2/Temporal lobe can be divided centrally & peripherally. Centrally is the hippocampus. It’s a very old part of the brain & is relatively well preserved going all the way back to rats. Its main function is memory—getting both rats & us through mazes—including the maze of life
3/Peripherally is the neocortex. Although rats also have neocortex, theirs is much different structurally than humans.
So I like to think of neocortex as providing the newer (neo) functions of the temporal lobes seen in humans: speech, language, visual processing/social cues
4/So let’s start w/the oldest part of the temporal lobe, the hippocampus, and we will move clockwise from there.
5/Next to the hippocampus is the parahippocampal gyrus. I remember this b/c the hippocampus is the oldest part of the temporal lobe & older folks love to go in pairs. So this is the PAIR-ahippocampal gyrus—it pairs w/the old hippocampus
6/Next to the parahippocampal gyrus is the fusiform gyrus. I remember this b/c this gyrus bridges (some might say FUSES) the older, allocortex part of the temporal lobe (hippocampus/parahippocampal) w/the newer, neocortical structures. Fusiform gyrus is the neocortical bridge
7/Fusiform gyrus bridges the older temporal lobe w/the new lateral temporal neocortex.
I think the lateral neocortex looks like a parfait—w/the superior, middle, & inferior temporal gyri layered on top of the fusiform gyrus. Heschl’s transverse gyrus forms the strawberry on top
8/You can remember that the fusiform gyrus is at the bottom of this parfait b/c fusiform means elongated—and the stem of a parfait glass is elongated—almost fusiform!
9/You can remember that Heschl’s gyrus is the fruit on top b/c Heschl sounds like Bushel, and fruit to put on top comes in Bushels!
10/You can also see this parfait in the coronal plane, although it is a little tilted!
11/Last temporal lobe structure is the temporal stem. It is the white matter connecting the gyri of the temporal lobe to the rest of the brain. I remember this b/c I think the temporal lobe looks like an upside-down cauliflower—& the STEM of that cauliflower is the temporal STEM
12/So now you can remember the anatomy of the temporal lobe:
An old couple
A bridge fusing them to the next generation
A delicious parfait
All connected by a cauliflower stem.
I hope this new anatomy knowledge will be anything but temporary!
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3/At its most basic, you can think of the PPF as a room with 4 doors opening to each of these regions: one posteriorly to the skullbase, one medially to the nasal cavity, one laterally to the infratemporal fossa, and one anteriorly to the orbit
1/My hardest thread yet! Are you up for the challenge?
How stroke perfusion imaging works!
Ever wonder why it’s Tmax & not Tmin?
Do you not question & let RAPID read the perfusion for you? Not anymore!
2/Perfusion imaging is based on one principle: When you inject CT or MR intravenous contrast, the contrast flows w/blood & so contrast can be a surrogate marker for blood.
This is key, b/c we can track contrast—it changes CT density or MR signal so we can see where it goes.
3/So if we can track how contrast gets to the tissue (by changes in CT density or MR signal), then we can approximate how BLOOD is getting to the tissue.
And how much blood is getting to the tissue is what perfusion imaging is all about.
1/”That’s a ninja turtle looking at me!” I exclaimed. My fellow rolled his eyes at me, “Why do I feel I’m going to see this a thread on this soon…”
He was right! A thread about one of my favorite imaging findings & pathology behind it
2/Now the ninja turtle isn’t an actual sign—yet!
But I am hoping to make it go viral as one. To understand what this ninja turtle is, you have to know the anatomy.
I have always thought the medulla looks like a 3 leaf clover in this region.
The most medial bump of the clover is the medullary pyramid (motor fibers).
Next to it is the inferior olivary nucleus (ION), & finally, the last largest leaf is the inferior cerebellar peduncle.
Now you can see that the ninja turtle eyes correspond to the ION.
3/But why are IONs large & bright in our ninja turtle?
This is hypertrophic olivary degeneration.
It is how ION degenerates when input to it is disrupted. Input to ION comes from a circuit called the triangle of Guillain & Mollaret—which sounds like a fine French wine label!