1/
My fellows complained they hate memorizing classifications, like LeFort. I thought, “There must be a better way—maybe understanding instead of memorizing.”
2/ To understand LeFort, you need to understand facial buttresses.
These are not true anatomic structures but a way of understanding facial structure.
Facial bones support facial structures like a table supports food, with legs (vertical buttresses) and table top (horizontal)
3/ In the face, the two main structures the buttresses are supporting are the orbits and the alveolar ridges of the maxilla and mandible supporting the teeth
4/ The buttresses not only support against gravity, but also against the force of mastication, which sends force from the mandible all the way through the maxilla to the skullbase
5/ The buttresses are the table tops and table legs resisting these forces
6/ Horizontal buttresses—there is a tabletop underlying each of the structures that need support in the face: the orbit, maxillary teeth, mandibular teeth, and mandible
7/
Here is the illustration of the horizontal buttresses and their official anatomic names. However, the names aren’t as important as remembering where they are—and you can do that by remembering that each important structure has a tabletop right below it.
8/ Vertical buttresses—these are the support posts. And they are arranged just how you would arrange them if you were building a house. Two in front, two in back.
9/ Here is the illustration of the vertical buttresses and their official anatomic names. But again, names aren’t important—function is!
10/
Vertical buttresses act as suspension wires for the maxilla, suspending it from the skullbase. They are what keep your face on!
11/
LeFort fx is when your face (maxilla) gets take off! To take it off, we have to cut the suspension wires--all three (posterior, medial, and lateral). The posterior buttress (pterygoid plate) is always cut. That is why pterygoid fx's are the signature of LeFort injuries
12/
Where we cut the other two buttresses determines which LeFort fx we get.
And now, you can just think of cutting the suspension wire to the maxilla, and never have to memorize the LeFort classification again!
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1/I always say you can tell a bad read on a spine MR if it doesn’t talk about lateral recesses.
What will I think when I see your read? Do you rate lateral recess stenosis?
Here’s a thread on lateral recess anatomy & a grading system for lateral recess stenosis
2/First anatomy.
Thecal sac is like a highway, carrying the nerve roots down the lumbar spine.
Lateral recess is part of the lateral lumbar canal, which is essentially the exit for spinal nerve roots to get off the thecal sac highway & head out into the rest of the body
3/Exits have 3 main parts.
First is the deceleration lane, where the car slows down as it starts the process of exiting.
Then there is the off ramp itself, and this leads into the service road which takes the car to the roads that it needs to get to its destination
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.