How and When Does the Upper Lip Close?
Developmental domain · Lesson 5 of 20 · Principles of Biomedical Science (PBS)
Today's goal: Explain that the upper lip closes when the medial nasal, lateral nasal, and maxillary prominences merge and fuse at about human weeks 4 to 6, forming the upper lip, philtrum, and primary palate, and identify this fusion as the step that fails in a cleft lip.
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.
Color key: medial nasal blocks (intermaxillary segment) in blue, maxillary processes in green.
- Right side: fusion line sealed (lip closed), showing the blocks CAN fuse.
- Left side: fusion line open where the green and blue blocks did not meet.
Caption: Mateo's upper lip is open on the left because the maxillary and medial nasal processes did not fuse there at about week 4 to 6. The right side fused normally, which points toward a local, partial failure rather than an inability to form the face.
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: Which blocks must merge and fuse to close the upper lip, and when does this happen?
- 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: On a labeled front-view diagram of the developing upper lip, outline the medial nasal blocks () in one color and the maxillary processes in another. Draw the LEFT line that did not seal for Mateo and the RIGHT line that did, then finish: "Mateo's upper lip is open on the left because the ____ and ____ processes did not fuse there at about week 4 to 6."
- 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 "On a labeled front-view diagram of the developing upper lip, outline the medial nasal blocks (intermaxillary segment) in one color and the maxillary processes in another. Draw the LEFT fusion line that did not seal for Mateo and the RIGHT line that did, then finish: "Mateo's upper lip is open on the left because the ____ and ____ processes did not fuse there at about week 4 to 6."".
- 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.