Anatomy 2 - High yield facts Flashcards
Name of gland on eyelid that produces the oily substance that prevents evaporation of the eye’s tear film?
Meibomian glands (produce meibum)
What muscles control eye opening?
Muller’s muscle and levator palpebrae superioris
What is the nerve supply to levator palpebrae superioris?
CN III
What is the nerve supply to Muller’s muscle?
Sympathetic control
What muscle closes the eye?
Orbicularis oculi
Nerve supply to orbicularis oculi?
CN VII
Why can Horners syndrome cause ptosis?
The muller muscle (sympathetic supply) assists the levator in elevating the top eyelid -> sympathetic innervation can be compromised in Horners syndrome
What muscle does the orbital septum lie just posterior to?
Obicularis oculi muscle
What is orbital cellulitis?
Inflammation psoterior to the orbital septum (sight threatening)
Name of cellulitis just anterior to the orbital septum called?
Preseptal cellulitis
What are the 2 parts of the obicularis oculi?
What is each part involved in?
Orbital part (closing eye tightly) Palpebral part (normal blinking)
Approximate pH of the tear film?
7.6
What nerve is required for reflex tear production?
Trigeminal nerve
3 phases of the tear film?
Lipid phase
Aqueous phase
Mucus phase
Afferent part of tear film production?
5th nerve -> tells the brain that the eye needs tears
Efferent part of tear film production?
7th nerve parasympathetic fibres
What is the name of the conjunctiva that lines the inner surface of the eyelids?
Palpebral conjunctiva
Name of the conjunctiva that lines the eyeball?
Bulbar conjunctiva
Is the palpebral or bulbar conjunctiva more vascular?
Palpebral
What does the conjunctiva contain that secretes part of the tear film?
Goblet cells
5 layers of the cornea from outside in?
Epithelium Bowman's membrane Stroma Descemet's membrane Endothelium
What part of the cornea is thickest?
Peripheral part
What type of fires does the stroma of the cornea contain?
Regularly spaced collagen fibres
What part of the cornea maintains it’s transparency and how does it do this?
Stroma
Pumps fluid out of the storma
What is the name of the outer layer of the lens?
Capsule
What attaches the lens to the ciliary body?
Zonules
Does a decrease in tension of the zonular fibres cause you to focus near or far?
Near
Do the lens fibres have good regenerating properties?
No
Name of the outermost part of the lens?
Cortex
Name of the innermost part of the lens?
Nucleus
3 parts of the uvea?
Iris, ciliary body and choroid
Purpose of the uvea in terms of light?
Absorbs reflected light
What 2 parts of the eye does aqueous humour drain into?
Canal of Schlemm
Trabceular meshwork
How does the aqueous fluid allow for optical clarity?
It has a low protein content
Afferent limb of pupillary response?
Retina -> optic nerve -> pre-tectal nucelus
What does the pre-tectal nucleus project fibres to in the pupillary reflex?
Edinger-Westphal nuceli
Efferent limb of pupillary response?
CNIII -> short ciliary nerve
What is the name of the pupillary reflex action which causes the eye that is not having light shone in it to constrict?
Consensual response
What nerve provides the last part of the efferent limb of the sympathetic pupillary response?
Long ciliary nerve
What is the stimulus for the accommodation reflex?
A blurred image on the retina
What are 3 responses of the accommodation reflex?
Convergence
Pupillary constriction
Contraction of the ciliary muscle
What is unique about the trochlear nerve?
It arises from the dorsal aspect of the brainstem and crosses over (lesion of the left trochlear nucleus produces a contralateral muscle palsy)
What fissure does the trochlear nerve pass through to enter the eye?
Superior orbital fissure
How many nuclei does the trigeminal nerve arise from in the midbrain and medulla?
3
What branch of the trigeminal nerve usually supplies the tip of the nose?
Nasociliary branch of CNV1
What does all the rectus muscles arise from?
The common tendinous ring
Why does optic neuritis cause pain on eye movement?
The optic nerve sheath is attached to the common tendinous ring
What rectus is the strongest and thickest?
Medial
What part of the retina are cones found in the highest density?
Over the fovea
What type of epithelium is the retinal pigmented epithelial cells comprised of?
Cuboidal epithelium
What cells of the retina gives rise to the optic nerve?
Ganglion cells
Where in the visual field is the retina located?
15 degrees temporally
What structure supplies the outer layer of the retina (that not supplied by the ophthalmic artery)?
Choroid
What does the superior ophthalmic vein leave the eye via?
Superior orbital fissure
What does the superior ophthalmic vein drain into?
The cavernous sinus
What passes through the supraorbital notch?
The supraorbital nerve and vessels
