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Previous Topic | Next Topic  Sphincter and Dilator of Eye 




 
Kaplan Qbank USMLE



Author4 Posts
  #1

This confuses me on how innervation is made to sphincter pupilla and dilator muscles of eye.

SPHINCTER:
Preganglionic parasymphathetic: oculomotor n
Postganglionic parasymphathetic: short ciliary n

DILATOR:
Preganglionic SYMPHATHETIC: superior cervical ganglion
Postganglionic SYPMPHATHETIC: short ciliary n

Are these right for Sphincter and Dilator muscles?


  #2

I dont quite understand what you are writing here.

for preganglionic, that would be preganglionic NERVE right? hence u mentioned CNIII. superior cervical ganglion is not a nerve

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  #3

What he means is that the preganglionic sympathetic axons synapse with the post ganglionic neurons in the superior cervical ganglion, which then send out their axons as the short ciliary nerve to the dilator muscle.

  #4

And for the sphincter muscle hes used a different method of elaboration, hence the confusion. Hes saying the preganglionic PS neurons are in the CNIII nucleus, whereas the postganglionic PS axons reach the muscle as the short ciliary nerve. Hes completely skipped the ganglion here.







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