Getting Above the Tongue: Palatal Shelf Elevation
Developmental domain · Lesson 7 of 20 · Principles of Biomedical Science (PBS)
Today's goal: Explain how the vertical palatal shelves rotate to a horizontal position above the tongue, and identify one mechanical and one tissue cause of failed elevation.
What a finished product looks like
This is a model of the work you should turn in. Use it to check your own: match the structure and the level of detail, do not copy it. Your wording should be your own.
Act 2: Elevation. At about week 8 each vertical shelf rotates roughly 90 degrees to horizontal above the tongue. This needs internal remodeling (hyaluronan swelling the shelf) AND external room (the tongue descends, the head widens).
- Tissue cause of failure: the shelf cannot remodel its matrix/mesenchyme to flip up.
- Mechanical cause of failure: a small jaw holds the tongue up and blocks the path (Pierre Robin sequence, about 85 percent cleft palate).
Pierre Robin call for Mateo: does NOT fit. His jaw is normal-sized and his exam shows no other anomalies, so the mechanical small-jaw route is ruled out. That points away from a mechanical cause and keeps the search on other steps.
How this was built, step by step
The finished product above did not appear all at once. Here is the path from the question to the turned-in work, so you can follow the same steps.
- 1Start from today's question: How do two downward-pointing shelves move to a position above the tongue, and what can stop them?
- 2Work the Model and the Explore questions to reason it out before writing anything.
- 3Pull the specific evidence the product needs from the reading and any database you used.
- 4Write it up in the required format: Add the "Act 2: Elevation" entry to Mateo's developmental chart: describe the position change, name one cause and one mechanical cause of failed elevation, then make a call about the small-jaw (Pierre Robin) route for Mateo given his normal jaw and otherwise normal exam, and note what your decision rules out.
- 5Check it against the rubric, then submit.
| Criterion | Proficient | Developing | Beginning |
|---|---|---|---|
| Complete | Every required part of the artifact is present and filled in. | Most parts are present, but one is missing or left blank. | Several parts are missing. |
| Accurate | The science and data are correct and match the evidence. | Mostly correct, with a small factual slip. | Key science or data is wrong. |
| Scientific reasoning (CER) | States a claim, backs it with specific evidence, and explains the reasoning. | Has a claim and evidence, but the reasoning is thin or missing. | Gives an answer with no evidence or reasoning. |
| Professional communication | Clear, organized, and labeled the way a clinician or scientist would write it. | Readable but disorganized or missing labels. | Hard to follow. |
| Submitted | Turned in the right way (Schoology for routine work) and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
- CompleteProficient: Nothing is left blank: the model fills every part of "Add the "Act 2: Elevation" entry to Mateo's developmental chart: describe the position change, name one tissue cause and one mechanical cause of failed elevation, then make a call about the small-jaw (Pierre Robin) route for Mateo given his normal jaw and otherwise normal exam, and note what your decision rules out.".
- AccurateProficient: Every number and claim matches the case evidence.
- Scientific reasoning (CER)Proficient: It names a claim, cites the specific evidence, and explains the reasoning, not just the answer.
- Professional communicationProficient: It is organized and labeled like a real chart note.
- SubmittedProficient: It would be turned in on Schoology and confirmed.
WebXam problem for today's skill
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.