Pupils Flashcards
what are the 4 fundamental rules of the pupils?
- The normal pupils are equal members of a team
- The pupil control system is so important it has two “managers”
- The normal pupils are subject to a near triad or synkinesis
- The pupils reflect the body in which they live
Both pupils will respond equally if a light stimulus is moved from one eye to another
True or False
True
Both pupils constrict and dilates together. What happens when constrict? dilate?
constrict= get smaller (allows to focus) dilate= get bigger (allows more light in)
Pupils are equal in size. There is about a 0.5mm difference.
True or False
True
what is anisocoria? how much of the population has this?
two different size pupils. 20% of the population has this.
With anisocoria the lids are in normal position. Anisocoria remains the same in any level of illumination.
True or False
True
what are the two pupil managers?
parasympathetic and sympathetic
Rest and Digest
Target is the iris sphincter (responsible for closing the pupil)
Responsible for closing (miosis/pupil constriction)
Pupillary light reflex
Am I parasympathetic or sympathetic?
parasympathetic
what is the neurotransmitter that controls the parasympathetic system?
acetylcholine
name the two types of pupillary light pathways?
afferent= toward the brain efferent= towards the eye
Light illuminates the retina and
Signals are carried by the nerve fibers to brain
am I afferent or efferent?
afferent
The pupil fibers leave the optic tract and enter the brachium of the superior colliculus
To the pretectal nucleus in the midbrain
what pathway is this associated with? afferent or efferent?
afferent
where do the about half the fibers cross? name the fibers that cross.
they cross at the optic chiasm. the nasal fibers are the ones that cross.
From the pretectal nucleus, information is sent to the Edinger-Westphal nuclei on both sides
who am I? afferent or efferent?
efferent
where do fibers synapse in the efferent pathway? where is the end destination? what does it cause the eye to do?
Fibers synapse at the ciliary ganglion
End destination is the iris sphincter
Both pupils constrict!
The pathway back to the eye is via what CN?
CN 3
Fight or Flight Responsible for opening (mydriasis/dilation) Active in a an alert person Target is the iris dilator Two neurotransmitters: Preganglionic is acetylcholine Post ganglionic is nor-epinephrine Am I parasympathetic or sympathetic?
sympathetic
what are the neurotransmitters that control preganglionic and post ganglionic in sympathetic system?
preganglionic= acetylcholine
post ganglionic= norepinephrine
what does the hypothalamus control?
Sympathetic impulses
Via brain stem and cervical cord
In a 3 Neuron Arc First order neuron Second order neuron Third order neuron This is part of the sympathetic pathway. Yes or No
Yes
For the sympathetic pathway:
End of the first pathway ends at C8 T1. (the transmitter that works here is acetylcholine)
Superior ganglion up to the forehead.
True or False
True
sweating is controlled by which neurons in the 3 neuron arc?
1st and 2nd neurons
the 3 neuron arc is mediated by what?
hypothalamus.
Transmitter for 3rd order neuron is norepinephrine (naso-ciliary nerve to pupil dialotor, upper ciliary muscle and lower ciliary muscle).
Reverse ptosis.
True or False
True
what is mydriasis?
“blown pupil” dilation of pupil even in bright light it remains large.
what does hippus mean?
parasympathetic and sympathetic working in unequal equilibrium. sphincter and dilator not working together equally.
what does hippus result in?
results in different types of movement:
1) vermiform movement
2) rhythmic movement
3) normal
Three concurrent events: Not a true synkinesis 1) Accommodation Hyperopes accommodating at distance 2) Convergence 3) Miosis Follows the Para-Sympathetic Pathway To iris sphincter and ciliary muscles Independent of Illumination Decreased accommodative ability (presbyopia) Most of the fibers go to accommodation Can have accommodation but absent pupil reaction Light-near dissociation what is this?
near traid
pupils reflect the body in which they live. in what individuals will you find smaller pupils?
1) Older pupils are smaller
2) The pupils of Diabetics are smaller
3) The pupils of chronic alcoholics are smaller
4) Pain or ocular inflammation will constrict the pupil
