in the frontal bone)
29
what innervates the lacrimal gland
parasympathetic CNVII
30
direction of travel of lacrimal fluid
fluid is produced in the lacrimal gland and is washed over into the medial angle of the eye where in travels through the lacrimal punctuae into the canaliculi into the lacrimal sac then into the nasolacrimal duct where it eventually meets the inferior meatus.
31
location of the nasolacrimal duct
in a groove formed by the lacrimal and maxilla
32
How many layers of the eye are there? What are there names?
3:
fibrous (outer)
Uvea (middle)
Retina (inner)
33
What is contained in the fibrous layer and what is their role?
Sclera and cornea
sclera: muscle attachment
cornea: major refractive power
34
What is in the uvea (and their function) and what is characteristic about the uvea?
VVVV vascular
Iris: controls pupil diameter and consequently how much light in
choroid: gas and nutrient exchange
ciliary body: contains ciliary muscles for accommodation and secretes aquaeous humour
35
What is included in the retina and what is the function
fovea
Optic disc: where the optic nerve enters
macula
36
What is the difference between the anterior segment and posterior segment?
Anterior segment is infront of the lens, the posterior segment is behind the lend
37
What is the posterior segment filled with
virteous humour
38
how is the anterior segment divided and what is it filled with?
Anterior chamber: between iris and cornea
Posterior chamber: iris and suspensory ligaments
both filled with aqueous humour
39
Differences in production between aquaeous humour and virteous humour?
Aquaeous is continuously produced whereas virteous is not
40
Circulation of aquaeous humour
Secreted by ciliary body into the posterior chamber and nourishes the lens.
it then travels through the pupil into the anterior chamber and nourishes the cornea and is then reabsorbed at the canal of schelmn @ iridocorneal angle.
41
blood supply to the eye and main branches
ophthalmic artery (branch of int carotid)
2 main branches:
central artery of the retina (end)
Ciliary arteries
42
why is the central artery of the retina so important?
its an end artery so occlusion leads to blindness vvv quickly
43
venous supply to orbit
superior and inferior ophthalmic veins
the inferior mainly drains into superior vein and they both then drain into the cavernous sinus
the facial vein also does a tiny amount
44
what is the danger triangle
between eyes over nose and down to upper lip... abscess here would be drained back into the cavernous sinus and couls cause a cavernous sinus thrombosis which is life threatening
45
What is the optic disc and where is it located?
located medially on the posterior wall of the retina. it is where the optic nerve CNII leaves the eyeball and where arteries/ veins enter/leave. (no photoreceptors)
46
Where is your blind spot?
optic disc
47
Where is the macula and what is the function?
Just lateral to the optic disc and has the greatest density of cone cells so v important for light vision.
48
Where is the fovea and what is its function?
just lateral to the optic disc in the centre of the macula. it is must important for vision acuity (sharp images not blurred)
49
How many extraocular muscles are there and what are they called?
```
7
superior rectus
inferior rectus
medial rectus
lateral rectus
superior oblique
inferior oblique
1 levator palpebrae superioris
```
50
Attachments of extraocular muscles
all originate from the common tendinous ring and attach onto the sclera
51
what is the somatic motor innervation of the extraocular muscles
LR6
SO4
AO3
52
Innervation and clinical test of lateral rectus
abduction into the same plane and the sup and inf rectus
| CNVI
53
Innervation and clinical test of superior rectus
Elevates eye when it is abducted
| CNIII
54
innervation and function of inferior rectus
CNIII
| when the eye is abducted it depresses the eye
55
innervation and clinical test of medial rectus
innervated by CNIII
| adducts the eye
56
innervation and clinical test of inferior oblique
elevates the eye when it is adducted
| CNIII
57
innervation and clinical test of superior oblique
depresses the eye when it is adducted
| CNIV
58
muscles involved in pure elevation
inferior oblique and superior rectus
59
muscles involved in pure depression
inferior rectus and superior oblique
60
What is the sensory innervation of the face and the divisions
```
Trigeminal nerve CNV
it has 3 divisions:
CNV1: opthalmic
CNV2: maxillary
CNV3: Mandibular
```
61
What is the name of nerve V1 and what it innervates
Opthalmic:
- upper eyelid
- cornea
- conjunctiva
- skin down centre of nose
62
Name of nerve V2 and what it innervates
Maxillary:
- side of nose
- lower eyelid
- skin of lower lip
- maxilla
63
Name of nerve V3 and what it innervates
Mandible:
- bottom lip
skin over mandible and temporomandibular joint
64
What innervates the temporomandibular joint
Supplied by spinal nerves C2 and C3
65
Explain the corneal Reflex:
Sensory/Afferent:
AP conducted from cornea via CNV1 to terminal ganglion then along CNV to pons
There is a CNS connection between CNV and CNVII
Motor/Efferent:
AP conducted along CNVII to the palpebral part of the occularis occuli to cause blinking
66
where do sympathetic axons exit the spinal cord
T1-L2 spinal nerves
67
How is sympathetic outflow describes
Thoracolumbar
68
What are splanchnic nerves
supply blood vessels and visceral organs (symp axons)
69
How do sympathetic axons from the spinal cord reach the orbit
pre synaptic sympathetic axons leave the spinal cord at T1 spinal nerve and ascend upwards with the sympathetic trunk and synapse in the superior cervical sympathetic ganglion.
post synaptic sympathetic axons enter the internal and external carotid nerves and pass onto the surface of internal and external carotid arteries. they are carried to the organs of head and neck on the surface of the branches of the internal and external carotid arteries. the ophthalmic artery carries sympathetic axons in the orbit.
70
What artery carries sympathetic axons to the orbit
ophthalmic artery
71
What cranial nerves are parasympathetic
X, IX, VII, III
72
how is the parasympathetic supply described
Craniosacral
73
Where does CN III synapse
ciliary ganglion
74
where does CN VII synapse
synapses in pteygopalatine ganglion and the post synaptic fibres travel to the lacrimal gland
75
where does the parasympathetic sacral spinal nerves innervate
hindgut
pelvis
peroneoum
76
What is the name of CN III
Oculomotor
77
Is CN III motor or sensory?
Motor
78
Is CN III sympathetic or parasympathetic?
Parasympathetic
79
Route of CN III
passes through the cavernous sinus, exits via superior orbital fissue and enters orbit
80
Where does the oculomotor supply somatic motor supply to?
```
SR
IR
MR
IO
LPS
```
81
Where does CN III synapse and what occurs after synapse?
Synapses at ciliary ganglion
gives off 2 division superior and inferior
superior innervates: SR, LPS
inferior innervates: IR, IO, MR and ciliary ganglion
82
What does the autonomic (sympathetic) axons in the ciliary nerve control
Diametre of iris
refractive shape of lens
(sympathetic innervates the sphincter papillae muscles)
83
Difference in short and long ciliary nerves
long: sympathetic and somatic sensory
short: sympathetic and parasympathetic
84
what are the autonomic reflexes of the eye
```
wide eye opening
pupillary dilation/constriction
accommodative reflex
lacrimation production
vestibulooccular reflex
occulocardiac reflex
```
85
What the sympathetic reflexes in the eye
OPens eye wider
get more light into eyes
focus on far objects
emotional lacrimation
86
what reflexes are the parasympathetic reflexes in the eye
```
Get less light into eye
focus on near objects
reflex lacrimation (foreign body)
```
87
What muscle is responsible for the opening eyes wider response
LPS
88
What muscle does the LPS contain and what is the innervation
Smooth and skeletal muscle
the skeletal muscle is innervated by the oculomotor nerve
the smooth muscle is sympathetically innervated to allow allow fight or flight
89
how do the sympathetic fibres reach the LPS muscle
leave the spinal cord and travel to the superior cervical sympathetic ganglion then axons travel via the internal carotid artery via a plexus then the artery divides and the axons are carried on the ophthalmic artery
90
What nervous system causes pupillary dilation and in what scenario does it happen
SYMPATHETICS
| in dim light, flight or fight or if PT is sick
91
what is a mydriatic pupil and what causes it
Non physiologically enlarged pupil
| mydriatic drug
92
what fibres causes pupil dilation and how
dilator pupillae fibres (originate around the external circumference of the iris and insert around the internal circumference of iris)
supplied by the symp nervous system- contraction of the pupillae causes pupil dilation
93
What nervous system causes pupil constriction and in what scenario does it happen?
Parasympathetic
| occurs in bright light and rest and digest
94
what is a miotic pupil and what is it a component off
non-physiologically enlarged pupil
| component of horners syndrome
95
What can a fixed dilated or fixed pin point pupil suggest
fixed dilated: CN III pathology
| fixed pin point: opiates
96
what muscles cause pupil constriction
sphincter pupillae fibres encircle the pupil and there contraction causes constriction
97
what is the pupillary light reflex and the mechanism
when a light is shone in one eye it causes bilateral constriction
Sensory: signal sent by the optic nerve (CN II: IPSILATEAL)
CNS connections occur in midbrain
Motor: signal is bilateral along CNIII (oculomotor)
98
what is the direct light reflex
constriction in the eye stimulated with light
99
what is the consensual light reflex
constriction in the non stimulated eye
100
what is the 4 neurone chain of the pupillary light reflex
1) retinal ganglion cells send an AP via the ipsilateral optic nerve which crosses at the optic chiasm and synapses in the pretectal nucleus
2) located in midbrain and connects the pretectal nucleus to the next synapse the Edinger Westphal nucleus (bilateral )
3) pass from the EW nucles to the CNIII then to its inferior division to synapse in the ciliary ganglion
4) course in the short ciliary nerves to the sphincter papillae muscles
101
what is the refractive power of the lens vs the cornea?
cornea: 2/3 of refractive power
lens: 1/3 of refractive power
102
what connects the lens and ciliary body
suspensory ligament of lens
103
what controls the shape of the lens
parasympathetic
104
describes what happens in relaxation of the ciliary muscles
relaxation of the ciliary muscles puts tension on the suspensory ligaments causing the lens to flatten out
happens in long vision
happens when the parasympathetic supply is switched off
105
describe what happens in contraction of ciliary muscles
contraction of the ciliary muscles causes the suspensory ligament to relax and the lens to become spherical
occurs in short vision
happens under parasympathetic stimulation
106
what shape of lens has a greater refractive e power
spherical has a greater refractive power than flat
107
what is the natural position of your lens
spherical
108
why do people need reading glasses as they get older
lens becomes less flexible and more fibrous so cannot spring into sphere as easily
109
what is the accommodative light reflex and why is it needed
changing focus distance
if looking at something in the distance the cornea does enough light bending to focus an image on the retina whereas close up the cornea is not enough to bend an image and the lens in needed
110
how do you clinically asses the accommodative reflex
ask the patient to look at something in the distance and then to quickly look at something very close in the midline
111
what 3 components are assessed in the accommodative reflex:
1) bilateral pupillary constriction
2) bilateral convergence
3) bilateral relaxation of lens
112
what are the 3 types of lacrimation
1) basal
2) reflex
3) emotional
113
what are basal tears
constant tears that clean and nourish cornea. also contain lysosome the enzyme that degrades bacterial cell walls.
114
what are reflex tears
tears in response to mechanical or chemical stimulation. afferent in CN V1 and efferent is CN VII (autonomic parasympathetic)
115
what is horners syndrome and what are the symptoms
horners is impaired sympathetic innervation to the head and neck
symptoms are ipsilateral: miosis, ptosis, reduced sweating and inc warmth and redness
