Visual Pathway and Lesions

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[@champagnepogi]

the order is optic nerve, optic chiasma, optic tract, lateral geniculate body, optic radiations then visual cortex basically

[@Wiimaster20091]

Thanks! I've been looking for a written out version of this for a really long time and I finally found it

[@stevenholmes4339]

@@Wiimaster20091 😂😂😂😂

[@fatihabdjn9877]

بسم الله ما شاء الله لا قوة إلا بالله

[@uwusai]

@@fatihabdjn9877 assingment برضو ههههه ؟

[@BJPdarkhistoryINDIA]

Yes it has been incorrectly labelled as optic tract instead of radiation!

[@abinraji2418]

There is a mistake in this video fibres from temporal hemiretina donot cross, while the fibres from nasal hemiretina cross.

[@blenli]

I was really confused about this concept until I watched your helpful video. Thank you for this!

[@lingsjournal9239]

This is an amazing resource and lovely hand drawn diagrams. Clear explanation too. I remember doing this in my first year of med school and it still sticks with me today!

[@madmedicos3759]

This man just need one page to clear every concepts of the topic😎 you’re incredible 🤩 Thanks a lot sir!❤

[@haneenal-hiari2845]

Thank you, you’ve made it much easier 🤍 Optic nerve -> optic chiasm -> optic tract -> (thalamus) lateral geniculate body -> visual cortex (occipital ) as optic radiation

[@melaniegarrett4156]

THE SIMPLEST VIDEO ON KZbin! I've been confused over and over again. Thank you for teaching it with clarity

[@through_Ameera_]

Yes !!! #Nainann

[@victormuhia750]

armando you are the best artist in explanation videos never listen to foolish critics we respect and appreciate you

[@abdojamal1234]

He's absolutely right, it's all a matter of confusion on your part, and suboptimal explanation on his. Just know the Main Fact and the Main Confusion Point and that will clear up any mist (But before i say them, keep in mind that by saying right or left visual fields i mean the right or the left parts of the SINGLE picture you perceive eventually): 1- The Main Fact: The Right visual field is perceived by the left cortex and vice versa, That's the GOLDEN rule, so keep that in mind as a precondition that has to be fulfilled; so if we want the RT field to be perceived by the left cortex we need A) left temporal fibers and B) Right nasal fibres; and that's simply because the temporal ones don't cross while the nasal ones do. If we were to use the Right temporal fibres (temporal fibres of the Right eye) to perceive the right visual field, that would mean that it would have been perceived by the right cortex, and that would have violated our precondition. Remember that we're talking about the visual field as a whole; as a SINGLE picture. Now let's take the visual field of the right eye setting aside the left one for a second. You need to know that the right eye sees both right and left visual fields (right and left parts of the visual field), so cover the left eye for me for a second and see only with the right one: You'll see the right part of your one-eye visual field using the nasal fibres which will cross and go to your LEFT cortex. the left part of your one-eye (the right one remember) visual field on the contrary, is perceived using the temporal fibres, which will stay on the same side, till it reaches the RIGHT cortex; that means that a man with only one functional eye uses both his right and left cortices!! 2- The Main Confusion Point: Students most often confuse between temporal fibres and temporal part of visual field. and to clear that confusion, just know that the RIGHT part of your visual field has a temporal and a nasal portion (you can think of it as peripheral and central it's only a matter of terminology), so as the left part of that visual field (it has temporal and nasal portions too). The temporal portion of the right visual field is perceived by nasal fibres of the right eye, while the nasal portion of the right visual field is perceived by temporal fibres of the left eye. Read those last couple of sentences again and case closed.

[@UriPhoneCracker]

This was amazing thank you

[@angelwitchpuff5180]

Thank you for explaining this! 🤩

[@tomandband]

thank you suchhh a good explanation

[@hwiatslgeord2887]

Lovely explanatiom

[@pj16904]

Thanks for taking out the time to type out such a great explanation!

[@Suzisart]

Incredible clarity, practicing on my friends this evening, thanks so much .

[@whitepigine7672]

i dont konw what to say, i just hope that such a talent not lost is .... this style of teaching is so high..

[@pajeshjp9087]

Wow now it's perfectly alright. I had doubt in lesions and now it's cleared. This is correct guys. You have to understand the visual field and fibres that catch it concept and you'll get it

[@dedefash96]

Thank you very much for your videos, may I ask what pens you use for your illustrations as they seem really good.

[@medicalvideos7829]

Wonderful video very easy to visualise it when you put it like that. Could have been very helpful for my exam on this subject 2 weeks ago.

[@AndreaJoseph]

This video is perfectly correct in the crossover concept. The axons at the "nasal" retina are responsible for "temporal" vision. That's what is labelled in the video.These cross over at the chiasma. Similarly, the axons at the "temporal" retina are responsible for" nasal" vision.

[@TheAquilaNara]

Yup. He should do the same color for each nasal retina to prevent confusion bcs Im confused too at first haha

[@kshamanthb3285]

Andrea Joseph thanks for the information.. I got little bit confused

[@lralooney6741]

Thanks for posting the info. I was just introduced to this last week. You sound brilliant :)

[@dianal.saldana3017]

thank you, your comment really helped

[@proffezur]

Good video! You explanations on the deficits after the LGN could definitely benefit from further research. The calcarine sulcus separates the parietal and the occipital lobes, and different branches of the visual pathway go to each.. you will have a homonymous quadrantanopia that's either superior or inferior, depending on affected area -- they're not all superior. In factt, what you have actually drawn at "D" would ,more than likely produce a "inferior" quadrantanopia, not a superior one. As it's projecting more towards the parietal.

[@tejuoladeji1590]

i read in my textbook that the fiber from the nasal half of the retina of each side cross to the contralateral while the fibers representing the temporal half REMAINS UNCROSSED

[@MahoganyMilkshake]

Yes, and that's exactly what he has depicted here. You're confusing the retinal fibres with the side of the visual field that they detect.

[@carotidbodies6288]

Yes , same is the case with me and I have confirmed it in three books, nasal one goes to contralateral side and not temporal one

[@anjay_loves]

You're right! I was thinking the same thing then I thought someone in the comment must have pointed it out and I found your comment. Thanks for pointing this mistake out

[@koyesmith8742]

Thanks a lot ....my neurologist teacher just explained this in class recently

[@acashio92]

I was trying to figure this out last week and was so confused. You explained it so clearly, thank you!

[@davonsworld1]

Just won a bet with your video. Priceless! Nice work bro.

[@roselevass3402]

Your drawing are so good!! Thank you! This video really helped me

[@maisara.tijjani4684]

Fantastic job plus nice schema! But i think you should've labelled the nasal and temporal retina somewhere around the eyeballs. Hence clarifying the cross over concept.

[@christianmarkgerardt.tuver4310]

Master Armando, what book do you use as a reference for your videos?

[@aliceh4814]

Can anyone explain why you get macular sparing in a lesion in the geniculocalcarine tract? Thanks

[@yashgandhi1426]

Great video couldn't be that precise and that clear than this 👌 Thanks a lot

[@luke53285]

hey I have a question, several mcat questions cover this topic and state that the right optic track can pick up part of both visual fields but it doesn't mention that the nerve on the left optic track also is connected to the left visual field. is this a mistake on their part? they love asking questions about partial blindness and lesions to different parts of the brain and how they effect vision.

[@lralooney6741]

It seems the beginning with the pathways is review? Does anyone know if there is a video to learn first? Forgive my ignorance

[@Oxcilic]

I'm not even studying this, i'm an arc student but these are so much better than those "educational" Vsauce/smarter everyday type videos.

[@18khaylaraybernadinerondob64]

Hi i have a question. If the fibers that cross overin the optic chiasm are the nasal ones, why is it that the blindness are in the temporal areas?

[@drsunshine6455]

Amazing way of explanation. Your drawing is superb.

[@user-sz5dt9ih7f]

This is just my perspective, so take it for what it's worth. If you ever redo this video, if you draw the two temporal retinal pathways first at the very outset and indicate the nasal fields they cover and then draw the nasal retinal pathways and the temporal fields they cover, it would be a lot easier for students to grasp what's going on IMHO. However, great job as always. Love your videos.

[@Rickenbaker96]

Waaa finally I found a clear, short and precise explanation! Thanks, you removed a big glich in my brain 👌

[@khadijah.b5326]

Optic tract is before lateral geniculate body ,optic radiation is the one after Lgb

[@drdebocherry]

Ok, what happening to cause my far and close vision to switch off every couple of days? Ie. I need bifocals to read computer screen one day and none the next. This corresponds with far vision- I can determine type of bird at birdfeeder one day but not the next.? Thank you.

[@Seca90]

can someone help with an idea? since 2 years i have out of nowhere many maaany seeing conditions (permanent death pixels on static points) and mostly small visual field losses at random (~5 times per minute) been by many eye docs, universitys, scans etc etc etc still nothing...my "structure" is intact they cant find a clue i still have the vision field losses (tiny ones) evey few seconds and othet problems...my whole life turned upside down i really cant even anymore...

[@philipbrowne7620]

Superb video. Well done and thanks!

[@harshitamamodia6618]

thank you very much.... you actually beautifully explained the concept.

[@ukewuihechidinma9715]

Which one is the right and left optic tracts.. is it exchanged? I've searched everywhere. Someone help

[@virnan]

Armando you one gifted individual. Thank you for the excellent videos.

[@mohammadmoradi1800]

The fibres of the nasal half of the retinae decussate in the chiasm and enter the optic tracts before becoming the optic radiation. not the temporal one, are you sure this is correct?

[@Neditarts.]

I have been difficulting in understanding it you explain it so awesomely and simply That I understand it so good thank you so much🌺🌺🌺🙏🙏🙏🙏

[@17ReeM17]

awesome video as usual ! thank you!

[@user-xc6oi9ls5i]

Thank you from iraqi optometrist

[@chrishy566]

Just a silly doubt.. if everything on the left is labelled left anopia etc, why is the optic radiation defect called right homonyms hemianopia? Some one plz explain

[@marianfarfan.fontalvo3539]

Thanks man. AT last. !! I found a really helpful video !

[@davegilmour2250]

Thank you for your awesome work

[@priscilla4175]

Thank you Armando! Still watching in 2020 :)

[@rahuldeb6496]

Hello ,,,is it the real position of optic tract

[@vishwaprashantha7575]

supper .... I Had a big confusion of how the fisual fields of each eye reach the nasal and temporal parts of the retina..... thanks cleared all the douts..... fantastic

[@reache777]

Fantastic video ! Very helpful. Thank you!

[@alejandrobarahona2899]

BRAVO!!! Amazing video!

[@fijianhustler6879]

wait doesnt optic tract come first before lateral geniculate body ????

[@BeulahChukwuma-vn5bx]

Thank you so much sir 🙏 You've made this topic easier 💜

[@ghsh21]

Best explanation Ive seen! Thank you!

[@isaiasyoyo]

Super helpful, thank you for making this!

[@jannatnoor5816]

in guyton and hall, figure 52-1, the nasal sides of both tight and left eye cross at the optic chiasm, which is emtirely different from whats happening here... im confused

[@AminaTanko-h7r]

According to my textbook it say the visual cortex receives information from the temporal part of the same side while the nasal part of the opposite side which means the nasal part is the one crossing not the temporal part

[@5rbashat]

This is amazing! Thank you!

[@chelsea9013]

Regarding lesions at the optic chiasm producing blindness in the temporal regions, is this because the image we are "seeing" is projected onto our retina inverted and backwards?

[@saidnassr9963]

4:07 : If in the temporal part it results in Right Superior Homonimous Quadranopsia but if in the parietal side it results in Right Inferior Homonimous Quadranopsia

[@kushalsingh7180]

Good video i under stood lesions as it was difficult from the book

[@sadiafarooq3817]

Best video ever describing everything in detail.....👍👍👍👍

[@ppi3390]

Can you explain for me why injures point D affect only 1/4 each sight? I dont understand clearly, thanks a lot!

[@3.3m41]

Lesion at D is basically destruction of left inferior geniculocalcarine fibers -also called as Meyer's loop. It carries visual inputs from the inferior nasal retinal quadrant of the right eye and inferior temporal retinal quadrant of the left eye. As a result of lesion at left Meyer's loop, both the eyes lose vision in the right superior quadrants of their respective visual fields. Now you may consider the contrary circumstances for a lesion in the right Meyer's loop.

[@johnkinjimenez2165]

Sellar Mass Lesions affecting optic chiasm can lead to Loss of red perception , Bitemporal hemianopia, Superior or bitemporal field defect, Scotoma and Blindness. How?

[@antonymonir1373]

Fantastic work.

[@fenet8717]

best video- thanku!

[@michoiyaaaa]

Very clear illustrations!

[@MizMeowGi]

I'm kind of confused because in my book the crossover parts are mixed up compared to this video. My book says the left temporal does not crossover, but the left nasal does and the right temporal does not, while the right nasal does. I am very confused.

[@GirItsLiz]

The temporal fibers do not cross over according to my studies as well. From other comments it looks like he labeled them wrong.

[@Be1smaht]

In retinitis pigmentosa what artery is affected

[@ei-sj8dp]

He took my prof's lecture but made 100x better

[@EyYoMrWhite]

youre just amazing. so easy to understand

[@loveride3191]

why its called Right homonymous hemianopia? Though the lesion is in right eye?

[@MW-lt2tq]

What causes binasal hemianopia? Specifically, after anaphylaxis?

[@ukewuihechidinma9715]

Thank you so much for this video

[@786mohammadsohelsarkar]

Very good explanation

[@jiknamdc]

How can a lesion occur on one of the left optic tract and you term it Right Homonymous superior quadrant anopia? You also repeated same on number 3 lesion

[@suhaillone9837]

Actually this video is perfectly alright. Let me explain because the uploader thought we are genius and some of us know and some of us dont know few fundamentals. Basically for example lets take left eye We know there are two type of fibres nasal and temporal. Nasal fibres carry temporal field of vision of same eye and temporal fibres carry nasal visual field of same eye. I hope now u understand the video 😊

[@fredmiller2572]

suhail lone Thanks alot!

[@medhatmamdouh7222]

really thank you man!

[@Arda-Profession]

but thats what he showed when drawing tho

[@lenardsalazar142]

Thank you man! 😊

[@lifestylehub4060]

If temporal fibers are carrying nasal vision then lesions at level of optic chiasma should cause binasal hemianopia because these temporal fibers are actually carrying nasal vision. Isn’t it so ??😑 Someone plz explain this

[@immeow9971]

shouldn't the nasals from both the sides be the one crossing over?

[@AntonisGrr]

terrific vid. thank you

[@NaseersJourney]

Brilliant video! Thank you! 😊

[@iftikharahmad3021]

hi armando you earn the respect with such a artistic way of presentation and make every thing so easy but there is a mistake i would like to mention that optic track is before the LGB and not after that.i hope you will make it clear in coming lecture.

[@rzrzrz3035]

Thank you Dr. armando

[@Fatemah-qg5bt]

Thanks that's help me a lot i have Pathophysiology exam next Wend ,,

[@tithitripathi2242]

Could anyone clarify, whether it's optic nerve from nasal halves criss crossing at optic chiasm or from the temporal halves??? Books like guyton say that it's the Nasal halves but here it's indicated the temporal half. 🙏🙏

[@Hackersuncovered]

I think the video is wrong, my professor also has nasal crossing and temporal staying on the same side

[@preetodedra7589]

Best explanation one can give

[@doyeldasrollno1251]

Sir... In the flowchart/course of visual pathway, doesn't the optic tract come before the lateral geniculate body ? However, at 0:41..plz clarify

[@bijay_07]

Before lateral geniculate body, i.e. optic chaisma -> LGB , it's optic tract , after LGB, it's optic radiation 👍🏻

[@mweembahamalowa5676]

This has really been helpful

[@manuelmirallesmiciukiewicz5880]

Finally understood it!! Thank you!!!

[@twinklepaala5912]

This is great! I understood this very well!

[@srinhalder2282]

Outstanding! in one word.. Absolutely!

[@MahdiandJossie]

Nice Video, but isnt the C lesion meant to be a left homonymous hemianopia due to the fact that the laterality is based on the temporal field of the affected eye. And so the temporal field of the left eye is affected

[@tylerbradley8124]

great video!

[@jgotsch6548]

great visual! thank you :)

[@helloworld3026]

Wow. You explained 1hours worth of lecture in just 2minutes. THANK YOU!!!!

[@zoukinis]

c'était génial merci le sang

[@kishanthakker6813]

Hi I am 29 years old some years back I was hit accidentally football on my right eye it still hurts with the movement and worst part is the coordination of my brain and body or you can say responsiveness to stimuli is not there I even showed to many doctors but I never had any solutions this is very worst can anyone please help me I am clueless

[@shashankjabade7458]

The crossing of fibers in optic chaisma is wrong . Its actually reverse of what is written or mentioned in video . Please correct it .

[@user-wm8pw5zt2d]

A great video! Thank you!

[@claudemulungwa731]

i just got saved from the wrath of physiology...thank you

[@94Torchwood94]

Thanks so much!