The orbit and the Eye Flashcards
Describe the papyrcea
medial wall containing sinuses
Describe the function of the orbital rim
thick wall, good at protecting the eye unless there is exophthalmos or piercing object
What is the risk with a blowout fracture?
Damage the infraorbital neurovascular bundle; resulting in a sensory deficit
What causes a blowout fracture?
Pressure increase inside the orbit rises dramatically, inferior or medial bones will fracture to release pressure
What are the four components of the eyelids?
Outer skin
Inner conjunctiva
Eyelashes
Glands
What is the function of the tarsal plate ?
Maintains shape and contains meibomian glands
What is the role of meibomian glands?
secrete lipids
What is the innervation pattern of obicularis oculi?
facial nerve
What is the result of obicularis oculi contraction?
closure of the eye
What does occulomotor nerve palsy result in?
Not be able to open your eye- ptosis
What is the limbus?
Corneoscleral junction
Which layers of the eye are continuous?
Cornea and sclera
What nerve is responsible for production of tears?
Parasympathetic CN 7 (facial)
What is the function of tears?
Wash over eye - lubrication
Describe the sclera?
White fibrous layer
Describe the function of the cornea?
refraction
What is the uvea?
Vascular middle layer
- iris
- ciliary body
- choroid
What is the function of the iris?
Control pupil diameter
What is the function of the ciliary body?
Controls iris, shape of lens, secreted aqueous humour
What is the function of the choroid?
Nutrition and gas exchange
Why does the choroid appear black?
Vasculature and melanin
What is the function of the retina?
Photosensitive inner layer containing rods and cones
What is the anterior chamber of the eye ?
Infront of lens; between cornea and iris
Contains aqueous humour
What is the posterior chamber of the eye?
Behind lens
Contains vitreous humour
Where is a common location for floaters?
Posterior segment of the eye
List the steps in circulation of aqueous humour?
- Ciliary body
- smooth muscle and blood vessels, ciliary processes secrete aqueous humour - Aqueous circulates
- within posterior chamber, nourishes lens - Aqruous passes though pupil
- into anterior chamber and nourished cornea - Aqueous reabsorberd
- into scleral venous sinus (canal of schlemm)
- at iridocorneal angle
List the layers of the retina from posterior to anterior?
- Photoreceptors
- Ganglion cells
- Axons of ganglion cells
What is the optic disc?
Point of CN II formation
only point of exit/entry for blood vessels and axons of CN II
blind spot
What is the macula?
Area with greatest density of cones
What is the fovea?
Centre of the macula
Depression, 1.5mm diameter
Area of most acute vision
What does complete interruption of flow in a retinal artery branch/vein cause?
Loss of area of visual field corresponding to the area of ischaemia
What causes monocular blindness?
Complete interruption of flow from the central artery or vein
Which extrinsic muscles of the eye are innervated by the oculomotor nerve?
Medial Rectus
Superior Rectus
Inferior Rectus
Inferior Oblique
Which extrinsic muscle of the eye is innervated by the abducens nerve?
Lateral rectus
Which extrinsic muscle of the eye is innervated by the trochlear nerve?
Superior oblique
Describe the function of the lateral rectus?
Abduction of the eye
Describe the function of the medial rectus?
Medial movement of the eye
Describe the function of the superior rectus?
Up and in
Describe the function of the inferior rectus?
Down and In
Describe the function of the superior oblique?
Down and out
Describe the function of the inferior oblique?
Up and out
