Flashcards in Anatomy of the Eye Deck (17):
What is the structure of the retina?
Optic disc - point of contact between retina and optic nerve - blind spot
Central retinal artery and vein within the optic nerve
What are the muscles of the eyelid?
To open: Levator palpebrae superioris (CN3) and the superior tarsal muscle (sympathetic nervous system)
To close: orbicularis oculi (CN7)
What nerves produce the corneal (blink) reflex?
CN V1 (sensory)
CN VII (motor)
Damage to CNV1 can lead to damage by corneal ulceration, dust and foreign objects aren't detected. In CN7 damage, there is no blinking, this can also dry the eyes out
In a fundoscopy, what can we see if there is an increase in ICP?
Venous engorgement and papilloedema (optic disc swelling)
Which structures pass through the supra-orbital fissure of the orbit?
Trochlear nerve (CN4)
Superior branch of the oculomotor nerve (CN3)
Inferior branch of the oculomotor nerve (CN3)
Abducens nerve (CN6)
What is meant by the lacrimal apparatus?
Lacrimal glands, ducts and canaliculi
The secretions of the glands lubricate the eye, then they drain through in to the nose via the inferior meatus
What is the venous drainage of the orbit?
Superior and inferior ophthalmic veins, which drain in to the cavernous sinus
What is meant by the danger space?
Communication between facial vein to cavernous sinus via ophthalmic veins
Cavernous sinus thrombosis, meningitis, brain abscess
The facial vein has no valves so blood may pass in the opposite direction and may enter the cavernous sinus
What is the arterial supply to the orbit?
Internal carotid artery gives rise to the central artery to the retina and the ophthalmic artery via the optic canal (lacrimal artery, muscular branches, posterior ciliary arteries)
Also, minor source: intra-orbital artery off the maxillary artery off the external carotid
What is meant by a blow-out fracture?
What are some of the consequences?
Fracture of medial or inferior walls of the orbit
The ethmoid, sphenoid and maxillary sinuses can become full of flood
The contents of the sinuses can spread, causing infection
Muscles in the inferior part of the orbit can become trapped, diplopia
What is meant by enopthalmos?
The eye sits further back than usual (this mp an be due to the impact of an force)
What is meant by the ciliary body? What does it do?
Ciliary muscles and suspensory ligaments It secretes aqueous humour that fills the chambers The contraction of the ciliary body changes the shape of the lens
What are the different chambers of the eye?
Anterior chamber: space between the cornea and iris
Posterior chamber: space between the lens, ciliary body and iris
Vitreous chamber behind the lens, containing vitreous humour
What is meant by the strength of the lens?
Its dioptic strength
defined as the reciprocal of its focal length in m
What is meant by myopic?
the strength of the lens is too strong or the axial length of the eye is too long so that the focus lies in front of the retina
It can be corrected with concave lenses (subtract diopters)
It can correct itself as the lens become weaker with time
What is what is meant by hyperopic?
the lens is too weak or the axial length of the eye is too short so that the focus lies behind the lens
- add on diopters (convex lens)