Special Senses Flashcards
Eyebrows
Functions
Muscles controlling
Shade/protection from perspiration
Corrugator supercilii: medial movement
Orbicularis oculi: depresses eyebrow
Eyelids (palpebrae)
Space between eyelids:
Connection points for eyelids
Part that produces white secretions
Muscles for opening/closing
Palpebral fissure
Medial/lateral comissures
Lacrimal caruncle
Orbicularis oculi, levator palpebrae superioris
Does conjunctiva line cornea? Why
No, would distort image
Tear pathway
Produced in lacrimal gland (upper/lateral eyelid)
Wash across lower eyelid (lateral -> medial)
Collect at lacrimal Punctum
Enter lacrimal Canaliculi
Lacrimal sac
Drain into nasolacrimal duct
lacrimal caruncle not involved
Eye muscles
4 rectus (functions)
2 obliques (functions)
Sup/Inf/Lat/Med rectus (pull eye in that direction)
Sup/Inf oblique: (pull in opposite direction)
Eyeball tunics (functions)
Sclera
Choroid
Retina
Scelra: white of eyes (outermost layer)
Choroid: provides nutrients for sclera/retina (dark brown staining)
Retina: seeing light
Functions:
Ciliary muscle
Sphincter papillae (+NS association)
Dilator papillae (+NS association)
Controls shape of lense
Closes pupil (parasympathetic)
Opens pupil (sympathetic) see more of scary situation
Sensory tunic (retina)
Outer pigmented layer: function
Transparent inner neural layer: function
Prevent light scattering/remove dead cells
Contains photoreceptors
Age-related macular degeneration (AMD)
Dry vs wet AMD
Dry AMD:degradation of pigmented layer (loss of macula)
Wet AMD: choroid blood vessels grow abnormally (loss of macula)
Retinopathy
What happens
Is clot removed?
Weak blood vessels leak, cause clot in vitreous humour (blindness)
Clot not removed (fluid is not renewable)
Posterior segment
Where
Which fluid
What type of pressure provided
behind the lens
vitreous humour
Intraocular pressure (holds retina against choroid)
Anterior segment (two chambers)
Where
Which fluid (function)
Fluid pathway (produce, pass, drainage)
Pressure
Anterior/Posterior chambers
Lens-Cornea
Aqueous humour (nourishes/removes waste)
Produced by ciliary processes, posterior -> anterior chambers -> drains through scelral venous sinus (Schlemm)
Intraoculuar pressure
Glaucoma
Bad drainage of what fluid
Causes what
Common in who
Aqueous humour, pressure builds up causing damage to optic nerve
Common cause of blindness in old people
Lens
Shape
Flexible?
Vascular? (why)
How does aging affect?
Biconvex
Flexible +transparent
Avascular (not to hinder light passage)
Lens becomes more dense (loses elasticity-> vision loss)
Cataracts:
Improper clumping of what protein
Improper clumping of crystalline protein
Light can’t pass through lens
Which wavelengths can we see? (nm)
400-700 nm
What do each lens do?
Concave:
Convex
How is the image flipped in the brain
Concave: diverges light
Convex: converges light
Brain flips image across x and y axis (to make it normal)
Pathway of light (start from cornea)
Cornea
Aqueous humour
Lens
Vitreous humour
Retina
Photoreceptors
Light pathway to photoreceptors, then to brain
Ganglion cells (no rxn), Bipolar cells (no rxn), Rods/Cones
Rods/cones, bipolar cells, ganglion cells, optic nerve, brain
Focusing for distant vision (>6m)
Rays come in …
How much change is needed by ciliary muscles
Which ANS controls?
Parallel
Minimal change
Sympathetic system
Focusing for close vision (<6m)
What does ciliary muscle do to lens:
What does spincter papille muscle do
Rotation of the eyeball: medial or lateral?
Which ANS controls?
Rays come in divergent
Ciliary muscle: contracts, lense BULGES
Sphincter papillae constricts pupil (to reduce divergent rays)
Eyeballs rotate medially (convergence)
Parasympathetic
Vision correction
Emmetropic?
Myopia: what’s wrong, what’s needed
Hyperopia: what’s wrong, what’s needed
Good focusing ability
Myopia: near sighted, need concave lens (open up/diverge light)
Hyperopia: far sighted, need convex lens (converge light)
Fovea:
Within which structure:
Why is it high detail focus?
Within retina
High concentration of cones, no bipolar/ganglia cells in the way of light here
Rods/cones
Two main segments: outer/inner
Position (post/ant)
contents
Outer segment: posterior, contains rhodopsin discs
Inner segment: anterior, contains organelles/mitochondria for energy