Basic Ophthalmology Anatomy Flashcards
what are the 7 bones of the orbit?
frontal zygomatic maxilla lacrimal ethmoid sphenoid palatine bones
what are the important entrance/exit points in the bony anatomy of the orbit?
supraorbital foramen/notch infraorbital foramen superior orbital fissure inferior orbital fissure optic canal
what passes through the supraorbital foramen/notch?
supraorbital nerve and vessels
what passes through the infraorbital foramen?
infraorbital nerve and vessels
what passes through the superior orbital fissure?
CN III
CN IV (trochlear - superior oblique)
CN V1
CN 6 (abducens - lateral rectus)
what passes through the optic canal?
CN 2
where is the optic canal found?
on posterior wall
medial to superior orbital fissure
what is the area where the iris meets the sclera called?
corneal limbus
how many lacrimal puncta are there and where do they lead to?
2
- one on upper lid - drains into superior lacrimal canal > nasolacrimal duct
- one on lower lid - drains into inferior lacrimal puncta > nasolacrimal duct
where is the lacrimal gland found?
superior and lateral to the eye (brow bone)
what are the 2 types of conjunctiva?
tarsal conjunctiva = lines inner surface of eyelid
bulbar conjunctiva = lines sclera up until the corneal limbus
what are the 2 cavities of the eye and what do they consist of?
anterior cavity
- anterior chamber = between cornea and iris
- posterior chamber = between iris and lens
posterior cavity
- contains vitreous chamber
what are the 3 groups of extraocular muscles?
rectus muscles
oblique muscles
levator palpebrae superioris
what are the 3 intraocular muscles?
ciliary muscles
sphincter pupillae
dilator pupillae
where is the trochlea found?
superior nasal aspect of the frontal bone within the orbit
on which side of the eye does the inferior rectus attach?
lateral
2 main actions of the superior oblique?
how can this be tested?
moves eye ball down and in which leads to looking down and out
intorsion when looking straight ahead
tested by making patient look down and in
3 main actions of inferior oblique?
extorsion
elevation
abduction
how is the action of inferior oblique tested?
make patient look up and in
why does testing of the oblique muscles not match their function?
as their elevation/depression functions are strongest on adduction
the ciliary muscles are part of what?
part of ciliary body
what do the ciliary muscles do?
act as part of accommodation reflex
contraction causes relaxation of suspensory ligaments and allows lens to thicken allowing focus to shift to close up objects
what do the sphincter pupillae muscles do?
also activate in accommodation reflex as well as the light reflex to constrict the pupil
what do the dilator pupillae muscles do?
increase diameter of the pupil
are the intraocular muscles under sympathetic or parasympathetic control?
ciliary and sphincter pupillae muscles = parasympathetic
dilator pupillae = sympathetic
what nerve is responsible for special sensory (vision) in the eye?
CN 2 (optic)
sensory innervation of the eye?
CN V1
motor innervation of the eye?
CN III CN IV (trochlear = superior rectus) CN VI (abducens = lateral rectus)
how is the autonomic nervous system involved in the eye?
sympathetic fibres from internal carotid plexus
parasympathetic fibres from edinger westphal nucleus, carried in CN III to ciliary ganglion
sign of CN III palsy?
eye fixed in down and out position
dilated (blown) pupil
sensory control of the cornea?
CN V1
how does CN II provide special sensation of vision?
both optic nerves converge at the optic chiasm where information is exchanged, dividing visual information into right and left visual field, rather than right and left eye
nasal retinal fibres (temporal visual field) cross over to the contralateral side of the brain and join temporal retinal fibres (nasal visual field) which do not cross
these mixed fibres form the optic tract
how do the optic tracts travel to the primary visual cortex?
information on the left and right visual fields continue to the lateral geniculate nucleus of the thalamus
from here information is split again into superior and inferior visual fields
- superior visual fields reach the primary visual cortex via the temporal lobe (Meyers loop)
- inferior visual fields will reach the primary visual cortex via the parietal lobe
what are the 3 parts of the accommodation reflex?
convergence
thickening of lens
pupillary constriction
what nerves mediate the pupillary light reflex?
afferent pathway = CN II (optic)
efferent pathway = CN III (oculomotor)
2 divisions of pupillary light reflex?
direct
consensual
what is the corneal reflex?
eyes should close in response to a physical stimuli stimuli applied to the cornea
what nerves mediate the corneal reflex?
afferent pathway = CN V1
efferent pathway = CN VII
describe blood supply to the eye
ophthalmic artery branches off internal carotid (1st branch)
ophthalmic artery branches to:
- central retinal artery = enters via optic nerve and supplies inner retinal layers
- posterior ciliary artery = enters eye outside of optic nerve and supplies middle and outer retinal layers
