How and When Does the Upper Lip Close?
Take the reading one piece at a time. For each piece: read it once, underline the sentence that says what happens, then look up any word in the list. Tap a word to see its definition.
Piece 1 of 2
Read the fusion rows in order. At the end of week 4 nasal pits split the frontonasal prominence into medial and lateral nasal processes. During weeks 4 to 6 the medial nasal processes merge into the intermaxillary segment, the maxillary process fuses with the medial nasal block on each side, and the upper lip closes. In weeks 5 to 6 the primary palate forms from the intermaxillary segment, the front triangle of palate anterior to the incisive foramen. Putting it together, the lip closes at about human weeks 4 to 6 when these blocks come together.
Piece 2 of 2
Told as failure: if the maxillary and medial nasal processes do not fuse, the upper lip does not close, producing a cleft lip that can be on one side or both and can extend up into the nostril and back through the gum. Because the same fusion also seeds the primary palate, the failure often extends backward, which is why cleft lip with cleft palate is one developmental group. Mateo's chart says complete unilateral (left) cleft lip and palate with no other birth defects found, so the left-side fusion did not complete.
Reading the Research
- Skim the title and abstract first to get the gist.
- Circle the one sentence that states the main claim.
- Box the evidence the authors give for that claim.
- Mark one sentence that confuses you, and move on.
Now put it together: In one or two sentences, say what this whole reading is telling you about Mateo. Then go back to the lesson and fill in the guided notes.