Anatomy | Physiology of the Utricle & Saccule [Otolithic Organs]
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- เผยแพร่เมื่อ 8 ก.พ. 2025
- ⚡ Welcome to Catalyst University! I am Kevin Tokoph, PT, DPT.
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I cannot thank you enough, I’ve been struggling to understand this, but you made it crystal clear & that’s cuz you’re tremendously knowledgeable.
Absolutely incredible!! Thank you so much for the extremely clear and precise explanations
this video saved my life and my medical future
Thank you so much! this topic couldn’t have been explained better.
Thank you for the kind words.
So helpful! Repetitions are great. Thanks a lot for making these videos available to public.
Great video! I just want to point something out about the illustrations involving the crystal structures, as it might lead to some misunderstanding. The line pointing to the crystals at the top should actually say "Otoconia," because those are the calcium carbonate crystals themselves. "Otoliths," on the other hand, are actually referring to a larger structure, which includes the otoconia and the otolithic membrane they are embedded in.
You can think of the otoconia as all of the individual pixels on your screen and the otoliths are the full image, made up of all the pixels working together to form a picture.
This is great! the car examples and variety of images really does a lot!
It sounds like that the head flexion or turn head left cost less energy as both have less frequent depolarization as compared to head extension and turn to right which cost more energy by triggering more depolarization. So, depending on whether one wants to spend or save energy, the corresponding movements can be prioritized.
How beautifully organised lecture it is !!!
I don't normally subscribe but you sir explained everything clear. Subscribed!
Awesome, thank you!
Thank you for the details. Everything is easy to understand.
You deserve all support, I have liked and subscribed the channel..your explanation is organized and on the point, many thanks
Thank you!! One of the best videos, please make one about hearing and spatial senses
Thank you. Currently I do have some videos over hearing. I am planning on making a couple over taste and smell as well.
Ah thankyou so much! You made it so easy! Love and respect from 🇵🇰
Amazingly clear video lesson. Thanks.
Thank you for making this clear! I had a hard time understanding it from my text book.
Great material! Clears things up after a lecture perfectly
Great explanation and waiting for more😍 👌👌👌👌❤️❤️❤️ thank u so much
Thanks you so mush 😊❤️ to post this video and put all this work in it 💝
Such an amazing video, really clear!!
Thanks so much for this info! I'm currently dealing with vertigo and this really helped me understand what's going on ❤️
Thank you, one of the best videos on this subject :)
Really appreciate your videos - so helpful. Thank you.
Subscribed on the spot! Ouuuff such a clear explanation ! So great
Omg😭😭
Thank you so much Sir!!
🙌🙌🙌
Best explanation sir.thank you
The video was extremely helpful and made this topic so much easier to understand!
Thank you! the best video I could find for my questions
Thank you!
Great explanation! 👍Thank you!
Thank you for your help! I was struggling with this and this video made it easy to understad!
Clear and concise explanation. Many Internet sources make it sound as though an otolith is connected to the end of each cilia "like a crystal on the end of a blade of grass." This is a much better depiction. One question: diagram "D" shows the cilia being forced right under acceleration. Should not the otolithic membrane also be bulging right under acceleration as in "B"--since the membrane is what actually manipulates the cilia?
incredible video, thank you
Thank you for giving such a detailed explanation. It was very helpful!
Glad this helped you!
Very informative, thank you for taking the time to make this video. There was however a part of the video with some miss information that I'd like to bring your attention to. When you were talking about deceleration in relationship with head extension, and acceleration in relation to head flexion, you actually have those backwards. Deceleration will give the same feedback as head flexion, and acceleration will do the same as head extension. Otherwise you video was very accurate and well explained.
Thank you for a very helpful video. How is head movement during car acceleration or deceleration, called left and right linear acceleration ? Why is is not called forwards and backwards linear acceleration ?
Because I think the way the utricle is positioned in the head.
I think it‘s just describing the slide. Forward=right on the slide, but in reality it’s anteriorly, if that makes sense
Great video, thanks so much!
Thank you very much! Everything is very clear!
Thank you!
please explain how bending flexing the neck forward is a linear movement? otoliths are sensitive to linear acceleration or deceleration. bending the head seems more angular movement which should be detected by the semicircular canals.
The movement of tilting the head forward will be registered by the semicircular canals as well. Static position of head with neck flexion changes the axis of the otolith so when gravity acts on the otoliths they will register the same was as with linear acceleration. If you're familiar with physics you can think of force of gravity down the "ramp" of the otolith membrane as linear acceleration.
Otoliths:
If you look up (extension), it is a linear motion. If you look down (flexion), it is a linear motion. You could argue that the semicircular canals are partially involved with the movement, but it is a very small amount of involvement when compared to the otoliths.
Semicircular canals:
If you move between the two (extension/flexion) repetitively, you are now moving along an axis (back and forth) which is considered head rotation/motion. This means that the semicircular canals are now more involved.
Thank you.. 🤗 you made it easy
Amazing. Seriously, ❤️❤️😍☺️
Awesome lecture!!!!! Can't thank you enough!!!!!
Thank you!
Thank you!Great video👍🏼
Very helpful , thank you
Finallyyyyyyyyy.... Thank youuuuuuuuuuu!!!!!!
You didn’t explain why bending head to left side increase firing level while to right side decreased
I guess its more about whether it is bending "towards" or "away from" the kinocilium (the tallest cilium), where "towards kinocilium" increases the signal, and "away from kinocilium" inhibits signal firing...I remember this increase/decreased firing action is related to the structure of ion channels on the kinocilium what open and close according to the direction the kinocilium is bent...for more details might need to look that up as well.
(for anyone if I'm wrong please correct me thanks!)
@@gangrenefantasia4936 u r correct
Bestest video!😊👌👌
Great video!
so at head flexion hair cells where bending with the direction of otolith movement just fine. but when it's right of left deceleration the inertia concept just shows up!
Really thank you , it was very very helpful.
Thank you so much 💓 🔆🌹
Thank you!
Excellent
In your example, head extension causes hair cells to shift posteriorly. This results in increased nerve firing. In the case of linear acceleration, hair cells of passenger in car would also shift posteriorly and nerve firing should also increase. Your example shows that nerve firing would decrease which doesn't make sense to me. Please explain. Thanks!
thank you
i enjoy your lecture
If utricle transduces left/right acceleration and saccule transduces up/down acceleration, what transduces front/back acceleration (as in your car driver example)? Or does the utricle transduce all horizontal acceleration including front/back?
Hi, Thank you very much for wonderful lecture,I just have one question, why there is increase firing rate of neurons in head extension movement ?
Amazing, Thank you
In this case, when we go in one direction, the inertia doesnt move the endolymph in the opposite direction like in the case of semicircular canals?
Linear acceleration does not mean linear direction. Linear acceleration implies a constant (linear) increase in velocity over time. You can linearly accelerate around a curve, for example. Great video, thanks.
This was very useful for my premed entrance exam.
So the otoliths and otolithic membrane only shift when the head is tilted?
best video
The diagram "(D) Linear acceleration to the left" is a bit confusing. It it shows only the cilia deflected to the right with no deflection of the membrane or the otoliths. Surely it should show the otoliths and otolithic membrane deflected towards the right as well as the cilia.
Easy understanding with 4 slides
very informative
Sooo is’t that the saccule/utricle tell the brain the head’s position when tilting but the semicircular canals tell the brain the movement of the tilting?
Why macula does not need basal cell to generate new supporting cell and hair cell?
Is this the tonic firing rate ?
Very educational.vertigo x3. Had left and right ears. Still got this prolonged imbalance. Could l be having vertical nodding crystals drifted out of place. Almost sudden shift movent in the mind.....standing or getting up from bed.....
Amazing
I do not understand what you mean by linear acceleration to the left. Please what does that mean ???
Thank you so much! So nicely taught, i am finally able to understand how the vestibule works after so long.
At the beginning of the video I heard that there was a little difference between the utricle and the sacule, which would be explained at the end. Did I miss that little detail, or was that just a ruse to keep us watching?
the difference is the positioning, that one is horizontal and the other vertical (I guess a year to late to answer, but better late than never xD)
Does the rate of firing depend on whether the stereocilia move towards or away from the kinocilium?
yeah it does...if the stereocilia moves towards the kinocilium, the firing rate will increase
Does otoliths dissolve in canal or utricle after dislodge
is the endolymph relevant for utricle and saccule or is that only for semicircular canals and cochlea?
You're the best! unlike my teacher :(
I have a question. I've read that head extension & head flexion are done by the semicircular canals (rotation) instead of the otolithic organs (doing linear acceleration). But here you also talked about head extension & head flexion in the utricle and saccule. So I don't understand, what am I missing?
Hello! Sorry that this is about 4 years later than you'd like.
TLDR:
Semicircular canals --> don't directly detect linear movements, but they contribute to the overall sense of head motion and rotation from fluid movement throughout the canals.
Otoliths --> contribute to the overall sense of the head's position as they sense linear (one direction) movements from gravitational forces within the otolithic organs.
Therefore, head flexion and extension (linear movements) are primarily handled by the otoliths. You could argue that there is a small amount of involvement (fluid movement) from the vertical semicircular canals, but it is only a small percentage compared to the otoliths.
Main explanation:
Imagine the semicircular canals (relative to fluid movement) as gyroscopes in a drone that spins and tilts side to side. When you're nodding up and down, tilting your head to your shoulder, or shaking your head side to side, the fluid movement in the canal bends the semicircular canal hair cells and sends signals to your brain about the heads rotation/motion. It's like seaweed anchored to the bottom of a fish tank. When you move the water in the tank, the seaweed bends and sways with the movement of the water.
Imagine the otoliths (relative to gravitational movement) as sensors in a car that detect when you are speeding up or slowing down. When you tilt your head forward (flexion) or backward (extension), the otoconia (crystals embedded on the otolithic membrane) in the otolithic organs (Utricle and Saccule) bend their hair cells from their weight and send signals to the brain about the head's position. It's like weights hanging on a spring. When you tilt the spring, the weights shift to the new lowest point.
Now, the difference between nodding and head flexion/extension can be a little confusing and might be where the confusion is coming from (it did for me at least). Nodding is a series of repetitively changing positions between flexion and extension. These movements are considered rotational/motion. General head flexion/extension is simply titling your head down to look at your feet or tilting your head up to look at the sky. These movements are considered linear, because the change in head position is moved along a single straight line. In other words, if I just look up (extension) and keep my head looking up, this is positional and handled by the otoliths. As soon as I start switching between extension and flexion (back and forth), I am now moving my head around an axis, which is motion and is handled by the semicircular canals.
Kudos! Well done! This enhances my audiology knowledge greatly.
Hi there! Where did you get your slides?
Why when you accelerate/decelerate do the otoliths not move in the same way they do in flexion/extension?
When the head undergoes linear acceleration, the greater relative mass of the otolithic membrane causes it to lag behind the macula temporarily, which in turn leads to transit displacement of the stereocilia.
I wanna see a picture of saccule otolith
Awesome
Respected Sir, I had have some hearing issues. Anyone attention to me In first time. I can't understand that word in first time spoke. Even When They repeat again that word. Also upper neck Pain with shoulder every day off. What kind of problems. Kindly advise
left out striola? doesn't really explain how you get response in combination of directions
great
7/3 is the SAT-like test(but hard af) in Taiwan and I'm watching this in 7/1......
How about exam? Just checking
Sup my bestfriends . I miss you so 😅
I have Bppv. I hate those otoliths...
No not you.
😂
Thank you!