Anatomy of the Orbit and Eye Flashcards
name the bones of the orbit
frontal ethmoid maxilla zygomatic sphenoid lacrimal
the nasal bone does not make up the orbit: T or F?
T
how many bones contribute to the orbit?
6
what is the function of the supra/infraorbital foraminae?
allow passage of supra/infraorbital neurovascular bundles
what shape is the orbit considered to take?
pyramidal shape
what makes up the apex of the pyramidal shape of the orbit?
optic canal
what makes up the floor of the orbit?
maxilla
what makes up the medial wall of the orbit?
ethmoid
what makes up the lateral wall of the orbit
sphenoid
what makes up the orbital rim?
superior, inferior, medial, lateral margins of the orbit
what protects the eye from direct damage?
the orbital rim
which is more anterior: superior orbital margin or inferior orbital margin
superior
what makes up the superior margin of the orbit
frontal
what margins of the orbit are at risk of an orbital blowout fracture?
medial wall floor
symptoms of an orbital blowout fracture?
loss of sensation in face sight problems
what is diplopia?
double vision
what constitutes the most external layer of the eyelid?
orbicularis oculi muscle
name the 2 parts of the orbicularis oculi muscle and their location?
orbital= goes round whole orbit
palpebral= lower eyelid
what does the middle layer of the eyelid contain
orbital septum (fascia) ligaments
main role of the orbital septum?
prevent infection
which muscle of the eyelid allows the eye to screw up?
orbital part of the oculi
what are tarsi
half moon bands of connective tissue that make up the eyelids
what muscle is responsible for lifting the eyelid up?
levator palpebrae superioris
another name for mueller’s muscle?
superior tarsal muscle
which part of the eye is avascular?
cornea
what is the white of the eye called?
sclera
what covers the white of the eye?
conjunctiva
where is the lacrimal gland located?
laterally on the brow bone
name the part of the eye that contains your eye colour
iris
what is the limbus
the grey area surrounding the iris and the sclera
what is the cornea?
translucent covering of the iris
the conjunctiva does not cover the cornea: T or F?
T
what is the dot on the medial lower eyelid called?
punctum
why do we get runny noses when we cry?
tears drain via the lacrimal sac into the nasolacrimal duct which reaches inferior meatus in nose
what nerve controls production of lacrimal fluid by the lacrimal gland?
CN VII
name the 3 layers of the eye
fibrous
uvea
retina
name the 2 parts of the fibrous layer of the eye
cornea
sclera
main source of refractive power of the eye?
cornea
3 main components of the uvea?
iris
ciliary body
choroid
what does the iris control?
diameter of the pupil
what does the ciliary body control?
iris
shape of lens
secretion of aqueous humour
which layer of the eye contains its vasculature?
uvea
what separates the anterior and poster segments of the eye?
the lens
which segment of the eye contains vitreous humour?
posterior
which segment of the eye contains aqueous humour?
anterior
how does the cornea get nutrition if it doesn’t have a blood supply?
via the lacrimal gland and aqueous fluid
name a common area of the posterior segment for floaters and why
vitreous body as vitreous humour is very gel like so can stick
what is a cataract?
clouding of the lens
what is closer to the iris:
the iridocorneal angle or limbus?
iridocorneal angle
what is responsible for the pressure of the eye?
aqueous humour
describe the path of aqueous humour from its production
secreted by ciliary processes
circulates in posterior chamber to nourish lens
passes into anterior chamber to nourish cornea
reabsorbed at the iridocorneal angle by the scleral venous sinus
blood supply to the uvea?
ciliary artery
consequences of raised intra-ocular pressure?
ischaemia of the retina
glaucoma
main arterial supply to the eye?
opthalmic artery
what is the opthalmic artery a branch of?
internal carotid artery
name the artery that travels through the centre of the optic nerve?
central artery of the retina
why can occlusion of the central artery of the retina cause ischaemia?
it is an end artery
main blood supply to the retina?
central artery and vein of the retina
name the different routes of venous drainage of the eye
via superior/inferior opthalmic veins -> cavernous sinus
anteriorly into the facial vein
how can an infection of the upper lip/external nose cause an infection of the brain?
infection will drain into the facial vein
what is the back of the eye called?
fundus
at what part of the retina does the optic nerve form?
CN 2
which part of the retina does not contain photoreceptors?
optic disc
what part of the retina is known as the blind spot?
optic disc
what part of retina contains the most cone cells and why?
macula, needs them for acute vision
where is the fovea located?
centre of macula
name the layers of the retina from anterior to posterior
A Good Photo
axons of the ganglion
ganglion
photoreceptors
is the optic disc located more on the nasal or temporal side on fundoscopy?
nasal
consequence of complete interruption of flow in a retinal artery/vein?
loss of an AREA of visual field
consequence of complete interruption of flow of the central artery or vein?
monocular blindness
what area of both eyes would light from the right visual field hit?
right eye- nasal side
left eye- temporal side
what area of both eyes would light from the left visual field hit?
left eye- nasal
right eye- temporal
what part of the visual cortex is light from the right and left visual fields processed by?
right visual field- left primary visual cortex
left visual field- right primary visual cortex
whichever eye has used the nasal retina to absorb the light will be the side of the visual cortex used
how may extraocular muscles are there?
7
are the extraocular muscles of the eye skeletal or smooth muscle?
skeletal
name the 4 rectus muscles
superior rectus
inferior rectus
medial rectus
lateral rectus`
origin of the rectus muscles?
common tendinous ring
insertion of the rectus muscles?
sclera
name the non-rectus extraocular muscles
superior oblique
inferior oblique
levator palpebrae superioris
name the somatic motor innervation of the extraocular muscles (use mnemonic)
LR6 (lateral rectus = CN6)
SO4 (superior oblique = CN 4)
AO3 (all others = CN3)
what plane would the eyes move if the were on the vertical axis?
they would abduct and adduct as they would move horizontally
in what direction would the eyes move if they were on the transverse axis?
elevation/depression as they would be moving up and down (transverse=horizontal)
what direction would eyes move if they were in the anteroposterior axis?
intorsion
extorstion
how do you isolate eye muscles so you know you’re only testing one muscle?
line up eye gaze to the plane being tested
name the 3 axes of the eyeball
transverse
anteroposterior
vertical
what does the lateral rectus muscle do/
abducts eyeball
how can you solely test for superior/inferior rectus function?
ask patient to abduct eye to get it in the right plane
ask them to elevate/depress eye
what muscles can be isolated when you ask the patient to adduct the eye?
infraorbital- ask to elevate
supraorbital- ask to depress
what muscles of the eye are responsible for elevation?
superior rectus
inferior oblique
what muscles of the eye are responsible for depression?
superior oblique
inferior rectus
name the components of the uvea from anterior to posterior
iris
ciliary body
ciliary vein
2 muscles in charge of pupil size?
dilator pupillae
sphincter pupillae
what part of the retina will light from the above part of the visual field go to?
lower nasal
