Lea Alhilali, MD Profile picture
Feb 16, 2023 17 tweets 6 min read Read on X
1/Your baby’s all grown up! Cerebellum may mean “little cerebrum” but its jobs are anything but little

Do you know cerebellar anatomy beyond vermis & hemispheres?

Here’s a #tweetorial about the functional #anatomy of the cerebellum!
#medtwitter #neurotwitter #neurorad #meded Image
2/Cerebellum means “little cerebrum” or “little brain” bc it looks like a mini brain--a mini me to the cerebrum one might say.

However, it does not play a mini role. In fact, despite being significantly smaller than the cerebrum, it contains as many neurons as the cerebrum
3/When most people think of cerebellar function, they think of balance. And the first thing that comes to mind with cerebellar dysfunction is imbalance & dizziness.

However, the cerebellum is involved in much more, including cognitive functions
4/The cerebellum is divided into anterior & posterior lobes by the primary fissure. Then, along its undersurface is the flocculonodular lobe.

I think this anatomy looks like a dog with his tongue sticking out—the tongue being the flocculonodular lobe
5/Cerebellum has a homunculus. In fact, it has 2!

It has a primary homunculus in along the top of the anterior lobe & a secondary homunculus along the bottom of the posterior lobe—like a reflection of the primary homunculus along the bottom of the cerebellum
6/Cerebellar homunculus looks like 2 gymnasts spread over the top and bottom of the cerebellum.

You have to picture their arms going out laterally, because the homunculus of the cerebellum also spreads out from midline.
7/How to remember which way the gymnasts are facing?

Well, just like the homunculus in the cerebrum, the feet/legs hang over the edge.

So the feet of the cerebellar homunculus are dangling over the edge towards the fourth ventricle
8/Cerebellum is involved in a variety of functions. The functional regions are organized in a gradient.

Most medial regions are for sensory, slightly more lateral for motor, & finally most lateral is for cognitive functions. Bet you didn’t know your little brain was thinking!
9/This distribution actually reflects the evolution of the cerebellum.

As species evolved & the frontal cortex/cognitive functions became more pronounced, the lateral hemispheres of the cerebellum enlarged too—helping to serve these new cognitive functions
10/You can remember this distribution by thinking of the midline as home.

For sensory, you can only sense things close by (touch close by things, see things only in your line of sight).

Thus, sensory doesn’t take you far from home—you have to stay close (medial)
11/With motor functions (ie, walking, running), you can get a little bit away from home. You can run away—but you don’t get too far. There is only so far you can run!

So motor functions are slightly removed from midline
12/Finally is cognitive. With your mind, you can transport yourself anywhere—you can dream of places very far away from home.

So cognitive functions are the farthest removed from home—they are the most lateral
13/This gradient of sensorimotor function being more medial & cognitive functions being more lateral persists for the deep cerebellar nuclei.

There are three main deep nuclei: dentate, interposed (a combination of 2 small nuclei), & fastigial
14/Fastigial is the most medial. You can remember it’s mainly sensory bc fastigial sounds like fastidious, which means sensitive or picky.

Sensitive/sensory means most medial. Big role of fastigial is the sensory input from the vestibular system
15/Interposed is in between.

When you interpose yourself, you kind of insert yourself or intervene in an argument. You are interposed between the two sides.

That is exactly what the interposed nuclei are for—coordinating opposing muscles on the two sides of a motion
16/Last is the dentate nucleus. Dentate sounds like teeth & the dentate looks like teeth as well, with an irregular, almost jagged edge.

Your teeth are in your head, so the dentate is very involved in cognitive function (head = cognitive)
17/So now you know the functional anatomy of the cerebellum—the homunculus, the functional topology, and organization of the nuclei.

So when it comes to the “little brain,” your knowledge will be anything but little!

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with Lea Alhilali, MD

Lea Alhilali, MD Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @teachplaygrub

Jun 4
1/Having trouble remembering what to look for in vascular dementia on imaging?

Almost everyone w/memory loss has infarcts. Which are important?

The latest @theajnr SCANtastic has what you need to know:

ajnr.org/content/46/5/1…Image
@TheAJNR 2/Vascular cognitive impairment, or its most serious form, vascular dementia, used to be called multi-infarct dementia.

It was thought dementia directly resulted from brain volume loss from infarcts, w/the thought that 50-100cc of infarcted related volume loss caused dementia Image
@TheAJNR 3/But that’s now outdated. We now know vascular dementia results from diverse pathologies that all share a common vascular origin.

It’s possible to lose little volume from infarct & still result in dementia.

So if infarcts are common—which contribute to vascular dementia? Image
Read 20 tweets
Jun 2
1/Having trouble remembering how to differentiate dementias on imaging?

Is looking at dementia PET scans one of your PET peeves?

Here’s a thread to show you how to remember the imaging findings in dementia & never forget! Image
2/The most common functional imaging used in dementia is FDG PET. And the most common dementia is Alzheimer’s disease (AD).

On PET, AD demonstrates a typical Nike swoosh pattern—with decreased metabolism in the parietal & temporal regions Image
3/The swoosh rapidly tapers anteriorly—& so does hypometabolism in AD in the temporal lobe. It usually spares the anterior temporal poles.

So in AD look for a rapidly tapering Nike swoosh, w/hypometabolism in the parietal/temporal regions—sparing the anterior temporal pole Image
Read 16 tweets
May 27
1/Feel perplexed by the lumbosacral plexus??

This plexus doesn’t have to be so complex-us

Here’s what you need to know from this month’s @Radiographics!



@cookyscan1 @RadG_editor doi.org/10.1148/rg.240…Image
@RadioGraphics @cookyscan1 @RadG_Editor 2/The lumbosacral plexus is like a love story

The lumbar & sacral plexuses met & fell in love

They loved each other so much they came together to create the nerves to the lower extremities! Image
@RadioGraphics @cookyscan1 @RadG_Editor 3/Lumbosacral plexus is essentially formed by the nerves from L1-S4 (with some other small contributions)

Remember this bc the plexus is to the lower extremitieis and L & 1 look legs and S & 4 look like feet! Image
Read 12 tweets
May 6
1/Have disagreements between radiologists on the degree of cervical canal stenosis become a pain in the neck?

Worried about sticking your neck out & calling severe cervical stenosis?

This month’s @theAJNR SCANtastic has the latest about Cspine MRI!

ajnr.org/content/46/4/7…Image
@TheAJNR 2/In the lumbar spine, it is all about the degree of canal narrowing & room for nerve roots.

In the cervical spine, we have another factor to think about—the cord.

Cord integrity is key. No matter the degree of stenosis, if the cord isn’t happy, the patient won’t be either Image
@TheAJNR 3/Cord flattening, even w/o canal stenosis, can cause myelopathy.

No one is quite sure why.

Some say it’s b/c mass effect on static imaging may be much worse dynamically, some say repetitive microtrauma, & some say micro-ischemia from compression of perforators Image
Read 16 tweets
May 2
1/Do radiologists sound like they are speaking a different language when they talk about MRI?

T1 shortening what? T2 prolongation who?

Here’s a translation w/an introductory thread to MRI. Image
2/Let’s start w/T1—it is #1 after all! T1 is for anatomy

Since it’s anatomic, brain structures will reflect the same color as real life

So gray matter is gray on T1 & white matter is white on T1

So if you see an image where gray is gray & white is white—you know it’s a T1 Image
3/T1 is also for contrast

Contrast material helps us to see masses

Contrast can’t get into normal brain & spine bc of the blood brain barrier—but masses don’t have a blood brain barrier, so when you give contrast, masses will take it up & light up, making them easier to see. Image
Read 20 tweets
Apr 28
1/Asking “How old are you?” can be dicey—both in real life & on MRI! Do you know how to tell the age of blood on MRI?

Here’s a thread on how to date blood on MRI so that the next time you see a hemorrhage, your guess on when it happened will always be in the right vein! Image
2/If you ask someone how to date blood on MRI, they’ll spit out a crazy mnemonic about babies that tells you what signal blood should be on T1 & T2 imaging by age.

But mnemonics are crutch—they help you memorize, but not understand. If you understand, you don’t need to memorizeImage
3/If you look at the mnemonic, you will notice one thing—the T1 signal is all you need to tell if blood is acute, subacute or chronic.

T2 signal will tell if it is early or late in each of those time periods—but that type of detail isn’t needed in real life

So let’s look at T1Image
Read 20 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Don't want to be a Premium member but still want to support us?

Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us!

:(