Anatomy Flashcards
What two parts of the eye are mentioned as being extremely thin and are often affected in an orbital blowout fracture?
the medial wall of the orbit & orbital floor
Where does a fracture zygoma tend to rotate?
rotate medially towards the floor of the orbit
What assists with preventing the spread of infection from superficial (periorbital cellulitis) to deep (orbital cellulitis)?
orbital septum
Fibres of which muscle allow for screwing up the eye?
orbicularis oculi
What is the muscle that raises the upper eyelid?
tendon of levator palpebrae superioris
What attaches eyelid to orbital rim?
medial palpebral ligament
What is the iris covered by?
the translucent, avascular cornea
Where do tears go in blinking?
lacrimal lake then puncta
What is the lower eyelid lined by?
conjunctiva
Where is the conjunctiva reflected off the sclera and onto the internal aspect of the eyelid?
the conjunctival fornix
What does the conjunctiva form?
forms a defensive barrier to foreign bodies penetrating deep to it into the orbit
What is the limbus?
corneoscleral junction
What produces tears and what supplies this?
lacrimal gland
parasympathetic supply from CNVII
What is the superior end of the nasolacrimal duct?
lacrimal sac
What carries tears to the inferior meatus of the nasal cavity?
nasolacrimal duct (tear duct)
What are the nasal and temporal corneal reflections used to track clinically?
used clinically to track the symmetry of bilateral eye positions/movements
Name the two parts to the outer layer.
- the sclera (protective/attachment for extraocular muscles)
- the cornea (provides ~ 2/3rds of the eyes refractive power)
Name the 3 parts of the middle layer (the uvea).
- the iris (control of pupil diameter)
- the ciliary body (control of the iris, the shape of the lens & the secretion of aqueous humour)
- the choroid (nutrition & gaseous exchange for the other layers)
What is the inner retina composed of?
photosensitive & composed of many layers
What is the space between the cornea and the iris and what does it contain?
anterior chamber
contains humour
Where is the vitreous body and what does it contain?
posterior segment
contains gel to apply pressure to hold retina to choroid
What is the vitreous body a common location of?
floaters
Where is the posterior chamber?
between iris and vitreous body
What is clouding of the lens?
cataracts
Where is iridocorneal angle?
anterior chamber
inferior
Where is the aqueous reabsorbed?
reabsorbed into the scleral venous sinus (Canal of Schlemm) at the iridocorneal angle
Raised intra-ocular pressure can cause what?
ischaemia of the retina
What is the area of most acute vision: greatest density of cones?
the fovea centralis in the macula
What does the fundus consist of?
retina + macula + fovea centralis + optic disc
What forms at the optic disc?
CN II forms from all the axons leaving the retina
Where does the internal carotid artery enter?
the carotid canal in the temporal bone
What do nasal cavity branches contribute to?
Kiesselbach’s area
What does this describe: an artery with insufficient anastomoses to maintain viability of the tissue supplied if arterial occlusion occurs?
an end artery
What vessels are responsible for red eye in flash photography?
ciliary arteries and veins of uvea
What is the only point of entry into/exit from the retina for blood vessels & the axons of CN II?
optic disc
The “blind spot” of the visual field corresponds to what?
optic disc
Complete interruption of flow of the central artery (end artery) or vein leads to what?
monocular blindness
Complete interruption of flow in a retinal artery branch/”branch” retinal vein leads to what?
loss of an area of visual field corresponding to the area of ischaemia
Are there photoreceptors in the optic disc?
No
List the layers of the retina from posterior to anterior.
- photoreceptor cells
- the ganglion cells
- the axons of the ganglion cells
Light from objects in the right visual field is processed by what?
left primary visual cortex
Light from objects in the lower visual field is processed by what?
lower part of primary visual cortex
How many skeletal muscles does the eye have?
7
How many oblique muscles?
2 (superior and inferior)
How many rectus muscles?
4
Which muscle is the pulley of the superior oblique?
trochlea
Where do the rectus muscles all originate from?
common tendinous ring attached to the bones surrounding the optic canal
Where do the rectus muscles all insert into?
the sclera just posterior to the cornea
Lateral rectus is supplied by which nerve?
CN6 (abucens)
Superior oblique is supplied by which nerve?
CN4 (trochlear)
All other muscles are supplied by which nerve?
CN3 (oculomotor)
