Anatomy Flashcards
name the 7 bones of the orbit
frontal
zygomatic
maxilla
nasal
sphenoid
ethmoid
lacramal
which bone does the optic canal pass through?
sphenoid
in addition to the optic canal the sphenoid bone also contains what?
superior orbital fissure
what is the apex?
the optic canal
the roof, medial and lateral walls and the floor of the orbit make up the what?
orbital margins
the superior/inferior orbital margin is more anterior
superior orbital margin
(slopes forward with inferior more posterior)
trauma to the orbit results in what?
orbital blowout fracture
NOTE: bony rim protected but force travels to floor and fractures
when an orbital blowout fracture occur what can also be damaged?
intraorbital nerves- sensory to face (maxilla and wings of nose)
fractured zygoma tends to rotate which direction?
medially
the suspensory ligament of the eye attaches to what?
the zygoma laterally
if zygoma fractures and suspensory ligament drops what clinical sign can occur?
diplopia- double vision
what are the two parts of the eyelid that make up the orbicularis oculi muscle
orbital- around eye
palpebral- eyelid itself
what helps prevent spread of infection from superficial to deep in the eye?
orbital septum- sheet of fascia
what gland containing sturcture lies within the upper eyelid?
superior tarsus- tarsal glands embedded in tarsi
what is the limbus?
corneoscleral junction
what is the function of the conjuctiva?
forms defensive barrier to foreign bodies penetrating deep to it into the orbit
defien tarsus
dense connective tissue bands in half moon shape that give shape to the eyelid- superior/inferior
what is the name of the tendon attached to the superior tarsus responsible for lifting the eyelid?
levator palpebrae superioris
what is known as mullers muscle?
superior tarsal muscle attached to superior tendon that helps to lift the eyelid
glands in the tarsus secrete what?
lipids for lubraication
prevents tears overflowing in normal day to day life until youre actually crying
what nerve innervates teh lacrimal gland responsible for producing lacriaml fluid?
parasympathetic CNVII
describe the lacrimal apparauts
lacrimal gland produces lacrimal fluid
washes over eye towards medial angle
drained through lacrimal puncta
then canaliculi into lacriaml sac
finally drain into nasolacrimal duct
what are the three layers of the eye?
fibrous
uvea
retina
what are the two parts of the fibrous layer of the eye?
sclera
cornea
what makes up the uvea?
iris
ciliary body- controls iris and aqueous humor secretion
choriod- nutrition and gas exchange
the anterior/posterior segment of the eye is divided into chambers?
anterior segment divided into anterior/posterior chambers
where is the anterior chamber located?
between cornea and iris
where is the posterior chamber located?
between iris and suspensory ligaments
the anterior and posterior chambers contain what?
aqueous humour
the posterior segment of the eye is located where?
behind the lens- post 2/3rds
he posterior segment of teh eye contains what?
vitreous body- vitreous humour
vitreous body is common location for what pathology?
floaters
a clouding of the lens is known as what?
cataract
the ciliary body secretes what?
aqueous
describe the circulation of aqueous
circulates within posterior chamber
passes through the pupil into anterior chamber
aqueous reabsorbed into canal of schlemm
from which artery does the opthalmic artery arise?
internal carotid artery
through what stucture do the cnetral arerty and vein of the retina pass through?
optic nerve
what kind of artery is the central artery of the retina?
end artery- only one supplying tissue
the inferior opthalmic vein drains mainly into which vein?
superior opthalmic vein
the fundus includes what structures?
optic dsc
macula
fovea
the optic disc is the point of which nerve formation?
CN II
which structure ahs eh greatest density of cones?
macula
where is the fovea located?
centre of the macula- area of most acute vision
the optic disc is also the ____ ___
blind spot
name the retina layers from posterior to anterior
photoreceptors
ganglion cells
axons of ganglion cells
why is the optic disc a blind spot?
there are no photoreceptors in the ooptic disc
the retinal veins and arteries lie anterior to the retina true/false?
true
the retina is divided up how?
upper and lower nasal/temporal quadrants
complete interruption of flow of teh central artery or vein will result in what?
monocular blindness
complete interruption of flow in a retinal arter branch/retinal vein will result in what?
loos of an area of visual field corresponding to area of ischameia
light from objects in the right visual field is processed by the left primary visual cortex true/flase
true, light processed by opposite visual cortex
NOTE: light from objects in upper visual field processed in lower cortex and vice versa
name the 7 extraocular muscles
superior rectus
inferior rectus
medial rectus
lateral rectus
superior oblique
inferioroblique
levator palpebrae superioris
the rectus muscles all originate from where?
common tendinous ring
extracolular msucles insert where?
onto the sclera
what is the somatic innervation of the extraocular muscles?
LR6 SO4 AO3
lateral rectus- CN VI
superior oblique- CN IV
all others- CN III
most musclehave a secondary movement apart from which ones?
medial and lateral rectus
lateral rectus can only _____ the eyeball
abduct
in clinical testing of eye movement what do you have to do in order to test an individual eye muscle?
have to line up gaze with the muscle being tested
when in abduction SR can only ______ the eyeball
elevate
when in abduction the IR can only ______ the eyeball
depress
medial rectus can only _____ the eyeball
adduct
when in adduction IO can only ______ the eyeball
elevate
when in adduction the SO can only _____ the eyeball
depress
describe pure elevation and the action of the muscles involved (synergistic or antagonists)
SR and IO synergistically elevate eyes
antagonists as rotators
pure elevation
describe pure depression and the actions of the muscles involved? (synergistic/antagonists)
SO and IO synergistically depress eyes
antagonists as adductors/abductors
pure depression
which sensory nerve innervates each of the coloured areas?
purple- ophthalmic nerve CN V1
blue- maxillary nerve CN V2
pink- mandibular nerve CN V3
blink reflex is also known as what?
corneal refelx
which of sensory and motor neurones are afferent/efferent?
sensory = afferent
motor = efferent
APs from the cornea are conducted via what?
CN V1 branches
in the corneal reflex, central CNS connections are made between what?
CN V and CN VII
motor APs in the corneal reflex are conducted via what to the eyelid?
CN VII
skin provides sympathetic innervation of what?
arterioles of teh head
sweat glands
arrector muscles
descirbe the route of sympatheic axons
originates in autonomic centre of brain
exits spinal cord with T1-L2 spinal nerves
travel to sympatheic chains and pass into all spinal nerves
pass into splanchnic nerves to suplly organs
presynaptic sympathetic axons from CNS exit spinal cord level ___
T1
post-synaptic sympathetic axons enter internal and externla carotid nerves before passing onto the surface of what?
internal and external carotid arteries
which artery carries sympathetic axons to the orbit?
opthalmic artery
all parasympathetic nerves leave the CNS via which cranial nerves?
III, VII, IX, X via sacral spinal nerves
CN III passes through the ______ ___ before exiting through what?
passes through cavernous sinus before exiting via superior orbital fissure
ciliary nerves control what?
diameter of iris and refractive shape of the lens
what are long and short ciliary nerves?
long- sympathetic, somatic sensory
short- sympathetic, parasympathetic
long/short ciliary nerves form first part of blink relfex
long ciliary nerves
what is the accomodation reflex?
docussing lens far & near
vestibulo-ocular reflex deos what?
turns eyes in opposite direction to a head movement stabilizing gaze on a object during movement
descirbe the oculocardiac reflex
reflex bradycardia in response to tension on teh extraocular muscles or pressure on the eye
the levator palpebrae superioris contains skeletal and smooth muscle true/false?
true
what class of drug dilate the pupil?
mydriatic drugs
Note; a non-physiologically enlarged pupill is a mydriatic pupil
how are dilator pupillae fibres arranged?
radially originating around external circumference of the iris
what is a miotic pupil?
a non-physiologically constricted pupil
N.B. compomnent of horners syndrome
a fixed ‘pin point’ pupil is a serious sign and can be seen in?
opiate drugs
a ‘fix-dilated’ or blown pupil can be seen in what cranial nerve pathology?
CN III pathology
the sensory (afferent) limb of teh light reflex is ipsilateral/bilateral?
sensory (afferent) = ipsilateral
motor (efferent) = bilateral
the pupillary light reflex is a how many neurone chain?
4
describe the 4 neurones involved in the pupillayr light reflex
- retinal, passes via ipsilateral optic nervesynapsing in pretectal nucleus in midbrain
- connect pretectal nucleus to synapse in Edinger- westphal nucleus (bilateral)
- pass from EW via CN III synapsing in ciliary ganglion (bilateral)
- ciliary nerves to sphincter pupillae muscles (bilateral)
the ciliary muscle relaxes in near/far vision?
relaxes in far vision
constracts in near vision
what are the three clinically assessed components of the accomodaion reflex?
bilateral pupillary constriction
bilateral convergence of eyes to midline
bilateral relaxation of lens
the lens is flattened in near/far vision?
far vision
what are the three forms of tear?
basal
reflex
emotional
horners syndrome is a result of impairede ______ innervation to head and neck
impaired sympathetic innervation
what fibres encircle the pupil?
sphincter pupillae fibres
what muscle is respsonsible for relaxing and tightenong the lens?
ciliary muscle
