Reflexes 2 - Pupillary Light Reflex

www.handwrittenturorials.com - This tutorial is the second in a series of tutorials on the reflexes of the brainstem. This video covers the function and circuitry of the Pupillary Light Reflex. For more entirely FREE tutorials and the accompanying PDFs visit www.handwrittentutorials.com

[@Blakkeh]

Great tutorial! Worth mentioning, the ganglion cells responsible for the pupillary light reflex are in fact instrinsically photosensitive (melanopsin ganglion cells) and do not require input from the rods and cones. A minor point, but just putting it here for people reading the comments.

[@med8615]

thx so much

[@emilypondaven4551]

Thx 😊

[@xsampsakx]

The quality of these just doesn't get old. Clear and simple. 5/5.

[@arthurlandissavingu6886]

The pupillary reflex demystified. Thank you so much!

[@harpinmartin]

@patilsaurabhr You are quite right. My error. We are indeed looking from below upward, but that doesn't change the physiology as the system exists bilaterally.

[@imagination7710]

Agreed his labelling is not a superior veiw

[@TimmysMummy]

I love your videos - thank you sincerely . Charlie in Madrid Spain.

[@Rictoo]

Great video! One thing though: according to two of my textbooks, the bilateral nature of this reflex is due to 1) projection to bilateral pretectal nuclei and 2) communication between the pretectal nuclei via the posterior commisure, and not due to projection to bilateral Edinger-Westphal nuclei.

[@pentopage7572]

Such a good video thanks for making these!

[@drreality1]

Such a great tutorial, many thanks

[@MsDonkeychum]

Your videos are so helpful! Thanks :)

[@healrisewalk]

Wish I would have had this in school. Great tutorial.

[@haneenalteneiji2919]

Thank you!! you are a lifesaver !!!

[@lvolunteerinhospital]

Yes, I agree with you, thinking about the light signal carried by part of CNII optic nerve will go cross the optic chiasm to the other side. So that means shining in one eye will get bilateral pretectal nuclei activated.

[@awilliamspulford]

Great video, the only thing that could have helped me more is having location of lesions and outcome of reflex. I get confused about how the pupils will react with lesion of CN II vs. CN III.

[@Cyrus-po4pr]

Thank you... you are awesome!

[@hatempost]

Thank you for the great video ....Just for the pupil it is constriction .for the muscle it is contraction ..

[@tnagan]

Great tutorial! Thanks very much :)

[@aneikroy9107]

Thanks man...Good concepts...

[@CyReNiUsX]

Just a quick question. Wouldn't the optic nerve cross at the optic chiasm to the contralateral side? But yeah, thanks for the helpful videos.

[@syaza1238]

Thank you so much!!

[@armabaroky9215]

thank u for this very helpfull video

[@LearnForever8]

Wow, this is amazing. Very easy to follow.

[@alinstoi]

great video. thanks for sharing. please correct the first link in the description it contains an 'r' instead of an 't'.

[@chips3078]

Couldn't make it more simple. Thank you!

[@gnc2001]

GOOD JOB!!!!

[@aenychaudhari]

thanks easy & catchy

[@yosun_job]

Thank you...

[@kevinakyuz6762]

kudos to you

[@medic9351]

tank you very much!!

[@mohammedamir4383]

Gerat viedo ,,help me alot ,,,thnx

[@miRoshevich]

As we know , pretectal nucleus is at optic TRACT, not optic Nerve. It is behind Optic chiasm. So, why there isn'y included crossing of the nasal portions of optic nerve?

[@paulinec9627]

that is the visual pathway. this is the pupillary light reflex pathway. hope it helps

[@DanneJaha]

This pathway still has a crossing over at Chiasma Opticus for the Nasal part of the Visual field. The temporal will stay on same side. This means that light reflex will be triggered from both sides and also to both sides in the Pretectal Nucleus.

[@mohamedmagdy621]

waooooooooooooooooooh .nice work

[@Kimono0001]

Good , thx

[@shontaethompson9773]

great

[@ziiamkyz]

Maybe he was referring to the CN III from the temporal side and not the nasal side of the retina.

[@Zion-1610]

Amazing zing

[@rayamoooooo685]

*2020 awesomeness*

[@draloksharma3741]

where is optic chiasma and lgb?

[@zainabfadhil5755]

👍👍

[@charpieedruggiee]

constriction of pupils...

[@SaurabhPatil1]

No! We are not looking top-to-down. We are looking from inferior side to superior. (Like watching at someone's chin from below)

[@MrCupka]

the smooth muscles of the eye are not innervated by CN III
they are innervated by n.ciliaris brevis (which has sympathetic and parasympathetic) which is a branch of n,nasociliaris of ophtalmic branch of CN V.
and although uncalled for if you are drawing a midline then i guess your left and right are wrong.
please correct the video.

[@arnoldtang3570]

No the pupillary light reflex is motor because of the constriction of the ciliary muscles. V1 of CN V is purely sensory.

[@davidsantos1154]

I agree that the diagram is wrong if we are looking from the superior (top) aspect. The left would be the bottom eyeball and the right would be the top eyeball. From what I've learned, CN III (purely muscular) is in charge of pupillary constriction or contraction if referring to the iris sphincter muscle, and CN II (purely sensory) is in charge of pupillary light reflex. The term pupil refers to the hole, therefore it cannot contract, only muscles contract. The pupil can constrict to be anatomically correct. Good tutorial, please make corrections.

[@davidsantos1154]

V1 of CN V is in charge of pupillary dilation, not constriction. Pupillary dilation has no invovlement with the pupillary light reflex.

[@davidsantos1154]

*****
In what way? Please defend your statement, unless you're an idiot.

[@Wesley132100]

David Santos I think the guy above who you thought was calling you a moron tagged you to agree with your statement, and called the original commenter (Rishikesh) a moron..

[@jessicahergert8513]

THIS IS WRONG

[@pokoirlyase5931]

Euh .. No .. Everythin'his said is correct

[@ghassanauf8103]

poor video , sorry

[@medic9351]

tank you very much!!