Pupillary control - Horner syndrome Flashcards
miosis mechanism - 1st neuron
Edinger-Westphal nucleous to ciliary ganglion via CN III
miosis mechanism - 2st neuron
short ciliary nerves to pupillary sphincter muscles
pupillary sphincter muscles - receptors
M3
A consensual reflex is
any reflex observed on one side of the body when the other side has been stimulated
Pupillary light reflex - mechanim
Light in EITHER retina sends signals via CN II (and chiasm and tract) to pretectal nuclei in midbrain that activates bilateral Edinger-Westphal nucleous –> Pupils contract bilaterally (consensual reflex)
Pupillary light reflex - direction of the signal from retina to Edinger-Westphal nucleous
light –> retina –> optic nerve optic chiasm –> optic tract –> pretectal nuclei (midbrain) –> bilateral Edinger-Westphal nucleous
CN that participate in Pupillary light reflex
optic nerve (CN II) Oculomotor nerve (CN III)
miosis - number of neurons
2
mydriasis - number of neurons
3
mydriasis - 1st neuron (beginning and end)
hypothalamus to ciliospinal center of Budge (C8-T2)
Synapse in the lateral horn
mydriasis - 2nd neuron - direction
exit T1 - travels along cervical sympathetic chain near lung apex, sublavian vessels - superior cervical ganglion
mydriasis - 3rd neuron - direction
superior cervical ganglion - plexus along internal carotid through cavernous sinus - enters orbit as LONG CILIARY NERVE - sypathetic fibers also innervate smooth muscle of eyelids (minor retractors) and sweat glands of forehead and face
mydriasis - 3rd neuron - innervate
- pupillary dilator muscle
- smooth muscle of eyelids (minor retractors)
- sweat glands of forehead and face
mydriasis - 3rd neuron is going through
cavernous sinus
long vs short ciliary nerve - according to eye control
long: 3rd neuron of Mydriasis
short: 2nd neuron of Miosis