Anatomy Flashcards
What forms the apex of the orbit?
Optic canal
What bones form the lateral wall of the orbit?
Sphenoid
Zygomatic
What bone forms the floor of the orbit?
Maxilla
What bones form the medial wall of the orbit?
Lacrimal
Ethmoid bone
Frontal bone
Maxilla
What bone forms the roof of the orbit?
Orbital plate of the frontal bone
What is an orbital blow out?
Direct blow to eye can fracture the maxilla or ethmoid bone resulting in infraorbital neurovascular bundle damage
What nerve passes through the infraorbital foramen?
Facial nerve - causes sensory loss to skin
What features of the eyelid protects the eye?
Outer skin
Inner conjunctiva
Eyelashes
Glands
What is contained within the eyelid?
Tarsal plate (maintains shape) and meibomian lands to secrete lipids
Orbicularis oculi
Levator palpebrae superioris
What innervates the orbicularis oculi?
Facial nerve
What innervates the levator palpebrae superioris?
Parasympathetics from oculomotor nerve
What is the limbus?
Corneoscleral junction
What covers the white sclera?
Conjunctiva
What covers the iris?
Cornea
What gland produces lacrimal fluid?
Lacrimal gland situated in the upper outer quadrant of the orbit below the eyebrow
What is the pathway of lacrimal fluid from the lacrimal gland?
Supplied by facial nerve
Fluid washes over eye
Pushed towards medial angle
Drains through lacrimal puncta through the canaliculi canal to the lacrimal sac
Will drain through the nasolacrimal duct to the inferior meatus of the nasal cavity
What forms the fibrous layer of the globe?
Sclera - white and fibrous
Cornea - transparent and allows for refraction of light
What forms the uvea of the globe?
Iris - pupil diameter
Ciliary body - controls iris, shape of lens and secretion of aqueous humour
Choroid - nutrition and as exchange
What forms the retina?
Macula
Optic disc
Where is the anterior segment of the eye situated?
In front of lens
Divided into anterior and posterior chambers
What is contained within the anterior chamber of the anterior segment of the eye?
Between cornea and iris
Contains aqueous humour
What is contained within the posterior chamber of the anterior segment of the eye?
Between iris and suspensory ligament and contains aqueous humour
Where is the posterior segment of the eye situated?
Behind lens
2/3rd of eye
What is contained within the posterior segment of the globe?
Vitreous body
Vitreous humour
Common location for floaters
Can vitreous humour be made?
No, it is not produced in the eye, if it is damaged it will not come back
Can aqueous humour be made?
Yes, it is made in the ciliary process of the eye
What is the flow of aqueous humour in the eye?
Made in the ciliary process of the ciliary body
Circulates within the posterior chamber and nourishes lens
Passes through pupil into the anterior chamber to nourish the cornea
Reabsorbed into the scleral venous sinus via the canal of schlemm at the iridocorneal angle
What is the iridocorneal angle of the eye?
Angle in open angle and closed angle glaucoma
Raised intraocular pressure can cause ischaemia of the retina and glaucoma
What artery supplies the orbit?
Ophthalmic artery which is a branch of the internal carotid artery
What is contained within the optic canal?
Optic nerve and ophthalmic artery
What artery and vein run through the optic nerve?
Retinal artery and vein
What veins drain the eye?
Superior and inferior ophthalmic vein which drain into cavernous sinus via the superior orbital fissure
Orbit also drains anteriorly into facial vein
What is the fundus?
Posterior area of retina where light is focused
What is contained within the fundus?
Optic disc
Macula
Fovea
What occurs at the optic disc?
Point of optic nerve formation
Only point of entry/exit for blood vessels and axons of optic nerve
Blind spot
What is contained within the macula?
Yellow area that has the greatest density of cones allowing for colour vision and the area of vision acuity
What is the fovea?
Centre of the macula which is the area of most acute vision
What are the 3 main layers of the retina going posterior to anterior?
Most posterior: photoreceptors
Middle: Ganglion cells
Anterior: Axons of the ganglion